Home » CEEFAX disks » telesoftware10.adl » 18-11-88/T\MOU00
18-11-88/T\MOU00
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » CEEFAX disks » telesoftware10.adl |
| Filename: | 18-11-88/T\MOU00 |
| Read OK: | ✔ |
| File size: | 43F1 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
Using a mouse with the BBC microcomputer - by - Gordon Horsington
-----------------------------------------------------------------
Module 0. Introduction
----------------------
An AMX compatible mouse can be used with the BBC B, BBC B+ and Master
series computers. This module introduces a block of seven modules which
deal with the design of software which will allow a mouse to be used
without its manufacturers control ROM or any other alternative software. A
mouse can be bought without a control ROM and, if you don't want to use
the art software that these ROMs contain, then buying just the hardware
halves the cost of owning a mouse. I hope to demonstrate that the software
you can easily create yourself can be just as useful as the software that
the manufacturers supply.
The seven modules are in files named T/MOU00 to T/MOU06. The following
topics will be covered in these modules.
Module 0. This module. Introduction and the User Port.
Program: TESTMOU
Module 1. Reading the mouse coordinates.
Program: MOUSE
Module 2. Tube compatible mouse software.
Program: SPMOUSE
Module 3. Polling the mouse buttons.
Programs: EVENT BUTTONS
Module 4. Reading a mouse with the negative INKEY and the keyboard scan.
Programs: NEWKEYS LOADER NEWSCAN
Module 5. Reading a mouse with the BASIC ADVAL command.
Program: ANMOUSE
Module 6. Using Sideways RAM for mouse software.
Programs: SWMOUSE SWRMICE SWTEST
The later modules develop the ideas and techniques described in the
earlier modules and for this reason they need to be worked through from
module 0 to module 6 rather than used as a reference guide. It is
necessary to have either BASIC 2 or BASIC 4 and operating system 1.20 (or
higher) installed in your computer.
The User Port
-------------
There are two 6522 VIAs in the BBC B. VIA-A is used for internal functions
and the joystick fire buttons and is usually called the system VIA. VIA-B
provides the parallel printer interface and the User Port. An AMX
compatible mouse is connected to the User Port.
The 6522 VIA is quite a complex device controled by 16 registers. The
VIA-B registers are mapped onto Sheila addresses &60 to &6F (ie. &FE60 to
&FE6F) as shown in figure 1.
Address Description Designation
+-------+-------------------------------------+-------------+
| &FE6F | Data register A (no handshake) | DRA |
+-------+-------------------------------------+-------------+
| &FE6E | Interrupt enable register | IER |
+-------+-------------------------------------+-------------+
| &FE6D | Interrupt flag register | IFR |
+-------+-------------------------------------+-------------+
| &FE6C | Peripheral control register | PCR |
+-------+-------------------------------------+-------------+
| &FE6B | Auxiliary control register | ACR |
+-------+-------------------------------------+-------------+
| &FE6A | Shift register | SR |
+-------+-------------------------------------+-------------+
| &FE69 | Timer 2 initiate count | T2CH |
+-------+-------------------------------------+-------------+
| &FE68 | Timer 2 write latch, read counter | T2CL |
+-------+-------------------------------------+-------------+
| &FE67 | Timer 1 load latch, high byte | T1LH |
+-------+-------------------------------------+-------------+
| &FE66 | Timer 1 load latch, low byte | T1LL |
+-------+-------------------------------------+-------------+
| &FE65 | Timer 1 initiate count | T1CH |
+-------+-------------------------------------+-------------+
| &FE64 | Timer 1 write latch, read counter | T1CL |
+-------+-------------------------------------+-------------+
| &FE63 | Data direction register A | DDRA |
+-------+-------------------------------------+-------------+
| &FE62 | Data direction register B | DDRB |
+-------+-------------------------------------+-------------+
| &FE61 | Data register A | DRA |
+-------+-------------------------------------+-------------+
| &FE60 | Data register B | DRB |
+-------+-------------------------------------+-------------+
Figure 1 The VIA-B registers
-------- -------------------
Five of these 16 registers are of interest when using a mouse. They
are data register B (DRB, &FE60), data direction register B (DDRB, &FE62),
the peripheral control register (PCR, &FE6C), the interrupt flag register
(IFR, &FE6D), and the interrupt enable register (IER, &FE6E). The
auxillary control register (ACR, &FE6B) is also of passing interest.
Both the system VIA and the user VIA have 20 I/O lines grouped into an A
side and a B side of 10 lines each. These 10 lines are divided into 8 data
lines and 2 handshake lines. The data lines are called PA0 to PA7 on the A
side and PB0 to PB7 on the B side. Data lines PA0 to PA7 can be read from
or written to data register A (&FE61) and data lines PB0 to PB7 can be
read from or written to data register B (&FE60). The B side of VIA-B is
known as the User Port and PB0 to PB7 are the User Port data lines. The
handshake lines are called CA1 and CA2 on the A side and CB1 and CB2 on
the B side. CB1 and CB2 are the User Port handshake lines.
The User Port data register, DRB, can be made an input register by writing
the number zero into DDRB. Clearing a bit in DDRB makes the eqivalent bit
in DRB an input. Setting a bit in DDRB makes the equivalent bit in DRB an
output.
The peripheral control register is used to control the use of the
handshake lines. The VIA-B PCR and the interpretation of its bits is shown
in figure 2.
bit 7 6 5 4 3 2 1 0
+-------+-------+-------+-----------+-------+-------+-------+-----------+
| CB2 control |CB1 control| CA2 Control |CA1 control|
| User Port | User Port | Printer strobe |Printer ack|
+-------+-------+-------+-----------+-------+-------+-------+-----------+
Bit Interpretation if bit clear (0) Interpretation if bit set (1)
+---+---------------------------------+---------------------------------+
| 0 |Set bit 1 of IFR on -ve going CA1|Set bit 1 of IFR on +ve going CA1|
+---+---------------------------------+---------------------------------+
| 1 | DRA selected to clear interrupt | Interrupt not cleared by DRA |
+---+---------------------------------+---------------------------------+
| 2 |Set bit 0 of IFR on -ve going CA2|Set bit 0 of IFR on +ve going CA2|
+---+---------------------------------+---------------------------------+
| 3 | Bit 3 always set | Set CA2 to output (always set) |
+---+---------------------------------+---------------------------------+
| 4 |Set bit 4 of IFR on -ve going CB1|Set bit 4 of IFR on +ve going CB1|
+---+---------------------------------+---------------------------------+
| 5 | DRB selected to clear interrupt | Interrupt not cleared by DRB |
+---+---------------------------------+---------------------------------+
| 6 |Set bit 3 of IFR on -ve going CB2|Set bit 3 of IFR on +ve going CB2|
+---+---------------------------------+---------------------------------+
| 7 | Set CB2 to input mode | Set CB2 to output mode |
+---+---------------------------------+---------------------------------+
Figure 2 The peripheral control register
-------- -------------------------------
Both CB1 and CB2 are used as inputs by an AMX compatible mouse. When using
interrupt driven mouse software you will need to set bits 4 and 6 and
clear bits 5 and 7 of the PCR. This means that a positive going signal on
either CB1 or CB2 will generate an IQR interrupt and that interrupt will
be cleared by reading data register B, ie. by reading the data lines. Bit
7 of the PCR is clear to make CB2 an input, CB1 is an input line by
default. A program which alters bits 4 to 7 of the PCR must not alter bits
0 to 3 which are used by the parallel printer interface. The following
code can be used to set bits 4 and 6 and clear bits 5 and 7 of the PCR:
LDA &FE6C \ load A with the contents of the peripheral control register
AND #&0F \ AND with %00001111, ie. clear bit 4-7
ORA #&50 \ OR with %01010000, ie. set bits 4 and 6
STA &FE6C \ store A in the peripheral control register
Mouse generated interrupts are enabled by setting bits 3 and 4 of the
interrupt enable register. Setting these bits uses an odd method. To alter
a bit in the IER you must write a number to the IER with a 1 in the same
bit position. If bit 7 of the number is set then the selected bit (or
bits) will also be set to 1. If bit 7 of the number is clear then the
selected bit (or bits) will be cleared. The selected bits (0 to 6) are set
to the same state as bit 7. To set bits 3 and 4 of the IER you have to
write the number &98 (%10011000) into the IER. Bits 3 and 4 will then take
the value of bit 7 and will be set, enabling interrupts from CB1 and CB2.
When bits 3 and 4 of the IER are set then a positive transition on CB1
will set bit 4 of the interrupt flag register and generate an IRQ
interrupt. A positive transition on CB2 will set bit 3 of the IFR and
generate an IQR interrupt. These interrupts can be recognised because
either bits 7 and 3 of IFR or bits 7 and 4 of the IFR will be set.
Mouse generated interrupts are disabled by writing the number &08
(%00011000) into the IER. This clears bits 3 and 4 of the IER so that a
positive going transition on CB1 or CB2 will still set either bit 4 or bit
3 of the IFR but it will not generate an IRQ interrupt. Mouse generated
interrupts can be enabled with ?&FE6E=&98 or *FX 151,78,152 and disabled
with ?&FE6E=&18 or *FX 151,78,24
The interrupt enable register and the interrupt flag register work as a
pair and the flag register must be interrogated by a program to see if a
mouse connected to the User Port is the source of an interrupt. The
interpretation of the bits in the IFR is tabulated in figure 3 which shows
that bits 7 and 3 or 7 and 4 of the IFR will be set if a mouse connected
to the User Port is the source of an interrupt.
7 6 5 4 3 2 1 0
+---------+-----+-----+-----+-----+-----+-----+-----+
&FE6E |Set/Clear| T1 | T2 | CB1 | CB2 | SR | CA1 | CA2 | IER
+---------+-----+-----+-----+-----+-----+-----+-----+
&FE6D | IRQ | T1 | T2 | CB1 | CB2 | SR | CA1 | CA2 | IFR
+---------+-----+-----+-----+-----+-----+-----+-----+
Bit Cause of interrupt Interpretation
+---+-------------------------+-----------------------------------------+
| 0 | Change of signal on CA2 | Printer strobe |
+---+-------------------------+-----------------------------------------+
| 1 | Change of signal on CA1 | Printer acknowledge |
+---+-------------------------+-----------------------------------------+
| 2 | Completion of 8 shifts | |
| | in the shift register | |
+---+-------------------------+-----------------------------------------+
| 3 | Change of signal on CB2 | Mouse movement in the Y direction |
+---+-------------------------+-----------------------------------------+
| 4 | Change of signal on CB1 | Mouse movement in the X direction |
+---+-------------------------+-----------------------------------------+
| 5 | Timer 2 complete | |
+---+-------------------------+-----------------------------------------+
| 6 | Timer 1 complete | |
+---+-------------------------+-----------------------------------------+
| 7 | Any bit, 0 to 6, is set | One of the above interrupts has occured |
+---+-------------------------+-----------------------------------------+
Figure 3. The interpretation of VIA-B IFR (mouse connected to User Port)
--------- --------------------------------------------------------------
An interrupt handling routine should interogate bits 7, 3 and 4 of the IFR
to find out if a mouse connected to the User Port is the source of an IRQ
interrupt. Bits 7 and 3 will be set if the mouse is moved up or down and
bits 7 and 4 will be set if the mouse is moved from side to side. If a
mouse is the source of an interrupt then the interrupt must be cleared by
reading the contents of DRB (because bit 5 of the PCR is clear). You can
therefore read the data lines and clear the interrupt at the same time.
The plane of movement of a mouse can be determined from the IFR but the
direction of change (either increasing or decreasing) has to be found from
the data lines. A movement either up or down will set bit 3 of the IFR. If
bit 3 of the IFR is set your program should test bit 2 of data register B.
If bit 2 of DRB is set then Y is decreasing but if it is clear then Y is
increasing. A movement from side to side will set bit 4 of the IFR. Your
program should then test bit 0 of DRB. If it is set then X is decreasing,
if it is clear then X is increasing.
The data lines also give the status of the mouse buttons. Pressing the
right button clears bit 7 of DRB, pressing the centre button clears bit 6
and the left button clears bit 5.
The auxiliary control register is of passing interest because it can
either set or clear latching the data lines on a signal from CB1. This
would be quite useful if the mouse had been designed to use only one
handshake line but, because it uses both CB1 and CB2 as inputs, the data
lines can only be latched for movement in the X direction. This seems to
be a pity but the AMX design is an industry standard for BBC computers and
we have to live with it. You can clear bit 1 of the ACR to disable
latching the data lines prior to using a mouse. The ACR is cleared by
pressing the Break key.
The status of the IFR and DRB can be demonstrated with the program
TESTMOU. This program does not enable the mouse generated interrupts but
it does show the continuously updated binary status of the IFR and DRB.
Connect your mouse to the computer, switch on, chain the program TESTMOU
and move the mouse around. Bit 7 of the IFR is always clear because
interrupts have not been enabled. Move the mouse quickly to either the
left or right. You should see CB1 set while it is moving and clear as soon
as it stops. Similarly move the mouse quickly up and down to see the same
effect on CB2. At the same time you will see bits 0 and 2 of DRB changing
state. You can also see the effect that pressing the mouse buttons has on
DRB.
This module has explained where to find the data produced by a mouse. The
following modules will explain how these data can be interpreted and used.
10 REM> TESTMOU
20 DIM mcode &100 :REM: machine code at mcode
30 escape=&FF :REM: escape flag
40 drb=&FE60 :REM: data register B
50 ddrb=&FE62 :REM: data direction register B
60 ifr=&FE6D :REM: interrupt flag register
70 oswrch=&FFEE
80 osbyte=&FFF4
90 FOR pass=0 TO 2 STEP 2
100 P%=mcode
110 [ OPT pass
120 LDA #&00
130 STA ddrb \ data register B = input
140 .mainloop
150 LDX #16
160 LDY #16
170 JSR vdu \ VDU 31,16,16
180 LDA drb \ data register B
190 JSR binary \ print DRB in binary
200 LDX #16
210 LDY #18
220 JSR vdu \ VDU 31,16,18
230 LDA ifr \ interrupt flag register
240 JSR binary \ print IFR in binary
250 LDA escape \ poll the escape flag
260 BPL mainloop \ loop if escape not pressed
270 LDA #&7E \ acknowledge detection of an Escape condition
280 JMP osbyte \ acknowledge Escape and return to BASIC
290 .binary
300 LDX #&08 \ bit counter
310 .nextbit
320 ASL A \ next bit into carry flag
330 PHA \ save the rest of the byte
340 LDA #ASC("0") \ if carry clear print 0
350 ADC #&00 \ if carry set add 1
360 JSR oswrch \ print 0 or 1
370 PLA \ restore the rest of the byte
380 DEX \ decrement bit counter
390 BNE nextbit \ branch for next bit
400 RTS
410 .vdu
420 LDA #31
430 JSR oswrch \ VDU 31
440 TXA
450 JSR oswrch \ VDU X
460 TYA
470 JMP oswrch \ VDU Y and return
480 ]
490 NEXT
500 MODE7
510 VDU23,1,0;0;0;0;
520 mouse$=CHR$141+CHR$132+CHR$157+CHR$131
+"User port input and status bytes "+CHR$156
530 PRINTTAB(0,5)mouse$
540 PRINTTAB(0,6)mouse$
550 PRINTTAB(16,14)"76543210"
560 PRINTTAB(9,16)"&FE60 % DRB"
570 PRINTTAB(9,18)"&FE6D % IFR"
580 PRINTTAB(19,20)"CC"
590 PRINTTAB(19,21)"BB"
600 PRINTTAB(19,22)"12"
610 CALL mcode
620 VDU31,0,24
630 VDU23,1,1;0;0;0;
640 END
00000000 55 73 69 6e 67 20 61 20 6d 6f 75 73 65 20 77 69 |Using a mouse wi|
00000010 74 68 20 74 68 65 20 42 42 43 20 6d 69 63 72 6f |th the BBC micro|
00000020 63 6f 6d 70 75 74 65 72 20 2d 20 62 79 20 2d 20 |computer - by - |
00000030 47 6f 72 64 6f 6e 20 48 6f 72 73 69 6e 67 74 6f |Gordon Horsingto|
00000040 6e 0d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |n.--------------|
00000050 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00000080 2d 2d 2d 0d 0d 4d 6f 64 75 6c 65 20 30 2e 20 49 |---..Module 0. I|
00000090 6e 74 72 6f 64 75 63 74 69 6f 6e 0d 2d 2d 2d 2d |ntroduction.----|
000000a0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
000000b0 2d 2d 0d 0d 41 6e 20 41 4d 58 20 63 6f 6d 70 61 |--..An AMX compa|
000000c0 74 69 62 6c 65 20 6d 6f 75 73 65 20 63 61 6e 20 |tible mouse can |
000000d0 62 65 20 75 73 65 64 20 77 69 74 68 20 74 68 65 |be used with the|
000000e0 20 42 42 43 20 42 2c 20 42 42 43 20 42 2b 20 61 | BBC B, BBC B+ a|
000000f0 6e 64 20 4d 61 73 74 65 72 0d 73 65 72 69 65 73 |nd Master.series|
00000100 20 63 6f 6d 70 75 74 65 72 73 2e 20 54 68 69 73 | computers. This|
00000110 20 6d 6f 64 75 6c 65 20 69 6e 74 72 6f 64 75 63 | module introduc|
00000120 65 73 20 61 20 62 6c 6f 63 6b 20 6f 66 20 73 65 |es a block of se|
00000130 76 65 6e 20 6d 6f 64 75 6c 65 73 20 77 68 69 63 |ven modules whic|
00000140 68 0d 64 65 61 6c 20 77 69 74 68 20 74 68 65 20 |h.deal with the |
00000150 64 65 73 69 67 6e 20 6f 66 20 73 6f 66 74 77 61 |design of softwa|
00000160 72 65 20 77 68 69 63 68 20 77 69 6c 6c 20 61 6c |re which will al|
00000170 6c 6f 77 20 61 20 6d 6f 75 73 65 20 74 6f 20 62 |low a mouse to b|
00000180 65 20 75 73 65 64 0d 77 69 74 68 6f 75 74 20 69 |e used.without i|
00000190 74 73 20 6d 61 6e 75 66 61 63 74 75 72 65 72 73 |ts manufacturers|
000001a0 20 63 6f 6e 74 72 6f 6c 20 52 4f 4d 20 6f 72 20 | control ROM or |
000001b0 61 6e 79 20 6f 74 68 65 72 20 61 6c 74 65 72 6e |any other altern|
000001c0 61 74 69 76 65 20 73 6f 66 74 77 61 72 65 2e 20 |ative software. |
000001d0 41 0d 6d 6f 75 73 65 20 63 61 6e 20 62 65 20 62 |A.mouse can be b|
000001e0 6f 75 67 68 74 20 77 69 74 68 6f 75 74 20 61 20 |ought without a |
000001f0 63 6f 6e 74 72 6f 6c 20 52 4f 4d 20 61 6e 64 2c |control ROM and,|
00000200 20 69 66 20 79 6f 75 20 64 6f 6e 27 74 20 77 61 | if you don't wa|
00000210 6e 74 20 74 6f 20 75 73 65 0d 74 68 65 20 61 72 |nt to use.the ar|
00000220 74 20 73 6f 66 74 77 61 72 65 20 74 68 61 74 20 |t software that |
00000230 74 68 65 73 65 20 52 4f 4d 73 20 63 6f 6e 74 61 |these ROMs conta|
00000240 69 6e 2c 20 74 68 65 6e 20 62 75 79 69 6e 67 20 |in, then buying |
00000250 6a 75 73 74 20 74 68 65 20 68 61 72 64 77 61 72 |just the hardwar|
00000260 65 0d 68 61 6c 76 65 73 20 74 68 65 20 63 6f 73 |e.halves the cos|
00000270 74 20 6f 66 20 6f 77 6e 69 6e 67 20 61 20 6d 6f |t of owning a mo|
00000280 75 73 65 2e 20 49 20 68 6f 70 65 20 74 6f 20 64 |use. I hope to d|
00000290 65 6d 6f 6e 73 74 72 61 74 65 20 74 68 61 74 20 |emonstrate that |
000002a0 74 68 65 20 73 6f 66 74 77 61 72 65 0d 79 6f 75 |the software.you|
000002b0 20 63 61 6e 20 65 61 73 69 6c 79 20 63 72 65 61 | can easily crea|
000002c0 74 65 20 79 6f 75 72 73 65 6c 66 20 63 61 6e 20 |te yourself can |
000002d0 62 65 20 6a 75 73 74 20 61 73 20 75 73 65 66 75 |be just as usefu|
000002e0 6c 20 61 73 20 74 68 65 20 73 6f 66 74 77 61 72 |l as the softwar|
000002f0 65 20 74 68 61 74 0d 74 68 65 20 6d 61 6e 75 66 |e that.the manuf|
00000300 61 63 74 75 72 65 72 73 20 73 75 70 70 6c 79 2e |acturers supply.|
00000310 0d 0d 54 68 65 20 73 65 76 65 6e 20 6d 6f 64 75 |..The seven modu|
00000320 6c 65 73 20 61 72 65 20 69 6e 20 66 69 6c 65 73 |les are in files|
00000330 20 6e 61 6d 65 64 20 54 2f 4d 4f 55 30 30 20 74 | named T/MOU00 t|
00000340 6f 20 54 2f 4d 4f 55 30 36 2e 20 54 68 65 20 66 |o T/MOU06. The f|
00000350 6f 6c 6c 6f 77 69 6e 67 0d 74 6f 70 69 63 73 20 |ollowing.topics |
00000360 77 69 6c 6c 20 62 65 20 63 6f 76 65 72 65 64 20 |will be covered |
00000370 69 6e 20 74 68 65 73 65 20 6d 6f 64 75 6c 65 73 |in these modules|
00000380 2e 0d 0d 0d 4d 6f 64 75 6c 65 20 30 2e 20 54 68 |....Module 0. Th|
00000390 69 73 20 6d 6f 64 75 6c 65 2e 20 49 6e 74 72 6f |is module. Intro|
000003a0 64 75 63 74 69 6f 6e 20 61 6e 64 20 74 68 65 20 |duction and the |
000003b0 55 73 65 72 20 50 6f 72 74 2e 0d 20 20 20 20 20 |User Port.. |
000003c0 20 20 20 20 20 50 72 6f 67 72 61 6d 3a 20 54 45 | Program: TE|
000003d0 53 54 4d 4f 55 0d 0d 4d 6f 64 75 6c 65 20 31 2e |STMOU..Module 1.|
000003e0 20 52 65 61 64 69 6e 67 20 74 68 65 20 6d 6f 75 | Reading the mou|
000003f0 73 65 20 63 6f 6f 72 64 69 6e 61 74 65 73 2e 0d |se coordinates..|
00000400 20 20 20 20 20 20 20 20 20 20 50 72 6f 67 72 61 | Progra|
00000410 6d 3a 20 4d 4f 55 53 45 0d 0d 4d 6f 64 75 6c 65 |m: MOUSE..Module|
00000420 20 32 2e 20 54 75 62 65 20 63 6f 6d 70 61 74 69 | 2. Tube compati|
00000430 62 6c 65 20 6d 6f 75 73 65 20 73 6f 66 74 77 61 |ble mouse softwa|
00000440 72 65 2e 0d 20 20 20 20 20 20 20 20 20 20 50 72 |re.. Pr|
00000450 6f 67 72 61 6d 3a 20 53 50 4d 4f 55 53 45 0d 0d |ogram: SPMOUSE..|
00000460 4d 6f 64 75 6c 65 20 33 2e 20 50 6f 6c 6c 69 6e |Module 3. Pollin|
00000470 67 20 74 68 65 20 6d 6f 75 73 65 20 62 75 74 74 |g the mouse butt|
00000480 6f 6e 73 2e 0d 20 20 20 20 20 20 20 20 20 20 50 |ons.. P|
00000490 72 6f 67 72 61 6d 73 3a 20 45 56 45 4e 54 20 42 |rograms: EVENT B|
000004a0 55 54 54 4f 4e 53 0d 0d 4d 6f 64 75 6c 65 20 34 |UTTONS..Module 4|
000004b0 2e 20 52 65 61 64 69 6e 67 20 61 20 6d 6f 75 73 |. Reading a mous|
000004c0 65 20 77 69 74 68 20 74 68 65 20 6e 65 67 61 74 |e with the negat|
000004d0 69 76 65 20 49 4e 4b 45 59 20 61 6e 64 20 74 68 |ive INKEY and th|
000004e0 65 20 6b 65 79 62 6f 61 72 64 20 73 63 61 6e 2e |e keyboard scan.|
000004f0 0d 20 20 20 20 20 20 20 20 20 20 50 72 6f 67 72 |. Progr|
00000500 61 6d 73 3a 20 4e 45 57 4b 45 59 53 20 4c 4f 41 |ams: NEWKEYS LOA|
00000510 44 45 52 20 4e 45 57 53 43 41 4e 0d 0d 4d 6f 64 |DER NEWSCAN..Mod|
00000520 75 6c 65 20 35 2e 20 52 65 61 64 69 6e 67 20 61 |ule 5. Reading a|
00000530 20 6d 6f 75 73 65 20 77 69 74 68 20 74 68 65 20 | mouse with the |
00000540 42 41 53 49 43 20 41 44 56 41 4c 20 63 6f 6d 6d |BASIC ADVAL comm|
00000550 61 6e 64 2e 0d 20 20 20 20 20 20 20 20 20 20 50 |and.. P|
00000560 72 6f 67 72 61 6d 3a 20 41 4e 4d 4f 55 53 45 0d |rogram: ANMOUSE.|
00000570 0d 4d 6f 64 75 6c 65 20 36 2e 20 55 73 69 6e 67 |.Module 6. Using|
00000580 20 53 69 64 65 77 61 79 73 20 52 41 4d 20 66 6f | Sideways RAM fo|
00000590 72 20 6d 6f 75 73 65 20 73 6f 66 74 77 61 72 65 |r mouse software|
000005a0 2e 0d 20 20 20 20 20 20 20 20 20 20 50 72 6f 67 |.. Prog|
000005b0 72 61 6d 73 3a 20 53 57 4d 4f 55 53 45 20 53 57 |rams: SWMOUSE SW|
000005c0 52 4d 49 43 45 20 53 57 54 45 53 54 0d 0d 54 68 |RMICE SWTEST..Th|
000005d0 65 20 6c 61 74 65 72 20 6d 6f 64 75 6c 65 73 20 |e later modules |
000005e0 64 65 76 65 6c 6f 70 20 74 68 65 20 69 64 65 61 |develop the idea|
000005f0 73 20 61 6e 64 20 74 65 63 68 6e 69 71 75 65 73 |s and techniques|
00000600 20 64 65 73 63 72 69 62 65 64 20 69 6e 20 74 68 | described in th|
00000610 65 0d 65 61 72 6c 69 65 72 20 6d 6f 64 75 6c 65 |e.earlier module|
00000620 73 20 61 6e 64 20 66 6f 72 20 74 68 69 73 20 72 |s and for this r|
00000630 65 61 73 6f 6e 20 74 68 65 79 20 6e 65 65 64 20 |eason they need |
00000640 74 6f 20 62 65 20 77 6f 72 6b 65 64 20 74 68 72 |to be worked thr|
00000650 6f 75 67 68 20 66 72 6f 6d 0d 6d 6f 64 75 6c 65 |ough from.module|
00000660 20 30 20 74 6f 20 6d 6f 64 75 6c 65 20 36 20 72 | 0 to module 6 r|
00000670 61 74 68 65 72 20 74 68 61 6e 20 75 73 65 64 20 |ather than used |
00000680 61 73 20 61 20 72 65 66 65 72 65 6e 63 65 20 67 |as a reference g|
00000690 75 69 64 65 2e 20 49 74 20 69 73 0d 6e 65 63 65 |uide. It is.nece|
000006a0 73 73 61 72 79 20 74 6f 20 68 61 76 65 20 65 69 |ssary to have ei|
000006b0 74 68 65 72 20 42 41 53 49 43 20 32 20 6f 72 20 |ther BASIC 2 or |
000006c0 42 41 53 49 43 20 34 20 61 6e 64 20 6f 70 65 72 |BASIC 4 and oper|
000006d0 61 74 69 6e 67 20 73 79 73 74 65 6d 20 31 2e 32 |ating system 1.2|
000006e0 30 20 28 6f 72 0d 68 69 67 68 65 72 29 20 69 6e |0 (or.higher) in|
000006f0 73 74 61 6c 6c 65 64 20 69 6e 20 79 6f 75 72 20 |stalled in your |
00000700 63 6f 6d 70 75 74 65 72 2e 0d 0d 0d 54 68 65 20 |computer....The |
00000710 55 73 65 72 20 50 6f 72 74 0d 2d 2d 2d 2d 2d 2d |User Port.------|
00000720 2d 2d 2d 2d 2d 2d 2d 0d 0d 54 68 65 72 65 20 61 |-------..There a|
00000730 72 65 20 74 77 6f 20 36 35 32 32 20 56 49 41 73 |re two 6522 VIAs|
00000740 20 69 6e 20 74 68 65 20 42 42 43 20 42 2e 20 56 | in the BBC B. V|
00000750 49 41 2d 41 20 69 73 20 75 73 65 64 20 66 6f 72 |IA-A is used for|
00000760 20 69 6e 74 65 72 6e 61 6c 20 66 75 6e 63 74 69 | internal functi|
00000770 6f 6e 73 0d 61 6e 64 20 74 68 65 20 6a 6f 79 73 |ons.and the joys|
00000780 74 69 63 6b 20 66 69 72 65 20 62 75 74 74 6f 6e |tick fire button|
00000790 73 20 61 6e 64 20 69 73 20 75 73 75 61 6c 6c 79 |s and is usually|
000007a0 20 63 61 6c 6c 65 64 20 74 68 65 20 73 79 73 74 | called the syst|
000007b0 65 6d 20 56 49 41 2e 20 56 49 41 2d 42 0d 70 72 |em VIA. VIA-B.pr|
000007c0 6f 76 69 64 65 73 20 74 68 65 20 70 61 72 61 6c |ovides the paral|
000007d0 6c 65 6c 20 70 72 69 6e 74 65 72 20 69 6e 74 65 |lel printer inte|
000007e0 72 66 61 63 65 20 61 6e 64 20 74 68 65 20 55 73 |rface and the Us|
000007f0 65 72 20 50 6f 72 74 2e 20 41 6e 20 41 4d 58 0d |er Port. An AMX.|
00000800 63 6f 6d 70 61 74 69 62 6c 65 20 6d 6f 75 73 65 |compatible mouse|
00000810 20 69 73 20 63 6f 6e 6e 65 63 74 65 64 20 74 6f | is connected to|
00000820 20 74 68 65 20 55 73 65 72 20 50 6f 72 74 2e 0d | the User Port..|
00000830 0d 54 68 65 20 36 35 32 32 20 56 49 41 20 69 73 |.The 6522 VIA is|
00000840 20 71 75 69 74 65 20 61 20 63 6f 6d 70 6c 65 78 | quite a complex|
00000850 20 64 65 76 69 63 65 20 63 6f 6e 74 72 6f 6c 65 | device controle|
00000860 64 20 62 79 20 31 36 20 72 65 67 69 73 74 65 72 |d by 16 register|
00000870 73 2e 20 54 68 65 0d 56 49 41 2d 42 20 72 65 67 |s. The.VIA-B reg|
00000880 69 73 74 65 72 73 20 61 72 65 20 6d 61 70 70 65 |isters are mappe|
00000890 64 20 6f 6e 74 6f 20 53 68 65 69 6c 61 20 61 64 |d onto Sheila ad|
000008a0 64 72 65 73 73 65 73 20 26 36 30 20 74 6f 20 26 |dresses &60 to &|
000008b0 36 46 20 28 69 65 2e 20 26 46 45 36 30 20 74 6f |6F (ie. &FE60 to|
000008c0 0d 26 46 45 36 46 29 20 61 73 20 73 68 6f 77 6e |.&FE6F) as shown|
000008d0 20 69 6e 20 66 69 67 75 72 65 20 31 2e 0d 0d 0d | in figure 1....|
000008e0 0d 20 20 20 20 20 20 20 20 41 64 64 72 65 73 73 |. Address|
000008f0 20 20 20 20 20 20 20 20 20 20 20 20 20 44 65 73 | Des|
00000900 63 72 69 70 74 69 6f 6e 20 20 20 20 20 20 20 20 |cription |
00000910 20 20 20 20 20 20 20 20 44 65 73 69 67 6e 61 74 | Designat|
00000920 69 6f 6e 0d 20 20 20 20 20 20 20 2b 2d 2d 2d 2d |ion. +----|
00000930 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |---+------------|
00000940 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00000950 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d |---------+------|
00000960 2d 2d 2d 2d 2d 2d 2d 2b 0d 20 20 20 20 20 20 20 |-------+. |
00000970 7c 20 26 46 45 36 46 20 7c 20 44 61 74 61 20 72 || &FE6F | Data r|
00000980 65 67 69 73 74 65 72 20 41 20 28 6e 6f 20 68 61 |egister A (no ha|
00000990 6e 64 73 68 61 6b 65 29 20 20 20 20 20 20 7c 20 |ndshake) | |
000009a0 44 52 41 20 20 20 20 20 20 20 20 20 7c 0d 20 20 |DRA |. |
000009b0 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d | +-------+--|
000009c0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
000009e0 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |---+------------|
000009f0 2d 2b 0d 20 20 20 20 20 20 20 7c 20 26 46 45 36 |-+. | &FE6|
00000a00 45 20 7c 20 49 6e 74 65 72 72 75 70 74 20 65 6e |E | Interrupt en|
00000a10 61 62 6c 65 20 72 65 67 69 73 74 65 72 20 20 20 |able register |
00000a20 20 20 20 20 20 20 20 20 7c 20 49 45 52 20 20 20 | | IER |
00000a30 20 20 20 20 20 20 7c 0d 20 20 20 20 20 20 20 2b | |. +|
00000a40 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d |-------+--------|
00000a50 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00000a60 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d |-------------+--|
00000a70 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 20 20 20 |-----------+. |
00000a80 20 20 20 20 7c 20 26 46 45 36 44 20 7c 20 49 6e | | &FE6D | In|
00000a90 74 65 72 72 75 70 74 20 66 6c 61 67 20 72 65 67 |terrupt flag reg|
00000aa0 69 73 74 65 72 20 20 20 20 20 20 20 20 20 20 20 |ister |
00000ab0 20 20 7c 20 49 46 52 20 20 20 20 20 20 20 20 20 | | IFR |
00000ac0 7c 0d 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d ||. +------|
00000ad0 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |-+--------------|
00000ae0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00000af0 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d |-------+--------|
00000b00 2d 2d 2d 2d 2d 2b 0d 20 20 20 20 20 20 20 7c 20 |-----+. | |
00000b10 26 46 45 36 43 20 7c 20 50 65 72 69 70 68 65 72 |&FE6C | Peripher|
00000b20 61 6c 20 63 6f 6e 74 72 6f 6c 20 72 65 67 69 73 |al control regis|
00000b30 74 65 72 20 20 20 20 20 20 20 20 20 7c 20 50 43 |ter | PC|
00000b40 52 20 20 20 20 20 20 20 20 20 7c 0d 20 20 20 20 |R |. |
00000b50 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d | +-------+----|
00000b60 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00000b80 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b |-+-------------+|
00000b90 0d 20 20 20 20 20 20 20 7c 20 26 46 45 36 42 20 |. | &FE6B |
00000ba0 7c 20 41 75 78 69 6c 69 61 72 79 20 63 6f 6e 74 || Auxiliary cont|
00000bb0 72 6f 6c 20 72 65 67 69 73 74 65 72 20 20 20 20 |rol register |
00000bc0 20 20 20 20 20 20 7c 20 41 43 52 20 20 20 20 20 | | ACR |
00000bd0 20 20 20 20 7c 0d 20 20 20 20 20 20 20 2b 2d 2d | |. +--|
00000be0 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |-----+----------|
00000bf0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00000c00 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d |-----------+----|
00000c10 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 20 20 20 20 20 |---------+. |
00000c20 20 20 7c 20 26 46 45 36 41 20 7c 20 53 68 69 66 | | &FE6A | Shif|
00000c30 74 20 72 65 67 69 73 74 65 72 20 20 20 20 20 20 |t register |
00000c40 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
00000c50 7c 20 53 52 20 20 20 20 20 20 20 20 20 20 7c 0d || SR |.|
00000c60 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2b | +-------+|
00000c70 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00000c90 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |-----+----------|
00000ca0 2d 2d 2d 2b 0d 20 20 20 20 20 20 20 7c 20 26 46 |---+. | &F|
00000cb0 45 36 39 20 7c 20 54 69 6d 65 72 20 32 20 69 6e |E69 | Timer 2 in|
00000cc0 69 74 69 61 74 65 20 63 6f 75 6e 74 20 20 20 20 |itiate count |
00000cd0 20 20 20 20 20 20 20 20 20 20 7c 20 54 32 43 48 | | T2CH|
00000ce0 20 20 20 20 20 20 20 20 7c 0d 20 20 20 20 20 20 | |. |
00000cf0 20 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d | +-------+------|
00000d00 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00000d10 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b |---------------+|
00000d20 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 20 |-------------+. |
00000d30 20 20 20 20 20 20 7c 20 26 46 45 36 38 20 7c 20 | | &FE68 | |
00000d40 54 69 6d 65 72 20 32 20 77 72 69 74 65 20 6c 61 |Timer 2 write la|
00000d50 74 63 68 2c 20 72 65 61 64 20 63 6f 75 6e 74 65 |tch, read counte|
00000d60 72 20 20 20 7c 20 54 32 43 4c 20 20 20 20 20 20 |r | T2CL |
00000d70 20 20 7c 0d 20 20 20 20 20 20 20 2b 2d 2d 2d 2d | |. +----|
00000d80 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |---+------------|
00000d90 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00000da0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d |---------+------|
00000db0 2d 2d 2d 2d 2d 2d 2d 2b 0d 20 20 20 20 20 20 20 |-------+. |
00000dc0 7c 20 26 46 45 36 37 20 7c 20 54 69 6d 65 72 20 || &FE67 | Timer |
00000dd0 31 20 6c 6f 61 64 20 6c 61 74 63 68 2c 20 68 69 |1 load latch, hi|
00000de0 67 68 20 62 79 74 65 20 20 20 20 20 20 20 7c 20 |gh byte | |
00000df0 54 31 4c 48 20 20 20 20 20 20 20 20 7c 0d 20 20 |T1LH |. |
00000e00 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d | +-------+--|
00000e10 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00000e30 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |---+------------|
00000e40 2d 2b 0d 20 20 20 20 20 20 20 7c 20 26 46 45 36 |-+. | &FE6|
00000e50 36 20 7c 20 54 69 6d 65 72 20 31 20 6c 6f 61 64 |6 | Timer 1 load|
00000e60 20 6c 61 74 63 68 2c 20 6c 6f 77 20 62 79 74 65 | latch, low byte|
00000e70 20 20 20 20 20 20 20 20 7c 20 54 31 4c 4c 20 20 | | T1LL |
00000e80 20 20 20 20 20 20 7c 0d 20 20 20 20 20 20 20 2b | |. +|
00000e90 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d |-------+--------|
00000ea0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00000eb0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d |-------------+--|
00000ec0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 20 20 20 |-----------+. |
00000ed0 20 20 20 20 7c 20 26 46 45 36 35 20 7c 20 54 69 | | &FE65 | Ti|
00000ee0 6d 65 72 20 31 20 69 6e 69 74 69 61 74 65 20 63 |mer 1 initiate c|
00000ef0 6f 75 6e 74 20 20 20 20 20 20 20 20 20 20 20 20 |ount |
00000f00 20 20 7c 20 54 31 43 48 20 20 20 20 20 20 20 20 | | T1CH |
00000f10 7c 0d 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d ||. +------|
00000f20 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |-+--------------|
00000f30 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00000f40 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d |-------+--------|
00000f50 2d 2d 2d 2d 2d 2b 0d 20 20 20 20 20 20 20 7c 20 |-----+. | |
00000f60 26 46 45 36 34 20 7c 20 54 69 6d 65 72 20 31 20 |&FE64 | Timer 1 |
00000f70 77 72 69 74 65 20 6c 61 74 63 68 2c 20 72 65 61 |write latch, rea|
00000f80 64 20 63 6f 75 6e 74 65 72 20 20 20 7c 20 54 31 |d counter | T1|
00000f90 43 4c 20 20 20 20 20 20 20 20 7c 0d 20 20 20 20 |CL |. |
00000fa0 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d | +-------+----|
00000fb0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00000fd0 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b |-+-------------+|
00000fe0 0d 20 20 20 20 20 20 20 7c 20 26 46 45 36 33 20 |. | &FE63 |
00000ff0 7c 20 44 61 74 61 20 64 69 72 65 63 74 69 6f 6e || Data direction|
00001000 20 72 65 67 69 73 74 65 72 20 41 20 20 20 20 20 | register A |
00001010 20 20 20 20 20 20 7c 20 44 44 52 41 20 20 20 20 | | DDRA |
00001020 20 20 20 20 7c 0d 20 20 20 20 20 20 20 2b 2d 2d | |. +--|
00001030 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |-----+----------|
00001040 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001050 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d |-----------+----|
00001060 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 20 20 20 20 20 |---------+. |
00001070 20 20 7c 20 26 46 45 36 32 20 7c 20 44 61 74 61 | | &FE62 | Data|
00001080 20 64 69 72 65 63 74 69 6f 6e 20 72 65 67 69 73 | direction regis|
00001090 74 65 72 20 42 20 20 20 20 20 20 20 20 20 20 20 |ter B |
000010a0 7c 20 44 44 52 42 20 20 20 20 20 20 20 20 7c 0d || DDRB |.|
000010b0 20 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2b | +-------+|
000010c0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
000010e0 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |-----+----------|
000010f0 2d 2d 2d 2b 0d 20 20 20 20 20 20 20 7c 20 26 46 |---+. | &F|
00001100 45 36 31 20 7c 20 44 61 74 61 20 72 65 67 69 73 |E61 | Data regis|
00001110 74 65 72 20 41 20 20 20 20 20 20 20 20 20 20 20 |ter A |
00001120 20 20 20 20 20 20 20 20 20 20 7c 20 44 52 41 20 | | DRA |
00001130 20 20 20 20 20 20 20 20 7c 0d 20 20 20 20 20 20 | |. |
00001140 20 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d | +-------+------|
00001150 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001160 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b |---------------+|
00001170 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 20 |-------------+. |
00001180 20 20 20 20 20 20 7c 20 26 46 45 36 30 20 7c 20 | | &FE60 | |
00001190 44 61 74 61 20 72 65 67 69 73 74 65 72 20 42 20 |Data register B |
000011a0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
000011b0 20 20 20 20 7c 20 44 52 42 20 20 20 20 20 20 20 | | DRB |
000011c0 20 20 7c 0d 20 20 20 20 20 20 20 2b 2d 2d 2d 2d | |. +----|
000011d0 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |---+------------|
000011e0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
000011f0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d |---------+------|
00001200 2d 2d 2d 2d 2d 2d 2d 2b 0d 0d 46 69 67 75 72 65 |-------+..Figure|
00001210 20 31 20 20 54 68 65 20 56 49 41 2d 42 20 72 65 | 1 The VIA-B re|
00001220 67 69 73 74 65 72 73 0d 2d 2d 2d 2d 2d 2d 2d 2d |gisters.--------|
00001230 20 20 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d | --------------|
00001240 2d 2d 2d 2d 2d 0d 0d 0d 46 69 76 65 20 6f 66 20 |-----...Five of |
00001250 74 68 65 73 65 20 31 36 20 72 65 67 69 73 74 65 |these 16 registe|
00001260 72 73 20 61 72 65 20 6f 66 20 69 6e 74 65 72 65 |rs are of intere|
00001270 73 74 20 77 68 65 6e 20 75 73 69 6e 67 20 61 20 |st when using a |
00001280 6d 6f 75 73 65 2e 20 54 68 65 79 0d 61 72 65 20 |mouse. They.are |
00001290 64 61 74 61 20 72 65 67 69 73 74 65 72 20 42 20 |data register B |
000012a0 28 44 52 42 2c 20 26 46 45 36 30 29 2c 20 64 61 |(DRB, &FE60), da|
000012b0 74 61 20 64 69 72 65 63 74 69 6f 6e 20 72 65 67 |ta direction reg|
000012c0 69 73 74 65 72 20 42 20 28 44 44 52 42 2c 20 26 |ister B (DDRB, &|
000012d0 46 45 36 32 29 2c 0d 74 68 65 20 70 65 72 69 70 |FE62),.the perip|
000012e0 68 65 72 61 6c 20 63 6f 6e 74 72 6f 6c 20 72 65 |heral control re|
000012f0 67 69 73 74 65 72 20 28 50 43 52 2c 20 26 46 45 |gister (PCR, &FE|
00001300 36 43 29 2c 20 74 68 65 20 69 6e 74 65 72 72 75 |6C), the interru|
00001310 70 74 20 66 6c 61 67 20 72 65 67 69 73 74 65 72 |pt flag register|
00001320 0d 28 49 46 52 2c 20 26 46 45 36 44 29 2c 20 61 |.(IFR, &FE6D), a|
00001330 6e 64 20 74 68 65 20 69 6e 74 65 72 72 75 70 74 |nd the interrupt|
00001340 20 65 6e 61 62 6c 65 20 72 65 67 69 73 74 65 72 | enable register|
00001350 20 28 49 45 52 2c 20 26 46 45 36 45 29 2e 20 54 | (IER, &FE6E). T|
00001360 68 65 0d 61 75 78 69 6c 6c 61 72 79 20 63 6f 6e |he.auxillary con|
00001370 74 72 6f 6c 20 72 65 67 69 73 74 65 72 20 28 41 |trol register (A|
00001380 43 52 2c 20 26 46 45 36 42 29 20 69 73 20 61 6c |CR, &FE6B) is al|
00001390 73 6f 20 6f 66 20 70 61 73 73 69 6e 67 20 69 6e |so of passing in|
000013a0 74 65 72 65 73 74 2e 0d 0d 42 6f 74 68 20 74 68 |terest...Both th|
000013b0 65 20 73 79 73 74 65 6d 20 56 49 41 20 61 6e 64 |e system VIA and|
000013c0 20 74 68 65 20 75 73 65 72 20 56 49 41 20 68 61 | the user VIA ha|
000013d0 76 65 20 32 30 20 49 2f 4f 20 6c 69 6e 65 73 20 |ve 20 I/O lines |
000013e0 67 72 6f 75 70 65 64 20 69 6e 74 6f 20 61 6e 20 |grouped into an |
000013f0 41 0d 73 69 64 65 20 61 6e 64 20 61 20 42 20 73 |A.side and a B s|
00001400 69 64 65 20 6f 66 20 31 30 20 6c 69 6e 65 73 20 |ide of 10 lines |
00001410 65 61 63 68 2e 20 54 68 65 73 65 20 31 30 20 6c |each. These 10 l|
00001420 69 6e 65 73 20 61 72 65 20 64 69 76 69 64 65 64 |ines are divided|
00001430 20 69 6e 74 6f 20 38 20 64 61 74 61 0d 6c 69 6e | into 8 data.lin|
00001440 65 73 20 61 6e 64 20 32 20 68 61 6e 64 73 68 61 |es and 2 handsha|
00001450 6b 65 20 6c 69 6e 65 73 2e 20 54 68 65 20 64 61 |ke lines. The da|
00001460 74 61 20 6c 69 6e 65 73 20 61 72 65 20 63 61 6c |ta lines are cal|
00001470 6c 65 64 20 50 41 30 20 74 6f 20 50 41 37 20 6f |led PA0 to PA7 o|
00001480 6e 20 74 68 65 20 41 0d 73 69 64 65 20 61 6e 64 |n the A.side and|
00001490 20 50 42 30 20 74 6f 20 50 42 37 20 6f 6e 20 74 | PB0 to PB7 on t|
000014a0 68 65 20 42 20 73 69 64 65 2e 20 44 61 74 61 20 |he B side. Data |
000014b0 6c 69 6e 65 73 20 50 41 30 20 74 6f 20 50 41 37 |lines PA0 to PA7|
000014c0 20 63 61 6e 20 62 65 20 72 65 61 64 20 66 72 6f | can be read fro|
000014d0 6d 0d 6f 72 20 77 72 69 74 74 65 6e 20 74 6f 20 |m.or written to |
000014e0 64 61 74 61 20 72 65 67 69 73 74 65 72 20 41 20 |data register A |
000014f0 28 26 46 45 36 31 29 20 61 6e 64 20 64 61 74 61 |(&FE61) and data|
00001500 20 6c 69 6e 65 73 20 50 42 30 20 74 6f 20 50 42 | lines PB0 to PB|
00001510 37 20 63 61 6e 20 62 65 0d 72 65 61 64 20 66 72 |7 can be.read fr|
00001520 6f 6d 20 6f 72 20 77 72 69 74 74 65 6e 20 74 6f |om or written to|
00001530 20 64 61 74 61 20 72 65 67 69 73 74 65 72 20 42 | data register B|
00001540 20 28 26 46 45 36 30 29 2e 20 54 68 65 20 42 20 | (&FE60). The B |
00001550 73 69 64 65 20 6f 66 20 56 49 41 2d 42 20 69 73 |side of VIA-B is|
00001560 0d 6b 6e 6f 77 6e 20 61 73 20 74 68 65 20 55 73 |.known as the Us|
00001570 65 72 20 50 6f 72 74 20 61 6e 64 20 50 42 30 20 |er Port and PB0 |
00001580 74 6f 20 50 42 37 20 61 72 65 20 74 68 65 20 55 |to PB7 are the U|
00001590 73 65 72 20 50 6f 72 74 20 64 61 74 61 20 6c 69 |ser Port data li|
000015a0 6e 65 73 2e 20 54 68 65 0d 68 61 6e 64 73 68 61 |nes. The.handsha|
000015b0 6b 65 20 6c 69 6e 65 73 20 61 72 65 20 63 61 6c |ke lines are cal|
000015c0 6c 65 64 20 43 41 31 20 61 6e 64 20 43 41 32 20 |led CA1 and CA2 |
000015d0 6f 6e 20 74 68 65 20 41 20 73 69 64 65 20 61 6e |on the A side an|
000015e0 64 20 43 42 31 20 61 6e 64 20 43 42 32 20 6f 6e |d CB1 and CB2 on|
000015f0 0d 74 68 65 20 42 20 73 69 64 65 2e 20 43 42 31 |.the B side. CB1|
00001600 20 61 6e 64 20 43 42 32 20 61 72 65 20 74 68 65 | and CB2 are the|
00001610 20 55 73 65 72 20 50 6f 72 74 20 68 61 6e 64 73 | User Port hands|
00001620 68 61 6b 65 20 6c 69 6e 65 73 2e 0d 0d 54 68 65 |hake lines...The|
00001630 20 55 73 65 72 20 50 6f 72 74 20 64 61 74 61 20 | User Port data |
00001640 72 65 67 69 73 74 65 72 2c 20 44 52 42 2c 20 63 |register, DRB, c|
00001650 61 6e 20 62 65 20 6d 61 64 65 20 61 6e 20 69 6e |an be made an in|
00001660 70 75 74 20 72 65 67 69 73 74 65 72 20 62 79 20 |put register by |
00001670 77 72 69 74 69 6e 67 0d 74 68 65 20 6e 75 6d 62 |writing.the numb|
00001680 65 72 20 7a 65 72 6f 20 69 6e 74 6f 20 44 44 52 |er zero into DDR|
00001690 42 2e 20 43 6c 65 61 72 69 6e 67 20 61 20 62 69 |B. Clearing a bi|
000016a0 74 20 69 6e 20 44 44 52 42 20 6d 61 6b 65 73 20 |t in DDRB makes |
000016b0 74 68 65 20 65 71 69 76 61 6c 65 6e 74 20 62 69 |the eqivalent bi|
000016c0 74 0d 69 6e 20 44 52 42 20 61 6e 20 69 6e 70 75 |t.in DRB an inpu|
000016d0 74 2e 20 53 65 74 74 69 6e 67 20 61 20 62 69 74 |t. Setting a bit|
000016e0 20 69 6e 20 44 44 52 42 20 6d 61 6b 65 73 20 74 | in DDRB makes t|
000016f0 68 65 20 65 71 75 69 76 61 6c 65 6e 74 20 62 69 |he equivalent bi|
00001700 74 20 69 6e 20 44 52 42 20 61 6e 0d 6f 75 74 70 |t in DRB an.outp|
00001710 75 74 2e 0d 0d 54 68 65 20 70 65 72 69 70 68 65 |ut...The periphe|
00001720 72 61 6c 20 63 6f 6e 74 72 6f 6c 20 72 65 67 69 |ral control regi|
00001730 73 74 65 72 20 69 73 20 75 73 65 64 20 74 6f 20 |ster is used to |
00001740 63 6f 6e 74 72 6f 6c 20 74 68 65 20 75 73 65 20 |control the use |
00001750 6f 66 20 74 68 65 0d 68 61 6e 64 73 68 61 6b 65 |of the.handshake|
00001760 20 6c 69 6e 65 73 2e 20 54 68 65 20 56 49 41 2d | lines. The VIA-|
00001770 42 20 50 43 52 20 61 6e 64 20 74 68 65 20 69 6e |B PCR and the in|
00001780 74 65 72 70 72 65 74 61 74 69 6f 6e 20 6f 66 20 |terpretation of |
00001790 69 74 73 20 62 69 74 73 20 69 73 20 73 68 6f 77 |its bits is show|
000017a0 6e 0d 69 6e 20 66 69 67 75 72 65 20 32 2e 0d 0d |n.in figure 2...|
000017b0 0d 0d 62 69 74 20 37 20 20 20 20 20 20 20 36 20 |..bit 7 6 |
000017c0 20 20 20 20 20 20 35 20 20 20 20 20 20 20 20 20 | 5 |
000017d0 34 20 20 20 20 20 20 20 20 20 33 20 20 20 20 20 |4 3 |
000017e0 20 20 32 20 20 20 20 20 20 20 31 20 20 20 20 20 | 2 1 |
000017f0 20 20 20 20 30 0d 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d | 0.+-------+-|
00001800 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d |------+-------+-|
00001810 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d |----------+-----|
00001820 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d |--+-------+-----|
00001830 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d |--+-----------+.|
00001840 7c 20 20 20 20 20 20 43 42 32 20 63 6f 6e 74 72 || CB2 contr|
00001850 6f 6c 20 20 20 20 20 20 7c 43 42 31 20 63 6f 6e |ol |CB1 con|
00001860 74 72 6f 6c 7c 20 20 20 20 20 20 43 41 32 20 43 |trol| CA2 C|
00001870 6f 6e 74 72 6f 6c 20 20 20 20 20 20 7c 43 41 31 |ontrol |CA1|
00001880 20 63 6f 6e 74 72 6f 6c 7c 0d 7c 20 20 20 20 20 | control|.| |
00001890 20 20 55 73 65 72 20 50 6f 72 74 20 20 20 20 20 | User Port |
000018a0 20 20 7c 20 55 73 65 72 20 50 6f 72 74 20 7c 20 | | User Port | |
000018b0 20 20 20 50 72 69 6e 74 65 72 20 73 74 72 6f 62 | Printer strob|
000018c0 65 20 20 20 20 20 7c 50 72 69 6e 74 65 72 20 61 |e |Printer a|
000018d0 63 6b 7c 0d 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d |ck|.+-------+---|
000018e0 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d |----+-------+---|
000018f0 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d |--------+-------|
00001900 2b 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d |+-------+-------|
00001910 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 0d 0d |+-----------+...|
00001920 20 42 69 74 20 20 49 6e 74 65 72 70 72 65 74 61 | Bit Interpreta|
00001930 74 69 6f 6e 20 69 66 20 62 69 74 20 63 6c 65 61 |tion if bit clea|
00001940 72 20 28 30 29 20 20 20 49 6e 74 65 72 70 72 65 |r (0) Interpre|
00001950 74 61 74 69 6f 6e 20 69 66 20 62 69 74 20 73 65 |tation if bit se|
00001960 74 20 28 31 29 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d 2d |t (1).+---+-----|
00001970 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001980 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d |------------+---|
00001990 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
000019a0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d |--------------+.|
000019b0 7c 20 30 20 7c 53 65 74 20 62 69 74 20 31 20 6f || 0 |Set bit 1 o|
000019c0 66 20 49 46 52 20 6f 6e 20 2d 76 65 20 67 6f 69 |f IFR on -ve goi|
000019d0 6e 67 20 43 41 31 7c 53 65 74 20 62 69 74 20 31 |ng CA1|Set bit 1|
000019e0 20 6f 66 20 49 46 52 20 6f 6e 20 2b 76 65 20 67 | of IFR on +ve g|
000019f0 6f 69 6e 67 20 43 41 31 7c 0d 2b 2d 2d 2d 2b 2d |oing CA1|.+---+-|
00001a00 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00001a20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |+---------------|
00001a30 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001a40 2d 2d 2b 0d 7c 20 31 20 7c 20 44 52 41 20 73 65 |--+.| 1 | DRA se|
00001a50 6c 65 63 74 65 64 20 74 6f 20 63 6c 65 61 72 20 |lected to clear |
00001a60 69 6e 74 65 72 72 75 70 74 20 7c 20 49 6e 74 65 |interrupt | Inte|
00001a70 72 72 75 70 74 20 6e 6f 74 20 63 6c 65 61 72 65 |rrupt not cleare|
00001a80 64 20 62 79 20 44 52 41 20 20 20 20 7c 0d 2b 2d |d by DRA |.+-|
00001a90 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |--+-------------|
00001aa0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001ab0 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----+-----------|
00001ac0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001ad0 2d 2d 2d 2d 2d 2d 2b 0d 7c 20 32 20 7c 53 65 74 |------+.| 2 |Set|
00001ae0 20 62 69 74 20 30 20 6f 66 20 49 46 52 20 6f 6e | bit 0 of IFR on|
00001af0 20 2d 76 65 20 67 6f 69 6e 67 20 43 41 32 7c 53 | -ve going CA2|S|
00001b00 65 74 20 62 69 74 20 30 20 6f 66 20 49 46 52 20 |et bit 0 of IFR |
00001b10 6f 6e 20 2b 76 65 20 67 6f 69 6e 67 20 43 41 32 |on +ve going CA2|
00001b20 7c 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d ||.+---+---------|
00001b30 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001b40 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d |--------+-------|
00001b50 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001b60 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 7c 20 33 20 |----------+.| 3 |
00001b70 7c 20 42 69 74 20 33 20 61 6c 77 61 79 73 20 73 || Bit 3 always s|
00001b80 65 74 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |et |
00001b90 20 20 7c 20 53 65 74 20 43 41 32 20 74 6f 20 6f | | Set CA2 to o|
00001ba0 75 74 70 75 74 20 28 61 6c 77 61 79 73 20 73 65 |utput (always se|
00001bb0 74 29 20 20 7c 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d 2d |t) |.+---+-----|
00001bc0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001bd0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d |------------+---|
00001be0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001bf0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d |--------------+.|
00001c00 7c 20 34 20 7c 53 65 74 20 62 69 74 20 34 20 6f || 4 |Set bit 4 o|
00001c10 66 20 49 46 52 20 6f 6e 20 2d 76 65 20 67 6f 69 |f IFR on -ve goi|
00001c20 6e 67 20 43 42 31 7c 53 65 74 20 62 69 74 20 34 |ng CB1|Set bit 4|
00001c30 20 6f 66 20 49 46 52 20 6f 6e 20 2b 76 65 20 67 | of IFR on +ve g|
00001c40 6f 69 6e 67 20 43 42 31 7c 0d 2b 2d 2d 2d 2b 2d |oing CB1|.+---+-|
00001c50 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00001c70 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |+---------------|
00001c80 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001c90 2d 2d 2b 0d 7c 20 35 20 7c 20 44 52 42 20 73 65 |--+.| 5 | DRB se|
00001ca0 6c 65 63 74 65 64 20 74 6f 20 63 6c 65 61 72 20 |lected to clear |
00001cb0 69 6e 74 65 72 72 75 70 74 20 7c 20 49 6e 74 65 |interrupt | Inte|
00001cc0 72 72 75 70 74 20 6e 6f 74 20 63 6c 65 61 72 65 |rrupt not cleare|
00001cd0 64 20 62 79 20 44 52 42 20 20 20 20 7c 0d 2b 2d |d by DRB |.+-|
00001ce0 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |--+-------------|
00001cf0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001d00 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----+-----------|
00001d10 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001d20 2d 2d 2d 2d 2d 2d 2b 0d 7c 20 36 20 7c 53 65 74 |------+.| 6 |Set|
00001d30 20 62 69 74 20 33 20 6f 66 20 49 46 52 20 6f 6e | bit 3 of IFR on|
00001d40 20 2d 76 65 20 67 6f 69 6e 67 20 43 42 32 7c 53 | -ve going CB2|S|
00001d50 65 74 20 62 69 74 20 33 20 6f 66 20 49 46 52 20 |et bit 3 of IFR |
00001d60 6f 6e 20 2b 76 65 20 67 6f 69 6e 67 20 43 42 32 |on +ve going CB2|
00001d70 7c 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d ||.+---+---------|
00001d80 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001d90 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d |--------+-------|
00001da0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001db0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 7c 20 37 20 |----------+.| 7 |
00001dc0 7c 20 53 65 74 20 43 42 32 20 74 6f 20 69 6e 70 || Set CB2 to inp|
00001dd0 75 74 20 6d 6f 64 65 20 20 20 20 20 20 20 20 20 |ut mode |
00001de0 20 20 7c 20 53 65 74 20 43 42 32 20 74 6f 20 6f | | Set CB2 to o|
00001df0 75 74 70 75 74 20 6d 6f 64 65 20 20 20 20 20 20 |utput mode |
00001e00 20 20 20 20 7c 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d 2d | |.+---+-----|
00001e10 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001e20 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d |------------+---|
00001e30 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001e40 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d |--------------+.|
00001e50 0d 46 69 67 75 72 65 20 32 20 20 54 68 65 20 70 |.Figure 2 The p|
00001e60 65 72 69 70 68 65 72 61 6c 20 63 6f 6e 74 72 6f |eripheral contro|
00001e70 6c 20 72 65 67 69 73 74 65 72 0d 2d 2d 2d 2d 2d |l register.-----|
00001e80 2d 2d 2d 20 20 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |--- -----------|
00001e90 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00001ea0 2d 2d 2d 2d 0d 0d 0d 42 6f 74 68 20 43 42 31 20 |----...Both CB1 |
00001eb0 61 6e 64 20 43 42 32 20 61 72 65 20 75 73 65 64 |and CB2 are used|
00001ec0 20 61 73 20 69 6e 70 75 74 73 20 62 79 20 61 6e | as inputs by an|
00001ed0 20 41 4d 58 20 63 6f 6d 70 61 74 69 62 6c 65 20 | AMX compatible |
00001ee0 6d 6f 75 73 65 2e 20 57 68 65 6e 20 75 73 69 6e |mouse. When usin|
00001ef0 67 0d 69 6e 74 65 72 72 75 70 74 20 64 72 69 76 |g.interrupt driv|
00001f00 65 6e 20 6d 6f 75 73 65 20 73 6f 66 74 77 61 72 |en mouse softwar|
00001f10 65 20 79 6f 75 20 77 69 6c 6c 20 6e 65 65 64 20 |e you will need |
00001f20 74 6f 20 73 65 74 20 62 69 74 73 20 34 20 61 6e |to set bits 4 an|
00001f30 64 20 36 20 61 6e 64 0d 63 6c 65 61 72 20 62 69 |d 6 and.clear bi|
00001f40 74 73 20 35 20 61 6e 64 20 37 20 6f 66 20 74 68 |ts 5 and 7 of th|
00001f50 65 20 50 43 52 2e 20 54 68 69 73 20 6d 65 61 6e |e PCR. This mean|
00001f60 73 20 74 68 61 74 20 61 20 70 6f 73 69 74 69 76 |s that a positiv|
00001f70 65 20 67 6f 69 6e 67 20 73 69 67 6e 61 6c 20 6f |e going signal o|
00001f80 6e 0d 65 69 74 68 65 72 20 43 42 31 20 6f 72 20 |n.either CB1 or |
00001f90 43 42 32 20 77 69 6c 6c 20 67 65 6e 65 72 61 74 |CB2 will generat|
00001fa0 65 20 61 6e 20 49 51 52 20 69 6e 74 65 72 72 75 |e an IQR interru|
00001fb0 70 74 20 61 6e 64 20 74 68 61 74 20 69 6e 74 65 |pt and that inte|
00001fc0 72 72 75 70 74 20 77 69 6c 6c 0d 62 65 20 63 6c |rrupt will.be cl|
00001fd0 65 61 72 65 64 20 62 79 20 72 65 61 64 69 6e 67 |eared by reading|
00001fe0 20 64 61 74 61 20 72 65 67 69 73 74 65 72 20 42 | data register B|
00001ff0 2c 20 69 65 2e 20 62 79 20 72 65 61 64 69 6e 67 |, ie. by reading|
00002000 20 74 68 65 20 64 61 74 61 20 6c 69 6e 65 73 2e | the data lines.|
00002010 20 42 69 74 0d 37 20 6f 66 20 74 68 65 20 50 43 | Bit.7 of the PC|
00002020 52 20 69 73 20 63 6c 65 61 72 20 74 6f 20 6d 61 |R is clear to ma|
00002030 6b 65 20 43 42 32 20 61 6e 20 69 6e 70 75 74 2c |ke CB2 an input,|
00002040 20 43 42 31 20 69 73 20 61 6e 20 69 6e 70 75 74 | CB1 is an input|
00002050 20 6c 69 6e 65 20 62 79 0d 64 65 66 61 75 6c 74 | line by.default|
00002060 2e 20 41 20 70 72 6f 67 72 61 6d 20 77 68 69 63 |. A program whic|
00002070 68 20 61 6c 74 65 72 73 20 62 69 74 73 20 34 20 |h alters bits 4 |
00002080 74 6f 20 37 20 6f 66 20 74 68 65 20 50 43 52 20 |to 7 of the PCR |
00002090 6d 75 73 74 20 6e 6f 74 20 61 6c 74 65 72 20 62 |must not alter b|
000020a0 69 74 73 0d 30 20 74 6f 20 33 20 77 68 69 63 68 |its.0 to 3 which|
000020b0 20 61 72 65 20 75 73 65 64 20 62 79 20 74 68 65 | are used by the|
000020c0 20 70 61 72 61 6c 6c 65 6c 20 70 72 69 6e 74 65 | parallel printe|
000020d0 72 20 69 6e 74 65 72 66 61 63 65 2e 20 54 68 65 |r interface. The|
000020e0 20 66 6f 6c 6c 6f 77 69 6e 67 0d 63 6f 64 65 20 | following.code |
000020f0 63 61 6e 20 62 65 20 75 73 65 64 20 74 6f 20 73 |can be used to s|
00002100 65 74 20 62 69 74 73 20 34 20 61 6e 64 20 36 20 |et bits 4 and 6 |
00002110 61 6e 64 20 63 6c 65 61 72 20 62 69 74 73 20 35 |and clear bits 5|
00002120 20 61 6e 64 20 37 20 6f 66 20 74 68 65 20 50 43 | and 7 of the PC|
00002130 52 3a 0d 0d 0d 20 20 4c 44 41 20 26 46 45 36 43 |R:... LDA &FE6C|
00002140 20 20 5c 20 6c 6f 61 64 20 41 20 77 69 74 68 20 | \ load A with |
00002150 74 68 65 20 63 6f 6e 74 65 6e 74 73 20 6f 66 20 |the contents of |
00002160 74 68 65 20 70 65 72 69 70 68 65 72 61 6c 20 63 |the peripheral c|
00002170 6f 6e 74 72 6f 6c 20 72 65 67 69 73 74 65 72 0d |ontrol register.|
00002180 20 20 41 4e 44 20 23 26 30 46 20 20 20 5c 20 41 | AND #&0F \ A|
00002190 4e 44 20 77 69 74 68 20 25 30 30 30 30 31 31 31 |ND with %0000111|
000021a0 31 2c 20 69 65 2e 20 63 6c 65 61 72 20 62 69 74 |1, ie. clear bit|
000021b0 20 34 2d 37 0d 20 20 4f 52 41 20 23 26 35 30 20 | 4-7. ORA #&50 |
000021c0 20 20 5c 20 4f 52 20 77 69 74 68 20 25 30 31 30 | \ OR with %010|
000021d0 31 30 30 30 30 2c 20 69 65 2e 20 73 65 74 20 62 |10000, ie. set b|
000021e0 69 74 73 20 34 20 61 6e 64 20 36 0d 20 20 53 54 |its 4 and 6. ST|
000021f0 41 20 26 46 45 36 43 20 20 5c 20 73 74 6f 72 65 |A &FE6C \ store|
00002200 20 41 20 69 6e 20 74 68 65 20 70 65 72 69 70 68 | A in the periph|
00002210 65 72 61 6c 20 63 6f 6e 74 72 6f 6c 20 72 65 67 |eral control reg|
00002220 69 73 74 65 72 0d 0d 0d 4d 6f 75 73 65 20 67 65 |ister...Mouse ge|
00002230 6e 65 72 61 74 65 64 20 69 6e 74 65 72 72 75 70 |nerated interrup|
00002240 74 73 20 61 72 65 20 65 6e 61 62 6c 65 64 20 62 |ts are enabled b|
00002250 79 20 73 65 74 74 69 6e 67 20 62 69 74 73 20 33 |y setting bits 3|
00002260 20 61 6e 64 20 34 20 6f 66 20 74 68 65 0d 69 6e | and 4 of the.in|
00002270 74 65 72 72 75 70 74 20 65 6e 61 62 6c 65 20 72 |terrupt enable r|
00002280 65 67 69 73 74 65 72 2e 20 53 65 74 74 69 6e 67 |egister. Setting|
00002290 20 74 68 65 73 65 20 62 69 74 73 20 75 73 65 73 | these bits uses|
000022a0 20 61 6e 20 6f 64 64 20 6d 65 74 68 6f 64 2e 20 | an odd method. |
000022b0 54 6f 20 61 6c 74 65 72 0d 61 20 62 69 74 20 69 |To alter.a bit i|
000022c0 6e 20 74 68 65 20 49 45 52 20 79 6f 75 20 6d 75 |n the IER you mu|
000022d0 73 74 20 77 72 69 74 65 20 61 20 6e 75 6d 62 65 |st write a numbe|
000022e0 72 20 74 6f 20 74 68 65 20 49 45 52 20 77 69 74 |r to the IER wit|
000022f0 68 20 61 20 31 20 69 6e 20 74 68 65 20 73 61 6d |h a 1 in the sam|
00002300 65 0d 62 69 74 20 70 6f 73 69 74 69 6f 6e 2e 20 |e.bit position. |
00002310 49 66 20 62 69 74 20 37 20 6f 66 20 74 68 65 20 |If bit 7 of the |
00002320 6e 75 6d 62 65 72 20 69 73 20 73 65 74 20 74 68 |number is set th|
00002330 65 6e 20 74 68 65 20 73 65 6c 65 63 74 65 64 20 |en the selected |
00002340 62 69 74 20 28 6f 72 0d 62 69 74 73 29 20 77 69 |bit (or.bits) wi|
00002350 6c 6c 20 61 6c 73 6f 20 62 65 20 73 65 74 20 74 |ll also be set t|
00002360 6f 20 31 2e 20 49 66 20 62 69 74 20 37 20 6f 66 |o 1. If bit 7 of|
00002370 20 74 68 65 20 6e 75 6d 62 65 72 20 69 73 20 63 | the number is c|
00002380 6c 65 61 72 20 74 68 65 6e 20 74 68 65 0d 73 65 |lear then the.se|
00002390 6c 65 63 74 65 64 20 62 69 74 20 28 6f 72 20 62 |lected bit (or b|
000023a0 69 74 73 29 20 77 69 6c 6c 20 62 65 20 63 6c 65 |its) will be cle|
000023b0 61 72 65 64 2e 20 54 68 65 20 73 65 6c 65 63 74 |ared. The select|
000023c0 65 64 20 62 69 74 73 20 28 30 20 74 6f 20 36 29 |ed bits (0 to 6)|
000023d0 20 61 72 65 20 73 65 74 0d 74 6f 20 74 68 65 20 | are set.to the |
000023e0 73 61 6d 65 20 73 74 61 74 65 20 61 73 20 62 69 |same state as bi|
000023f0 74 20 37 2e 20 54 6f 20 73 65 74 20 62 69 74 73 |t 7. To set bits|
00002400 20 33 20 61 6e 64 20 34 20 6f 66 20 74 68 65 20 | 3 and 4 of the |
00002410 49 45 52 20 79 6f 75 20 68 61 76 65 20 74 6f 0d |IER you have to.|
00002420 77 72 69 74 65 20 74 68 65 20 6e 75 6d 62 65 72 |write the number|
00002430 20 26 39 38 20 28 25 31 30 30 31 31 30 30 30 29 | &98 (%10011000)|
00002440 20 69 6e 74 6f 20 74 68 65 20 49 45 52 2e 20 42 | into the IER. B|
00002450 69 74 73 20 33 20 61 6e 64 20 34 20 77 69 6c 6c |its 3 and 4 will|
00002460 20 74 68 65 6e 20 74 61 6b 65 0d 74 68 65 20 76 | then take.the v|
00002470 61 6c 75 65 20 6f 66 20 62 69 74 20 37 20 61 6e |alue of bit 7 an|
00002480 64 20 77 69 6c 6c 20 62 65 20 73 65 74 2c 20 65 |d will be set, e|
00002490 6e 61 62 6c 69 6e 67 20 69 6e 74 65 72 72 75 70 |nabling interrup|
000024a0 74 73 20 66 72 6f 6d 20 43 42 31 20 61 6e 64 20 |ts from CB1 and |
000024b0 43 42 32 2e 0d 0d 57 68 65 6e 20 62 69 74 73 20 |CB2...When bits |
000024c0 33 20 61 6e 64 20 34 20 6f 66 20 74 68 65 20 49 |3 and 4 of the I|
000024d0 45 52 20 61 72 65 20 73 65 74 20 74 68 65 6e 20 |ER are set then |
000024e0 61 20 70 6f 73 69 74 69 76 65 20 74 72 61 6e 73 |a positive trans|
000024f0 69 74 69 6f 6e 20 6f 6e 20 43 42 31 0d 77 69 6c |ition on CB1.wil|
00002500 6c 20 73 65 74 20 62 69 74 20 34 20 6f 66 20 74 |l set bit 4 of t|
00002510 68 65 20 69 6e 74 65 72 72 75 70 74 20 66 6c 61 |he interrupt fla|
00002520 67 20 72 65 67 69 73 74 65 72 20 61 6e 64 20 67 |g register and g|
00002530 65 6e 65 72 61 74 65 20 61 6e 20 49 52 51 0d 69 |enerate an IRQ.i|
00002540 6e 74 65 72 72 75 70 74 2e 20 41 20 70 6f 73 69 |nterrupt. A posi|
00002550 74 69 76 65 20 74 72 61 6e 73 69 74 69 6f 6e 20 |tive transition |
00002560 6f 6e 20 43 42 32 20 77 69 6c 6c 20 73 65 74 20 |on CB2 will set |
00002570 62 69 74 20 33 20 6f 66 20 74 68 65 20 49 46 52 |bit 3 of the IFR|
00002580 20 61 6e 64 0d 67 65 6e 65 72 61 74 65 20 61 6e | and.generate an|
00002590 20 49 51 52 20 69 6e 74 65 72 72 75 70 74 2e 20 | IQR interrupt. |
000025a0 54 68 65 73 65 20 69 6e 74 65 72 72 75 70 74 73 |These interrupts|
000025b0 20 63 61 6e 20 62 65 20 72 65 63 6f 67 6e 69 73 | can be recognis|
000025c0 65 64 20 62 65 63 61 75 73 65 0d 65 69 74 68 65 |ed because.eithe|
000025d0 72 20 62 69 74 73 20 37 20 61 6e 64 20 33 20 6f |r bits 7 and 3 o|
000025e0 66 20 49 46 52 20 6f 72 20 62 69 74 73 20 37 20 |f IFR or bits 7 |
000025f0 61 6e 64 20 34 20 6f 66 20 74 68 65 20 49 46 52 |and 4 of the IFR|
00002600 20 77 69 6c 6c 20 62 65 20 73 65 74 2e 0d 0d 4d | will be set...M|
00002610 6f 75 73 65 20 67 65 6e 65 72 61 74 65 64 20 69 |ouse generated i|
00002620 6e 74 65 72 72 75 70 74 73 20 61 72 65 20 64 69 |nterrupts are di|
00002630 73 61 62 6c 65 64 20 62 79 20 77 72 69 74 69 6e |sabled by writin|
00002640 67 20 74 68 65 20 6e 75 6d 62 65 72 20 26 30 38 |g the number &08|
00002650 0d 28 25 30 30 30 31 31 30 30 30 29 20 69 6e 74 |.(%00011000) int|
00002660 6f 20 74 68 65 20 49 45 52 2e 20 54 68 69 73 20 |o the IER. This |
00002670 63 6c 65 61 72 73 20 62 69 74 73 20 33 20 61 6e |clears bits 3 an|
00002680 64 20 34 20 6f 66 20 74 68 65 20 49 45 52 20 73 |d 4 of the IER s|
00002690 6f 20 74 68 61 74 20 61 0d 70 6f 73 69 74 69 76 |o that a.positiv|
000026a0 65 20 67 6f 69 6e 67 20 74 72 61 6e 73 69 74 69 |e going transiti|
000026b0 6f 6e 20 6f 6e 20 43 42 31 20 6f 72 20 43 42 32 |on on CB1 or CB2|
000026c0 20 77 69 6c 6c 20 73 74 69 6c 6c 20 73 65 74 20 | will still set |
000026d0 65 69 74 68 65 72 20 62 69 74 20 34 20 6f 72 20 |either bit 4 or |
000026e0 62 69 74 0d 33 20 6f 66 20 74 68 65 20 49 46 52 |bit.3 of the IFR|
000026f0 20 62 75 74 20 69 74 20 77 69 6c 6c 20 6e 6f 74 | but it will not|
00002700 20 67 65 6e 65 72 61 74 65 20 61 6e 20 49 52 51 | generate an IRQ|
00002710 20 69 6e 74 65 72 72 75 70 74 2e 20 4d 6f 75 73 | interrupt. Mous|
00002720 65 20 67 65 6e 65 72 61 74 65 64 0d 69 6e 74 65 |e generated.inte|
00002730 72 72 75 70 74 73 20 63 61 6e 20 62 65 20 65 6e |rrupts can be en|
00002740 61 62 6c 65 64 20 77 69 74 68 20 3f 26 46 45 36 |abled with ?&FE6|
00002750 45 3d 26 39 38 20 6f 72 20 2a 46 58 20 31 35 31 |E=&98 or *FX 151|
00002760 2c 37 38 2c 31 35 32 20 61 6e 64 20 64 69 73 61 |,78,152 and disa|
00002770 62 6c 65 64 0d 77 69 74 68 20 3f 26 46 45 36 45 |bled.with ?&FE6E|
00002780 3d 26 31 38 20 6f 72 20 2a 46 58 20 31 35 31 2c |=&18 or *FX 151,|
00002790 37 38 2c 32 34 0d 0d 54 68 65 20 69 6e 74 65 72 |78,24..The inter|
000027a0 72 75 70 74 20 65 6e 61 62 6c 65 20 72 65 67 69 |rupt enable regi|
000027b0 73 74 65 72 20 61 6e 64 20 74 68 65 20 69 6e 74 |ster and the int|
000027c0 65 72 72 75 70 74 20 66 6c 61 67 20 72 65 67 69 |errupt flag regi|
000027d0 73 74 65 72 20 77 6f 72 6b 20 61 73 20 61 0d 70 |ster work as a.p|
000027e0 61 69 72 20 61 6e 64 20 74 68 65 20 66 6c 61 67 |air and the flag|
000027f0 20 72 65 67 69 73 74 65 72 20 6d 75 73 74 20 62 | register must b|
00002800 65 20 69 6e 74 65 72 72 6f 67 61 74 65 64 20 62 |e interrogated b|
00002810 79 20 61 20 70 72 6f 67 72 61 6d 20 74 6f 20 73 |y a program to s|
00002820 65 65 20 69 66 20 61 0d 6d 6f 75 73 65 20 63 6f |ee if a.mouse co|
00002830 6e 6e 65 63 74 65 64 20 74 6f 20 74 68 65 20 55 |nnected to the U|
00002840 73 65 72 20 50 6f 72 74 20 69 73 20 74 68 65 20 |ser Port is the |
00002850 73 6f 75 72 63 65 20 6f 66 20 61 6e 20 69 6e 74 |source of an int|
00002860 65 72 72 75 70 74 2e 20 54 68 65 0d 69 6e 74 65 |errupt. The.inte|
00002870 72 70 72 65 74 61 74 69 6f 6e 20 6f 66 20 74 68 |rpretation of th|
00002880 65 20 62 69 74 73 20 69 6e 20 74 68 65 20 49 46 |e bits in the IF|
00002890 52 20 69 73 20 74 61 62 75 6c 61 74 65 64 20 69 |R is tabulated i|
000028a0 6e 20 66 69 67 75 72 65 20 33 20 77 68 69 63 68 |n figure 3 which|
000028b0 20 73 68 6f 77 73 0d 74 68 61 74 20 62 69 74 73 | shows.that bits|
000028c0 20 37 20 61 6e 64 20 33 20 6f 72 20 37 20 61 6e | 7 and 3 or 7 an|
000028d0 64 20 34 20 6f 66 20 74 68 65 20 49 46 52 20 77 |d 4 of the IFR w|
000028e0 69 6c 6c 20 62 65 20 73 65 74 20 69 66 20 61 20 |ill be set if a |
000028f0 6d 6f 75 73 65 20 63 6f 6e 6e 65 63 74 65 64 0d |mouse connected.|
00002900 74 6f 20 74 68 65 20 55 73 65 72 20 50 6f 72 74 |to the User Port|
00002910 20 69 73 20 74 68 65 20 73 6f 75 72 63 65 20 6f | is the source o|
00002920 66 20 61 6e 20 69 6e 74 65 72 72 75 70 74 2e 0d |f an interrupt..|
00002930 0d 0d 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 |... |
00002940 37 20 20 20 20 20 20 20 36 20 20 20 20 20 35 20 |7 6 5 |
00002950 20 20 20 20 34 20 20 20 20 20 33 20 20 20 20 20 | 4 3 |
00002960 32 20 20 20 20 20 31 20 20 20 20 20 30 0d 20 20 |2 1 0. |
00002970 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d | +---------|
00002980 2b 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2b 2d 2d 2d |+-----+-----+---|
00002990 2d 2d 2b 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2b 2d |--+-----+-----+-|
000029a0 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2b 0d 20 20 26 46 |----+-----+. &F|
000029b0 45 36 45 20 7c 53 65 74 2f 43 6c 65 61 72 7c 20 |E6E |Set/Clear| |
000029c0 54 31 20 20 7c 20 54 32 20 20 7c 20 43 42 31 20 |T1 | T2 | CB1 |
000029d0 7c 20 43 42 32 20 7c 20 53 52 20 20 7c 20 43 41 || CB2 | SR | CA|
000029e0 31 20 7c 20 43 41 32 20 7c 20 49 45 52 0d 20 20 |1 | CA2 | IER. |
000029f0 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d | +---------|
00002a00 2b 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2b 2d 2d 2d |+-----+-----+---|
00002a10 2d 2d 2b 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2b 2d |--+-----+-----+-|
00002a20 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2b 0d 20 20 26 46 |----+-----+. &F|
00002a30 45 36 44 20 7c 20 20 20 49 52 51 20 20 20 7c 20 |E6D | IRQ | |
00002a40 54 31 20 20 7c 20 54 32 20 20 7c 20 43 42 31 20 |T1 | T2 | CB1 |
00002a50 7c 20 43 42 32 20 7c 20 53 52 20 20 7c 20 43 41 || CB2 | SR | CA|
00002a60 31 20 7c 20 43 41 32 20 7c 20 49 46 52 0d 20 20 |1 | CA2 | IFR. |
00002a70 20 20 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d | +---------|
00002a80 2b 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2b 2d 2d 2d |+-----+-----+---|
00002a90 2d 2d 2b 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2b 2d |--+-----+-----+-|
00002aa0 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2b 0d 0d 0d 0d 20 |----+-----+.... |
00002ab0 42 69 74 20 20 20 43 61 75 73 65 20 6f 66 20 69 |Bit Cause of i|
00002ac0 6e 74 65 72 72 75 70 74 20 20 20 20 20 20 20 20 |nterrupt |
00002ad0 49 6e 74 65 72 70 72 65 74 61 74 69 6f 6e 0d 2b |Interpretation.+|
00002ae0 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |---+------------|
00002af0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d |-------------+--|
00002b00 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00002b20 2d 2d 2d 2d 2d 2d 2d 2b 0d 7c 20 30 20 7c 20 43 |-------+.| 0 | C|
00002b30 68 61 6e 67 65 20 6f 66 20 73 69 67 6e 61 6c 20 |hange of signal |
00002b40 6f 6e 20 43 41 32 20 7c 20 50 72 69 6e 74 65 72 |on CA2 | Printer|
00002b50 20 73 74 72 6f 62 65 20 20 20 20 20 20 20 20 20 | strobe |
00002b60 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
00002b70 20 7c 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d | |.+---+--------|
00002b80 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002b90 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |-+--------------|
00002ba0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002bb0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 7c 20 31 |-----------+.| 1|
00002bc0 20 7c 20 43 68 61 6e 67 65 20 6f 66 20 73 69 67 | | Change of sig|
00002bd0 6e 61 6c 20 6f 6e 20 43 41 31 20 7c 20 50 72 69 |nal on CA1 | Pri|
00002be0 6e 74 65 72 20 61 63 6b 6e 6f 77 6c 65 64 67 65 |nter acknowledge|
00002bf0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
00002c00 20 20 20 20 20 7c 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d | |.+---+----|
00002c10 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002c20 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |-----+----------|
00002c30 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002c40 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b |---------------+|
00002c50 0d 7c 20 32 20 7c 20 43 6f 6d 70 6c 65 74 69 6f |.| 2 | Completio|
00002c60 6e 20 6f 66 20 38 20 73 68 69 66 74 73 20 20 7c |n of 8 shifts ||
00002c70 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
*
00002c90 20 20 20 20 20 20 20 20 20 7c 0d 7c 20 20 20 7c | |.| ||
00002ca0 20 69 6e 20 74 68 65 20 73 68 69 66 74 20 72 65 | in the shift re|
00002cb0 67 69 73 74 65 72 20 20 20 7c 20 20 20 20 20 20 |gister | |
00002cc0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
*
00002ce0 20 20 20 7c 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d | |.+---+------|
00002cf0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002d00 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |---+------------|
00002d10 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002d20 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 7c |-------------+.||
00002d30 20 33 20 7c 20 43 68 61 6e 67 65 20 6f 66 20 73 | 3 | Change of s|
00002d40 69 67 6e 61 6c 20 6f 6e 20 43 42 32 20 7c 20 4d |ignal on CB2 | M|
00002d50 6f 75 73 65 20 6d 6f 76 65 6d 65 6e 74 20 69 6e |ouse movement in|
00002d60 20 74 68 65 20 59 20 64 69 72 65 63 74 69 6f 6e | the Y direction|
00002d70 20 20 20 20 20 20 20 7c 0d 2b 2d 2d 2d 2b 2d 2d | |.+---+--|
00002d80 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002d90 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d |-------+--------|
00002da0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00002dc0 2d 2b 0d 7c 20 34 20 7c 20 43 68 61 6e 67 65 20 |-+.| 4 | Change |
00002dd0 6f 66 20 73 69 67 6e 61 6c 20 6f 6e 20 43 42 31 |of signal on CB1|
00002de0 20 7c 20 4d 6f 75 73 65 20 6d 6f 76 65 6d 65 6e | | Mouse movemen|
00002df0 74 20 69 6e 20 74 68 65 20 58 20 64 69 72 65 63 |t in the X direc|
00002e00 74 69 6f 6e 20 20 20 20 20 20 20 7c 0d 2b 2d 2d |tion |.+--|
00002e10 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |-+--------------|
00002e20 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d |-----------+----|
00002e30 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00002e50 2d 2d 2d 2d 2d 2b 0d 7c 20 35 20 7c 20 54 69 6d |-----+.| 5 | Tim|
00002e60 65 72 20 32 20 63 6f 6d 70 6c 65 74 65 20 20 20 |er 2 complete |
00002e70 20 20 20 20 20 7c 20 20 20 20 20 20 20 20 20 20 | | |
00002e80 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
00002e90 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 7c | ||
00002ea0 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |.+---+----------|
00002eb0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b |---------------+|
00002ec0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00002ee0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 7c 20 36 20 7c |---------+.| 6 ||
00002ef0 20 54 69 6d 65 72 20 31 20 63 6f 6d 70 6c 65 74 | Timer 1 complet|
00002f00 65 20 20 20 20 20 20 20 20 7c 20 20 20 20 20 20 |e | |
00002f10 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |
*
00002f30 20 20 20 7c 0d 2b 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d | |.+---+------|
00002f40 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002f50 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |---+------------|
00002f60 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002f70 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d 7c |-------------+.||
00002f80 20 37 20 7c 20 41 6e 79 20 62 69 74 2c 20 30 20 | 7 | Any bit, 0 |
00002f90 74 6f 20 36 2c 20 69 73 20 73 65 74 20 7c 20 4f |to 6, is set | O|
00002fa0 6e 65 20 6f 66 20 74 68 65 20 61 62 6f 76 65 20 |ne of the above |
00002fb0 69 6e 74 65 72 72 75 70 74 73 20 68 61 73 20 6f |interrupts has o|
00002fc0 63 63 75 72 65 64 20 7c 0d 2b 2d 2d 2d 2b 2d 2d |ccured |.+---+--|
00002fd0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00002fe0 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d 2d 2d 2d 2d 2d |-------+--------|
00002ff0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00003010 2d 2b 0d 0d 46 69 67 75 72 65 20 33 2e 20 54 68 |-+..Figure 3. Th|
00003020 65 20 69 6e 74 65 72 70 72 65 74 61 74 69 6f 6e |e interpretation|
00003030 20 6f 66 20 56 49 41 2d 42 20 49 46 52 20 28 6d | of VIA-B IFR (m|
00003040 6f 75 73 65 20 63 6f 6e 6e 65 63 74 65 64 20 74 |ouse connected t|
00003050 6f 20 55 73 65 72 20 50 6f 72 74 29 0d 2d 2d 2d |o User Port).---|
00003060 2d 2d 2d 2d 2d 2d 20 2d 2d 2d 2d 2d 2d 2d 2d 2d |------ ---------|
00003070 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
000030a0 2d 2d 2d 2d 2d 0d 0d 0d 41 6e 20 69 6e 74 65 72 |-----...An inter|
000030b0 72 75 70 74 20 68 61 6e 64 6c 69 6e 67 20 72 6f |rupt handling ro|
000030c0 75 74 69 6e 65 20 73 68 6f 75 6c 64 20 69 6e 74 |utine should int|
000030d0 65 72 6f 67 61 74 65 20 62 69 74 73 20 37 2c 20 |erogate bits 7, |
000030e0 33 20 61 6e 64 20 34 20 6f 66 20 74 68 65 20 49 |3 and 4 of the I|
000030f0 46 52 0d 74 6f 20 66 69 6e 64 20 6f 75 74 20 69 |FR.to find out i|
00003100 66 20 61 20 6d 6f 75 73 65 20 63 6f 6e 6e 65 63 |f a mouse connec|
00003110 74 65 64 20 74 6f 20 74 68 65 20 55 73 65 72 20 |ted to the User |
00003120 50 6f 72 74 20 69 73 20 74 68 65 20 73 6f 75 72 |Port is the sour|
00003130 63 65 20 6f 66 20 61 6e 20 49 52 51 0d 69 6e 74 |ce of an IRQ.int|
00003140 65 72 72 75 70 74 2e 20 42 69 74 73 20 37 20 61 |errupt. Bits 7 a|
00003150 6e 64 20 33 20 77 69 6c 6c 20 62 65 20 73 65 74 |nd 3 will be set|
00003160 20 69 66 20 74 68 65 20 6d 6f 75 73 65 20 69 73 | if the mouse is|
00003170 20 6d 6f 76 65 64 20 75 70 20 6f 72 20 64 6f 77 | moved up or dow|
00003180 6e 20 61 6e 64 0d 62 69 74 73 20 37 20 61 6e 64 |n and.bits 7 and|
00003190 20 34 20 77 69 6c 6c 20 62 65 20 73 65 74 20 69 | 4 will be set i|
000031a0 66 20 74 68 65 20 6d 6f 75 73 65 20 69 73 20 6d |f the mouse is m|
000031b0 6f 76 65 64 20 66 72 6f 6d 20 73 69 64 65 20 74 |oved from side t|
000031c0 6f 20 73 69 64 65 2e 20 49 66 20 61 0d 6d 6f 75 |o side. If a.mou|
000031d0 73 65 20 69 73 20 74 68 65 20 73 6f 75 72 63 65 |se is the source|
000031e0 20 6f 66 20 61 6e 20 69 6e 74 65 72 72 75 70 74 | of an interrupt|
000031f0 20 74 68 65 6e 20 74 68 65 20 69 6e 74 65 72 72 | then the interr|
00003200 75 70 74 20 6d 75 73 74 20 62 65 20 63 6c 65 61 |upt must be clea|
00003210 72 65 64 20 62 79 0d 72 65 61 64 69 6e 67 20 74 |red by.reading t|
00003220 68 65 20 63 6f 6e 74 65 6e 74 73 20 6f 66 20 44 |he contents of D|
00003230 52 42 20 28 62 65 63 61 75 73 65 20 62 69 74 20 |RB (because bit |
00003240 35 20 6f 66 20 74 68 65 20 50 43 52 20 69 73 20 |5 of the PCR is |
00003250 63 6c 65 61 72 29 2e 20 59 6f 75 20 63 61 6e 0d |clear). You can.|
00003260 74 68 65 72 65 66 6f 72 65 20 72 65 61 64 20 74 |therefore read t|
00003270 68 65 20 64 61 74 61 20 6c 69 6e 65 73 20 61 6e |he data lines an|
00003280 64 20 63 6c 65 61 72 20 74 68 65 20 69 6e 74 65 |d clear the inte|
00003290 72 72 75 70 74 20 61 74 20 74 68 65 20 73 61 6d |rrupt at the sam|
000032a0 65 20 74 69 6d 65 2e 0d 0d 54 68 65 20 70 6c 61 |e time...The pla|
000032b0 6e 65 20 6f 66 20 6d 6f 76 65 6d 65 6e 74 20 6f |ne of movement o|
000032c0 66 20 61 20 6d 6f 75 73 65 20 63 61 6e 20 62 65 |f a mouse can be|
000032d0 20 64 65 74 65 72 6d 69 6e 65 64 20 66 72 6f 6d | determined from|
000032e0 20 74 68 65 20 49 46 52 20 62 75 74 20 74 68 65 | the IFR but the|
000032f0 0d 64 69 72 65 63 74 69 6f 6e 20 6f 66 20 63 68 |.direction of ch|
00003300 61 6e 67 65 20 28 65 69 74 68 65 72 20 69 6e 63 |ange (either inc|
00003310 72 65 61 73 69 6e 67 20 6f 72 20 64 65 63 72 65 |reasing or decre|
00003320 61 73 69 6e 67 29 20 68 61 73 20 74 6f 20 62 65 |asing) has to be|
00003330 20 66 6f 75 6e 64 20 66 72 6f 6d 0d 74 68 65 20 | found from.the |
00003340 64 61 74 61 20 6c 69 6e 65 73 2e 20 41 20 6d 6f |data lines. A mo|
00003350 76 65 6d 65 6e 74 20 65 69 74 68 65 72 20 75 70 |vement either up|
00003360 20 6f 72 20 64 6f 77 6e 20 77 69 6c 6c 20 73 65 | or down will se|
00003370 74 20 62 69 74 20 33 20 6f 66 20 74 68 65 20 49 |t bit 3 of the I|
00003380 46 52 2e 20 49 66 0d 62 69 74 20 33 20 6f 66 20 |FR. If.bit 3 of |
00003390 74 68 65 20 49 46 52 20 69 73 20 73 65 74 20 79 |the IFR is set y|
000033a0 6f 75 72 20 70 72 6f 67 72 61 6d 20 73 68 6f 75 |our program shou|
000033b0 6c 64 20 74 65 73 74 20 62 69 74 20 32 20 6f 66 |ld test bit 2 of|
000033c0 20 64 61 74 61 20 72 65 67 69 73 74 65 72 20 42 | data register B|
000033d0 2e 0d 49 66 20 62 69 74 20 32 20 6f 66 20 44 52 |..If bit 2 of DR|
000033e0 42 20 69 73 20 73 65 74 20 74 68 65 6e 20 59 20 |B is set then Y |
000033f0 69 73 20 64 65 63 72 65 61 73 69 6e 67 20 62 75 |is decreasing bu|
00003400 74 20 69 66 20 69 74 20 69 73 20 63 6c 65 61 72 |t if it is clear|
00003410 20 74 68 65 6e 20 59 20 69 73 0d 69 6e 63 72 65 | then Y is.incre|
00003420 61 73 69 6e 67 2e 20 41 20 6d 6f 76 65 6d 65 6e |asing. A movemen|
00003430 74 20 66 72 6f 6d 20 73 69 64 65 20 74 6f 20 73 |t from side to s|
00003440 69 64 65 20 77 69 6c 6c 20 73 65 74 20 62 69 74 |ide will set bit|
00003450 20 34 20 6f 66 20 74 68 65 20 49 46 52 2e 20 59 | 4 of the IFR. Y|
00003460 6f 75 72 0d 70 72 6f 67 72 61 6d 20 73 68 6f 75 |our.program shou|
00003470 6c 64 20 74 68 65 6e 20 74 65 73 74 20 62 69 74 |ld then test bit|
00003480 20 30 20 6f 66 20 44 52 42 2e 20 49 66 20 69 74 | 0 of DRB. If it|
00003490 20 69 73 20 73 65 74 20 74 68 65 6e 20 58 20 69 | is set then X i|
000034a0 73 20 64 65 63 72 65 61 73 69 6e 67 2c 0d 69 66 |s decreasing,.if|
000034b0 20 69 74 20 69 73 20 63 6c 65 61 72 20 74 68 65 | it is clear the|
000034c0 6e 20 58 20 69 73 20 69 6e 63 72 65 61 73 69 6e |n X is increasin|
000034d0 67 2e 0d 0d 54 68 65 20 64 61 74 61 20 6c 69 6e |g...The data lin|
000034e0 65 73 20 61 6c 73 6f 20 67 69 76 65 20 74 68 65 |es also give the|
000034f0 20 73 74 61 74 75 73 20 6f 66 20 74 68 65 20 6d | status of the m|
00003500 6f 75 73 65 20 62 75 74 74 6f 6e 73 2e 20 50 72 |ouse buttons. Pr|
00003510 65 73 73 69 6e 67 20 74 68 65 0d 72 69 67 68 74 |essing the.right|
00003520 20 62 75 74 74 6f 6e 20 63 6c 65 61 72 73 20 62 | button clears b|
00003530 69 74 20 37 20 6f 66 20 44 52 42 2c 20 70 72 65 |it 7 of DRB, pre|
00003540 73 73 69 6e 67 20 74 68 65 20 63 65 6e 74 72 65 |ssing the centre|
00003550 20 62 75 74 74 6f 6e 20 63 6c 65 61 72 73 20 62 | button clears b|
00003560 69 74 20 36 0d 61 6e 64 20 74 68 65 20 6c 65 66 |it 6.and the lef|
00003570 74 20 62 75 74 74 6f 6e 20 63 6c 65 61 72 73 20 |t button clears |
00003580 62 69 74 20 35 2e 0d 0d 54 68 65 20 61 75 78 69 |bit 5...The auxi|
00003590 6c 69 61 72 79 20 63 6f 6e 74 72 6f 6c 20 72 65 |liary control re|
000035a0 67 69 73 74 65 72 20 69 73 20 6f 66 20 70 61 73 |gister is of pas|
000035b0 73 69 6e 67 20 69 6e 74 65 72 65 73 74 20 62 65 |sing interest be|
000035c0 63 61 75 73 65 20 69 74 20 63 61 6e 0d 65 69 74 |cause it can.eit|
000035d0 68 65 72 20 73 65 74 20 6f 72 20 63 6c 65 61 72 |her set or clear|
000035e0 20 6c 61 74 63 68 69 6e 67 20 74 68 65 20 64 61 | latching the da|
000035f0 74 61 20 6c 69 6e 65 73 20 6f 6e 20 61 20 73 69 |ta lines on a si|
00003600 67 6e 61 6c 20 66 72 6f 6d 20 43 42 31 2e 20 54 |gnal from CB1. T|
00003610 68 69 73 0d 77 6f 75 6c 64 20 62 65 20 71 75 69 |his.would be qui|
00003620 74 65 20 75 73 65 66 75 6c 20 69 66 20 74 68 65 |te useful if the|
00003630 20 6d 6f 75 73 65 20 68 61 64 20 62 65 65 6e 20 | mouse had been |
00003640 64 65 73 69 67 6e 65 64 20 74 6f 20 75 73 65 20 |designed to use |
00003650 6f 6e 6c 79 20 6f 6e 65 0d 68 61 6e 64 73 68 61 |only one.handsha|
00003660 6b 65 20 6c 69 6e 65 20 62 75 74 2c 20 62 65 63 |ke line but, bec|
00003670 61 75 73 65 20 69 74 20 75 73 65 73 20 62 6f 74 |ause it uses bot|
00003680 68 20 43 42 31 20 61 6e 64 20 43 42 32 20 61 73 |h CB1 and CB2 as|
00003690 20 69 6e 70 75 74 73 2c 20 74 68 65 20 64 61 74 | inputs, the dat|
000036a0 61 0d 6c 69 6e 65 73 20 63 61 6e 20 6f 6e 6c 79 |a.lines can only|
000036b0 20 62 65 20 6c 61 74 63 68 65 64 20 66 6f 72 20 | be latched for |
000036c0 6d 6f 76 65 6d 65 6e 74 20 69 6e 20 74 68 65 20 |movement in the |
000036d0 58 20 64 69 72 65 63 74 69 6f 6e 2e 20 54 68 69 |X direction. Thi|
000036e0 73 20 73 65 65 6d 73 20 74 6f 0d 62 65 20 61 20 |s seems to.be a |
000036f0 70 69 74 79 20 62 75 74 20 74 68 65 20 41 4d 58 |pity but the AMX|
00003700 20 64 65 73 69 67 6e 20 69 73 20 61 6e 20 69 6e | design is an in|
00003710 64 75 73 74 72 79 20 73 74 61 6e 64 61 72 64 20 |dustry standard |
00003720 66 6f 72 20 42 42 43 20 63 6f 6d 70 75 74 65 72 |for BBC computer|
00003730 73 20 61 6e 64 0d 77 65 20 68 61 76 65 20 74 6f |s and.we have to|
00003740 20 6c 69 76 65 20 77 69 74 68 20 69 74 2e 20 59 | live with it. Y|
00003750 6f 75 20 63 61 6e 20 63 6c 65 61 72 20 62 69 74 |ou can clear bit|
00003760 20 31 20 6f 66 20 74 68 65 20 41 43 52 20 74 6f | 1 of the ACR to|
00003770 20 64 69 73 61 62 6c 65 0d 6c 61 74 63 68 69 6e | disable.latchin|
00003780 67 20 74 68 65 20 64 61 74 61 20 6c 69 6e 65 73 |g the data lines|
00003790 20 70 72 69 6f 72 20 74 6f 20 75 73 69 6e 67 20 | prior to using |
000037a0 61 20 6d 6f 75 73 65 2e 20 54 68 65 20 41 43 52 |a mouse. The ACR|
000037b0 20 69 73 20 63 6c 65 61 72 65 64 20 62 79 0d 70 | is cleared by.p|
000037c0 72 65 73 73 69 6e 67 20 74 68 65 20 42 72 65 61 |ressing the Brea|
000037d0 6b 20 6b 65 79 2e 0d 0d 54 68 65 20 73 74 61 74 |k key...The stat|
000037e0 75 73 20 6f 66 20 74 68 65 20 49 46 52 20 61 6e |us of the IFR an|
000037f0 64 20 44 52 42 20 63 61 6e 20 62 65 20 64 65 6d |d DRB can be dem|
00003800 6f 6e 73 74 72 61 74 65 64 20 77 69 74 68 20 74 |onstrated with t|
00003810 68 65 20 70 72 6f 67 72 61 6d 0d 54 45 53 54 4d |he program.TESTM|
00003820 4f 55 2e 20 54 68 69 73 20 70 72 6f 67 72 61 6d |OU. This program|
00003830 20 64 6f 65 73 20 6e 6f 74 20 65 6e 61 62 6c 65 | does not enable|
00003840 20 74 68 65 20 6d 6f 75 73 65 20 67 65 6e 65 72 | the mouse gener|
00003850 61 74 65 64 20 69 6e 74 65 72 72 75 70 74 73 20 |ated interrupts |
00003860 62 75 74 0d 69 74 20 64 6f 65 73 20 73 68 6f 77 |but.it does show|
00003870 20 74 68 65 20 63 6f 6e 74 69 6e 75 6f 75 73 6c | the continuousl|
00003880 79 20 75 70 64 61 74 65 64 20 62 69 6e 61 72 79 |y updated binary|
00003890 20 73 74 61 74 75 73 20 6f 66 20 74 68 65 20 49 | status of the I|
000038a0 46 52 20 61 6e 64 20 44 52 42 2e 0d 43 6f 6e 6e |FR and DRB..Conn|
000038b0 65 63 74 20 79 6f 75 72 20 6d 6f 75 73 65 20 74 |ect your mouse t|
000038c0 6f 20 74 68 65 20 63 6f 6d 70 75 74 65 72 2c 20 |o the computer, |
000038d0 73 77 69 74 63 68 20 6f 6e 2c 20 63 68 61 69 6e |switch on, chain|
000038e0 20 74 68 65 20 70 72 6f 67 72 61 6d 20 54 45 53 | the program TES|
000038f0 54 4d 4f 55 0d 61 6e 64 20 6d 6f 76 65 20 74 68 |TMOU.and move th|
00003900 65 20 6d 6f 75 73 65 20 61 72 6f 75 6e 64 2e 20 |e mouse around. |
00003910 42 69 74 20 37 20 6f 66 20 74 68 65 20 49 46 52 |Bit 7 of the IFR|
00003920 20 69 73 20 61 6c 77 61 79 73 20 63 6c 65 61 72 | is always clear|
00003930 20 62 65 63 61 75 73 65 0d 69 6e 74 65 72 72 75 | because.interru|
00003940 70 74 73 20 68 61 76 65 20 6e 6f 74 20 62 65 65 |pts have not bee|
00003950 6e 20 65 6e 61 62 6c 65 64 2e 20 4d 6f 76 65 20 |n enabled. Move |
00003960 74 68 65 20 6d 6f 75 73 65 20 71 75 69 63 6b 6c |the mouse quickl|
00003970 79 20 74 6f 20 65 69 74 68 65 72 20 74 68 65 0d |y to either the.|
00003980 6c 65 66 74 20 6f 72 20 72 69 67 68 74 2e 20 59 |left or right. Y|
00003990 6f 75 20 73 68 6f 75 6c 64 20 73 65 65 20 43 42 |ou should see CB|
000039a0 31 20 73 65 74 20 77 68 69 6c 65 20 69 74 20 69 |1 set while it i|
000039b0 73 20 6d 6f 76 69 6e 67 20 61 6e 64 20 63 6c 65 |s moving and cle|
000039c0 61 72 20 61 73 20 73 6f 6f 6e 0d 61 73 20 69 74 |ar as soon.as it|
000039d0 20 73 74 6f 70 73 2e 20 53 69 6d 69 6c 61 72 6c | stops. Similarl|
000039e0 79 20 6d 6f 76 65 20 74 68 65 20 6d 6f 75 73 65 |y move the mouse|
000039f0 20 71 75 69 63 6b 6c 79 20 75 70 20 61 6e 64 20 | quickly up and |
00003a00 64 6f 77 6e 20 74 6f 20 73 65 65 20 74 68 65 20 |down to see the |
00003a10 73 61 6d 65 0d 65 66 66 65 63 74 20 6f 6e 20 43 |same.effect on C|
00003a20 42 32 2e 20 41 74 20 74 68 65 20 73 61 6d 65 20 |B2. At the same |
00003a30 74 69 6d 65 20 79 6f 75 20 77 69 6c 6c 20 73 65 |time you will se|
00003a40 65 20 62 69 74 73 20 30 20 61 6e 64 20 32 20 6f |e bits 0 and 2 o|
00003a50 66 20 44 52 42 20 63 68 61 6e 67 69 6e 67 0d 73 |f DRB changing.s|
00003a60 74 61 74 65 2e 20 59 6f 75 20 63 61 6e 20 61 6c |tate. You can al|
00003a70 73 6f 20 73 65 65 20 74 68 65 20 65 66 66 65 63 |so see the effec|
00003a80 74 20 74 68 61 74 20 70 72 65 73 73 69 6e 67 20 |t that pressing |
00003a90 74 68 65 20 6d 6f 75 73 65 20 62 75 74 74 6f 6e |the mouse button|
00003aa0 73 20 68 61 73 20 6f 6e 0d 44 52 42 2e 0d 0d 54 |s has on.DRB...T|
00003ab0 68 69 73 20 6d 6f 64 75 6c 65 20 68 61 73 20 65 |his module has e|
00003ac0 78 70 6c 61 69 6e 65 64 20 77 68 65 72 65 20 74 |xplained where t|
00003ad0 6f 20 66 69 6e 64 20 74 68 65 20 64 61 74 61 20 |o find the data |
00003ae0 70 72 6f 64 75 63 65 64 20 62 79 20 61 20 6d 6f |produced by a mo|
00003af0 75 73 65 2e 20 54 68 65 0d 66 6f 6c 6c 6f 77 69 |use. The.followi|
00003b00 6e 67 20 6d 6f 64 75 6c 65 73 20 77 69 6c 6c 20 |ng modules will |
00003b10 65 78 70 6c 61 69 6e 20 68 6f 77 20 74 68 65 73 |explain how thes|
00003b20 65 20 64 61 74 61 20 63 61 6e 20 62 65 20 69 6e |e data can be in|
00003b30 74 65 72 70 72 65 74 65 64 20 61 6e 64 20 75 73 |terpreted and us|
00003b40 65 64 2e 0d 0d 0d 20 20 20 31 30 20 52 45 4d 3e |ed.... 10 REM>|
00003b50 20 54 45 53 54 4d 4f 55 0d 20 20 20 32 30 20 44 | TESTMOU. 20 D|
00003b60 49 4d 20 6d 63 6f 64 65 20 26 31 30 30 20 3a 52 |IM mcode &100 :R|
00003b70 45 4d 3a 20 6d 61 63 68 69 6e 65 20 63 6f 64 65 |EM: machine code|
00003b80 20 61 74 20 6d 63 6f 64 65 0d 20 20 20 33 30 20 | at mcode. 30 |
00003b90 65 73 63 61 70 65 3d 26 46 46 20 3a 52 45 4d 3a |escape=&FF :REM:|
00003ba0 20 65 73 63 61 70 65 20 66 6c 61 67 0d 20 20 20 | escape flag. |
00003bb0 34 30 20 64 72 62 3d 26 46 45 36 30 20 3a 52 45 |40 drb=&FE60 :RE|
00003bc0 4d 3a 20 64 61 74 61 20 72 65 67 69 73 74 65 72 |M: data register|
00003bd0 20 42 0d 20 20 20 35 30 20 64 64 72 62 3d 26 46 | B. 50 ddrb=&F|
00003be0 45 36 32 20 3a 52 45 4d 3a 20 64 61 74 61 20 64 |E62 :REM: data d|
00003bf0 69 72 65 63 74 69 6f 6e 20 72 65 67 69 73 74 65 |irection registe|
00003c00 72 20 42 0d 20 20 20 36 30 20 69 66 72 3d 26 46 |r B. 60 ifr=&F|
00003c10 45 36 44 20 3a 52 45 4d 3a 20 69 6e 74 65 72 72 |E6D :REM: interr|
00003c20 75 70 74 20 66 6c 61 67 20 72 65 67 69 73 74 65 |upt flag registe|
00003c30 72 0d 20 20 20 37 30 20 6f 73 77 72 63 68 3d 26 |r. 70 oswrch=&|
00003c40 46 46 45 45 0d 20 20 20 38 30 20 6f 73 62 79 74 |FFEE. 80 osbyt|
00003c50 65 3d 26 46 46 46 34 0d 20 20 20 39 30 20 46 4f |e=&FFF4. 90 FO|
00003c60 52 20 70 61 73 73 3d 30 20 54 4f 20 32 20 53 54 |R pass=0 TO 2 ST|
00003c70 45 50 20 32 0d 20 20 31 30 30 20 50 25 3d 6d 63 |EP 2. 100 P%=mc|
00003c80 6f 64 65 0d 20 20 31 31 30 20 5b 20 20 20 20 20 |ode. 110 [ |
00003c90 20 20 4f 50 54 20 70 61 73 73 0d 20 20 31 32 30 | OPT pass. 120|
00003ca0 20 20 20 20 20 20 20 20 20 4c 44 41 20 23 26 30 | LDA #&0|
00003cb0 30 0d 20 20 31 33 30 20 20 20 20 20 20 20 20 20 |0. 130 |
00003cc0 53 54 41 20 64 64 72 62 20 20 20 20 20 20 5c 20 |STA ddrb \ |
00003cd0 64 61 74 61 20 72 65 67 69 73 74 65 72 20 42 20 |data register B |
00003ce0 3d 20 69 6e 70 75 74 0d 20 20 31 34 30 20 2e 6d |= input. 140 .m|
00003cf0 61 69 6e 6c 6f 6f 70 0d 20 20 31 35 30 20 20 20 |ainloop. 150 |
00003d00 20 20 20 20 20 20 4c 44 58 20 23 31 36 0d 20 20 | LDX #16. |
00003d10 31 36 30 20 20 20 20 20 20 20 20 20 4c 44 59 20 |160 LDY |
00003d20 23 31 36 0d 20 20 31 37 30 20 20 20 20 20 20 20 |#16. 170 |
00003d30 20 20 4a 53 52 20 76 64 75 20 20 20 20 20 20 20 | JSR vdu |
00003d40 5c 20 56 44 55 20 33 31 2c 31 36 2c 31 36 0d 20 |\ VDU 31,16,16. |
00003d50 20 31 38 30 20 20 20 20 20 20 20 20 20 4c 44 41 | 180 LDA|
00003d60 20 64 72 62 20 20 20 20 20 20 20 5c 20 64 61 74 | drb \ dat|
00003d70 61 20 72 65 67 69 73 74 65 72 20 42 0d 20 20 31 |a register B. 1|
00003d80 39 30 20 20 20 20 20 20 20 20 20 4a 53 52 20 62 |90 JSR b|
00003d90 69 6e 61 72 79 20 20 20 20 5c 20 70 72 69 6e 74 |inary \ print|
00003da0 20 44 52 42 20 69 6e 20 62 69 6e 61 72 79 0d 20 | DRB in binary. |
00003db0 20 32 30 30 20 20 20 20 20 20 20 20 20 4c 44 58 | 200 LDX|
00003dc0 20 23 31 36 0d 20 20 32 31 30 20 20 20 20 20 20 | #16. 210 |
00003dd0 20 20 20 4c 44 59 20 23 31 38 0d 20 20 32 32 30 | LDY #18. 220|
00003de0 20 20 20 20 20 20 20 20 20 4a 53 52 20 76 64 75 | JSR vdu|
00003df0 20 20 20 20 20 20 20 5c 20 56 44 55 20 33 31 2c | \ VDU 31,|
00003e00 31 36 2c 31 38 0d 20 20 32 33 30 20 20 20 20 20 |16,18. 230 |
00003e10 20 20 20 20 4c 44 41 20 69 66 72 20 20 20 20 20 | LDA ifr |
00003e20 20 20 5c 20 69 6e 74 65 72 72 75 70 74 20 66 6c | \ interrupt fl|
00003e30 61 67 20 72 65 67 69 73 74 65 72 0d 20 20 32 34 |ag register. 24|
00003e40 30 20 20 20 20 20 20 20 20 20 4a 53 52 20 62 69 |0 JSR bi|
00003e50 6e 61 72 79 20 20 20 20 5c 20 70 72 69 6e 74 20 |nary \ print |
00003e60 49 46 52 20 69 6e 20 62 69 6e 61 72 79 0d 20 20 |IFR in binary. |
00003e70 32 35 30 20 20 20 20 20 20 20 20 20 4c 44 41 20 |250 LDA |
00003e80 65 73 63 61 70 65 20 20 20 20 5c 20 70 6f 6c 6c |escape \ poll|
00003e90 20 74 68 65 20 65 73 63 61 70 65 20 66 6c 61 67 | the escape flag|
00003ea0 0d 20 20 32 36 30 20 20 20 20 20 20 20 20 20 42 |. 260 B|
00003eb0 50 4c 20 6d 61 69 6e 6c 6f 6f 70 20 20 5c 20 6c |PL mainloop \ l|
00003ec0 6f 6f 70 20 69 66 20 65 73 63 61 70 65 20 6e 6f |oop if escape no|
00003ed0 74 20 70 72 65 73 73 65 64 0d 20 20 32 37 30 20 |t pressed. 270 |
00003ee0 20 20 20 20 20 20 20 20 4c 44 41 20 23 26 37 45 | LDA #&7E|
00003ef0 20 20 20 20 20 20 5c 20 61 63 6b 6e 6f 77 6c 65 | \ acknowle|
00003f00 64 67 65 20 64 65 74 65 63 74 69 6f 6e 20 6f 66 |dge detection of|
00003f10 20 61 6e 20 45 73 63 61 70 65 20 63 6f 6e 64 69 | an Escape condi|
00003f20 74 69 6f 6e 0d 20 20 32 38 30 20 20 20 20 20 20 |tion. 280 |
00003f30 20 20 20 4a 4d 50 20 6f 73 62 79 74 65 20 20 20 | JMP osbyte |
00003f40 20 5c 20 61 63 6b 6e 6f 77 6c 65 64 67 65 20 45 | \ acknowledge E|
00003f50 73 63 61 70 65 20 61 6e 64 20 72 65 74 75 72 6e |scape and return|
00003f60 20 74 6f 20 42 41 53 49 43 0d 20 20 32 39 30 20 | to BASIC. 290 |
00003f70 2e 62 69 6e 61 72 79 0d 20 20 33 30 30 20 20 20 |.binary. 300 |
00003f80 20 20 20 20 20 20 4c 44 58 20 23 26 30 38 20 20 | LDX #&08 |
00003f90 20 20 20 20 5c 20 62 69 74 20 63 6f 75 6e 74 65 | \ bit counte|
00003fa0 72 0d 20 20 33 31 30 20 2e 6e 65 78 74 62 69 74 |r. 310 .nextbit|
00003fb0 0d 20 20 33 32 30 20 20 20 20 20 20 20 20 20 41 |. 320 A|
00003fc0 53 4c 20 41 20 20 20 20 20 20 20 20 20 5c 20 6e |SL A \ n|
00003fd0 65 78 74 20 62 69 74 20 69 6e 74 6f 20 63 61 72 |ext bit into car|
00003fe0 72 79 20 66 6c 61 67 0d 20 20 33 33 30 20 20 20 |ry flag. 330 |
00003ff0 20 20 20 20 20 20 50 48 41 20 20 20 20 20 20 20 | PHA |
00004000 20 20 20 20 5c 20 73 61 76 65 20 74 68 65 20 72 | \ save the r|
00004010 65 73 74 20 6f 66 20 74 68 65 20 62 79 74 65 0d |est of the byte.|
00004020 20 20 33 34 30 20 20 20 20 20 20 20 20 20 4c 44 | 340 LD|
00004030 41 20 23 41 53 43 28 22 30 22 29 20 5c 20 69 66 |A #ASC("0") \ if|
00004040 20 63 61 72 72 79 20 63 6c 65 61 72 20 70 72 69 | carry clear pri|
00004050 6e 74 20 30 0d 20 20 33 35 30 20 20 20 20 20 20 |nt 0. 350 |
00004060 20 20 20 41 44 43 20 23 26 30 30 20 20 20 20 20 | ADC #&00 |
00004070 20 5c 20 69 66 20 63 61 72 72 79 20 73 65 74 20 | \ if carry set |
00004080 61 64 64 20 31 0d 20 20 33 36 30 20 20 20 20 20 |add 1. 360 |
00004090 20 20 20 20 4a 53 52 20 6f 73 77 72 63 68 20 20 | JSR oswrch |
000040a0 20 20 5c 20 70 72 69 6e 74 20 30 20 6f 72 20 31 | \ print 0 or 1|
000040b0 0d 20 20 33 37 30 20 20 20 20 20 20 20 20 20 50 |. 370 P|
000040c0 4c 41 20 20 20 20 20 20 20 20 20 20 20 5c 20 72 |LA \ r|
000040d0 65 73 74 6f 72 65 20 74 68 65 20 72 65 73 74 20 |estore the rest |
000040e0 6f 66 20 74 68 65 20 62 79 74 65 0d 20 20 33 38 |of the byte. 38|
000040f0 30 20 20 20 20 20 20 20 20 20 44 45 58 20 20 20 |0 DEX |
00004100 20 20 20 20 20 20 20 20 5c 20 64 65 63 72 65 6d | \ decrem|
00004110 65 6e 74 20 62 69 74 20 63 6f 75 6e 74 65 72 0d |ent bit counter.|
00004120 20 20 33 39 30 20 20 20 20 20 20 20 20 20 42 4e | 390 BN|
00004130 45 20 6e 65 78 74 62 69 74 20 20 20 5c 20 62 72 |E nextbit \ br|
00004140 61 6e 63 68 20 66 6f 72 20 6e 65 78 74 20 62 69 |anch for next bi|
00004150 74 0d 20 20 34 30 30 20 20 20 20 20 20 20 20 20 |t. 400 |
00004160 52 54 53 0d 20 20 34 31 30 20 2e 76 64 75 0d 20 |RTS. 410 .vdu. |
00004170 20 34 32 30 20 20 20 20 20 20 20 20 20 4c 44 41 | 420 LDA|
00004180 20 23 33 31 0d 20 20 34 33 30 20 20 20 20 20 20 | #31. 430 |
00004190 20 20 20 4a 53 52 20 6f 73 77 72 63 68 20 20 20 | JSR oswrch |
000041a0 20 5c 20 56 44 55 20 33 31 0d 20 20 34 34 30 20 | \ VDU 31. 440 |
000041b0 20 20 20 20 20 20 20 20 54 58 41 0d 20 20 34 35 | TXA. 45|
000041c0 30 20 20 20 20 20 20 20 20 20 4a 53 52 20 6f 73 |0 JSR os|
000041d0 77 72 63 68 20 20 20 20 5c 20 56 44 55 20 58 0d |wrch \ VDU X.|
000041e0 20 20 34 36 30 20 20 20 20 20 20 20 20 20 54 59 | 460 TY|
000041f0 41 0d 20 20 34 37 30 20 20 20 20 20 20 20 20 20 |A. 470 |
00004200 4a 4d 50 20 6f 73 77 72 63 68 20 20 20 20 5c 20 |JMP oswrch \ |
00004210 56 44 55 20 59 20 61 6e 64 20 72 65 74 75 72 6e |VDU Y and return|
00004220 0d 20 20 34 38 30 20 5d 0d 20 20 34 39 30 20 4e |. 480 ]. 490 N|
00004230 45 58 54 0d 20 20 35 30 30 20 4d 4f 44 45 37 0d |EXT. 500 MODE7.|
00004240 20 20 35 31 30 20 56 44 55 32 33 2c 31 2c 30 3b | 510 VDU23,1,0;|
00004250 30 3b 30 3b 30 3b 0d 20 20 35 32 30 20 6d 6f 75 |0;0;0;. 520 mou|
00004260 73 65 24 3d 43 48 52 24 31 34 31 2b 43 48 52 24 |se$=CHR$141+CHR$|
00004270 31 33 32 2b 43 48 52 24 31 35 37 2b 43 48 52 24 |132+CHR$157+CHR$|
00004280 31 33 31 0d 20 20 20 20 20 20 2b 22 55 73 65 72 |131. +"User|
00004290 20 70 6f 72 74 20 69 6e 70 75 74 20 61 6e 64 20 | port input and |
000042a0 73 74 61 74 75 73 20 62 79 74 65 73 20 20 22 2b |status bytes "+|
000042b0 43 48 52 24 31 35 36 0d 20 20 35 33 30 20 50 52 |CHR$156. 530 PR|
000042c0 49 4e 54 54 41 42 28 30 2c 35 29 6d 6f 75 73 65 |INTTAB(0,5)mouse|
000042d0 24 0d 20 20 35 34 30 20 50 52 49 4e 54 54 41 42 |$. 540 PRINTTAB|
000042e0 28 30 2c 36 29 6d 6f 75 73 65 24 0d 20 20 35 35 |(0,6)mouse$. 55|
000042f0 30 20 50 52 49 4e 54 54 41 42 28 31 36 2c 31 34 |0 PRINTTAB(16,14|
00004300 29 22 37 36 35 34 33 32 31 30 22 0d 20 20 35 36 |)"76543210". 56|
00004310 30 20 50 52 49 4e 54 54 41 42 28 39 2c 31 36 29 |0 PRINTTAB(9,16)|
00004320 22 26 46 45 36 30 20 25 20 20 20 20 20 20 20 20 |"&FE60 % |
00004330 20 44 52 42 22 0d 20 20 35 37 30 20 50 52 49 4e | DRB". 570 PRIN|
00004340 54 54 41 42 28 39 2c 31 38 29 22 26 46 45 36 44 |TTAB(9,18)"&FE6D|
00004350 20 25 20 20 20 20 20 20 20 20 20 49 46 52 22 0d | % IFR".|
00004360 20 20 35 38 30 20 50 52 49 4e 54 54 41 42 28 31 | 580 PRINTTAB(1|
00004370 39 2c 32 30 29 22 43 43 22 0d 20 20 35 39 30 20 |9,20)"CC". 590 |
00004380 50 52 49 4e 54 54 41 42 28 31 39 2c 32 31 29 22 |PRINTTAB(19,21)"|
00004390 42 42 22 0d 20 20 36 30 30 20 50 52 49 4e 54 54 |BB". 600 PRINTT|
000043a0 41 42 28 31 39 2c 32 32 29 22 31 32 22 0d 20 20 |AB(19,22)"12". |
000043b0 36 31 30 20 43 41 4c 4c 20 6d 63 6f 64 65 0d 20 |610 CALL mcode. |
000043c0 20 36 32 30 20 56 44 55 33 31 2c 30 2c 32 34 0d | 620 VDU31,0,24.|
000043d0 20 20 36 33 30 20 56 44 55 32 33 2c 31 2c 31 3b | 630 VDU23,1,1;|
000043e0 30 3b 30 3b 30 3b 0d 20 20 36 34 30 20 45 4e 44 |0;0;0;. 640 END|
000043f0 0d |.|
000043f1 
18-11-88/T\MOU00.m0
18-11-88/T\MOU00.m1
18-11-88/T\MOU00.m2
18-11-88/T\MOU00.m4
18-11-88/T\MOU00.m5
.