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13-08-88/T\DFS01
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 » telesoftware8.adl |
| Filename: | 13-08-88/T\DFS01 |
| Read OK: | ✔ |
| File size: | 6682 bytes |
| Load address: | 0000 |
| Exec address: | FFFFFFFF |
File contents
The Acorn DFS Osword commands - by - Gordon Horsington
----------------------------------------------------------
Module 1. The DFS Osword commands (part 1)
------------------------------------------
+----------------------------------------------------------+
| All the DFS modules in this series use programs which |
| experiment with the format and contents of discs. These |
| experiments may have disasterous effects if you use any |
| of the programs on discs which store programs or data |
| which you cannot afford to lose. You should first try |
| out the programs using discs that have either been |
| duplicated or, better still, have not been used at all. |
+----------------------------------------------------------+
The DFS ROM intercepts and recognises three Osword calls. Osword &7D reads
the number of times a disk has been written, Osword &7E reads the number
of sectors on a disc, and Osword &7F executes the 8271 disc controller
commands.
----------
Osword &7D
----------
Osword &7D reads the catalogue for the current default disc, as specified
by the most recent *DRIVE command, and extracts the number of disc cycles
from the catalogue. The number of disc cycles is a BCD number in the range
from 0 to 99. This number gives some indication of how many times the disc
has been written. Because The disc cycle number restarts at 0 after
reaching 99 this is not a reliable count.
The catalogue is read by Osword &7D and stored in the first two pages of
the paged ROM absolute workspace (pages &0E and &0F with OS 1.2). The
result is stored in a one byte parameter block specified by X and Y
registers on entry. The program CYCLES demonstrates how Osword &7D can be
used to read the disc cycles.
10 REM: CYCLES
20 osword=&FFF1
30 DIM mcode &100
40 FOR pass = 0 TO 2 STEP 2
50 P%=mcode
60 [ OPT pass
70 LDA #&7D
80 LDX #result MOD 256
90 LDY #result DIV 256
100 JSR osword
110 RTS
120 .result
130 EQUB &00
140 ]
150 NEXT
160 CALL mcode
170 PRINT"Disc cycles = ";~?result
----------
Osword &7E
----------
Osword &7E reads the catalogue for the current default disc, as specified
by the most recent *DRIVE command, and extracts the number of sectors
available on the disc. There are 800 (&320) sectors on an 80 track Acorn
DFS disc and 400 (&190) sectors on a 40 track Acorn DFS disc. Non-standard
and copy-protected discs may have different numbers of available sectors.
The catalogue is read by Osword &7E and stored in the first two pages of
the paged ROM absolute workspace (pages &0E and &0F with OS 1.2). The
result is stored in a four byte parameter block specified by the X and Y
registers on entry. The program HOWMANY demonstrates how Osword &7E can be
used to read the number of available sectors on a DFS disc. The least
significant byte of the number of sectors will be in byte &01 of the
result and the most significant byte in byte &02 of the result. Bytes &00
and &03 of the result should always be zero.
10 REM: HOWMANY
20 osword=&FFF1
30 DIM mcode &100
40 FOR pass = 0 TO 2 STEP 2
50 P%=mcode
60 [ OPT pass
70 LDA #&7E
80 LDX #result MOD 256
90 LDY #result DIV 256
100 JSR osword
110 RTS
120 .result
130 EQUD &00
140 ]
150 NEXT
160 CALL mcode
170 PRINT"&";~result?2;~result?1;" Sectors"
----------
Osword &7F
----------
Osword &7F executes the 8271 disc controller commands. If the disc
interface uses a 1770 disc controller then Osword &7F emulates the 8271
command set using the 1770. The complete command set executed by Osword
&7F is shown in figure 1. Not all the 8271 commands can be emulated by the
1770 and the Osword &7F commands from &6C to &7D are not fully implemented
with the Acorn 1770 disc interface.
When you write software which uses the Osword &7F commands from &6C to &7D
you should take care to ensure that your programs will work with the 1770
disc controller as well as with the 8271 interface. Some of the example
programs used in this module use these partly implemented Osword &7F
commands and may not work as expected with all 1770 disc interfaces. The
programs used to illustrate the other Osword &7F commands all work with
the Acorn 1770 DFS.
+---------+--------+------+-------------------------------------------+
| Command | Param- | 1770 | Action |
| number | eters | | |
+---------+--------+------+-------------------------------------------+
| &4A | 2 | Yes | Write data 128 bytes |
| &4B | 3 | Yes | Write data multi-sector |
| &4E | 2 | Yes | Write deleted data 128 bytes |
| &4F | 3 | Yes | Write deleted data multi-sector |
| &52 | 2 | Yes | Read data 128 bytes |
| &53 | 3 | Yes | Read data multi-sector |
| &56 | 2 | Yes | Read data and deleted data 128 bytes |
| &57 | 3 | Yes | Read data and deleted data multi-sector |
| &5B | 3 | Yes | Read sector ids |
| &5E | 2 | Yes | Verify data and deleted data 128 bytes |
| &5F | 3 | Yes | Verify data and deleted data multi-sector |
| &63 | 5 | Yes | Format track |
| &69 | 1 | Yes | Seek |
+---------+--------+------+-------------------------------------------+
| &6C | 0 | Part | Read drive status |
| &75 | 4 | Part | Initialise 8271 |
| &75 | 4 | Part | Load bad tracks |
| &7A | 2 | Part | Write special register |
| &7D | 1 | Part | Read special register |
+---------+--------+------+-------------------------------------------+
Figure 1. The Osword &7F command set
------------------------------------
Osword &7F uses a variable length parameter block the address of which is
specified by the X and Y registers on entry.
Byte &00 of the parameter block is used to store the number of the disc
drive to be used with the command. If a negative drive number is used (&80
to &FF) then Osword &7F uses the currently selected drive as specified by
the most recent *DRIVE command.
Bytes &01 to &04 of the parameter block store the address of a buffer area
into which any data to be read will be placed, or from which any data to
be written will be taken. A buffer is not needed by all the commands but
bytes &01 to &04 of the parameter block are always assigned to a buffer
address even if a buffer is not used.
Column 2 of figure 1 shows that the Osword &7F commands use from 0 to 5
parameters. The number of parameters used by a call is stored in byte &05
of its parameter block. Byte &06 of the parameter block stores the command
number (column 1, figure 1), and byte &07 onwards the parameters required
by the command. The last byte of the parameter block is a result byte.
Unless it is used to read the 8271 registers, Osword &7F will normally
return the number zero in the result byte when a command has been executed
sucessfully but it returns the number &20 (ie. bit 5 set) if deleted data
have been sucessfully written to, read from, or verified on a disc.
The result is returned in byte &07 of the parameter block for Osword &7F
command number &6C, which uses no parameters. It is returned in byte &08
of the parameter block for command numbers &69 and &7D, which use one
parameter, and so on up to byte &0C of the parameter block for command
number &63 which uses 5 parameters.
Errors are reported in bits 1 to 4 of the result byte. The error codes can
be isolated by ANDing the result byte with #&1E and the error codes can be
interpreted as shown in figure 2.
+--------+----------------------------+
| Result | Interpretation |
+--------+----------------------------+
| &02 | Scan met equal ** |
| &04 | Scan met not equal ** |
| &08 | Clock error |
| &0A | Late DMA ** |
| &0C | Sector ID CRC error |
| &0E | Data CRC error |
| &10 | Drive not ready |
| &12 | Disc write protected |
| &14 | Physical track 0 not found |
| &16 | Write fault |
| &18 | Sector not found |
+--------+----------------------------+
| Errors marked ** should not occur |
+-------------------------------------+
Figure 2. The error codes returned in the result byte
-----------------------------------------------------
When designing software which uses Osword &7F you can test the result byte
for specific errors after ANDing the result with #&1E to isolate the error
bits. ANDing with #&1E excludes the deleted data bit which is not really
an error at all. Testing for specific errors is not essential because all
the above errors are fatal and any error should be used to halt your
program. Testing for specific errors can always give some useful extra
information when a routine fails to work as expected.
In the rest of this module and whole of the next module I will discuss the
commands executed by Osword &7F and give short examples of the some of
them. Later in the series these commands will be used to show you how to
create disc utility programs.
The order in which the commands will be discussed is not the order in
which they are listed in figure 1. I will cover the Osword &7F command
numbers &69 to &7D in this module. With the exception of the Seek command,
these commands are not fuly implemented with the 1770 disc interface but
they are effectivly incorporated in other commands such as Write Data,
Read Data, and Verify. The Osword &7F command numbers &4A to &63 will be
covered in the next module.
----------------------------
Osword &7F Read Drive Status
----------------------------
The Osword &7F Read Drive Status command copies the 8271 drive control
input register to the parameter block result byte. To use this command set
up the following parameter block.
Parameter block &00 = drive number (&00-&03 or &FF)
Parameter block &01 - &04 = buffer address (not used)
Parameter block &05 = &00 (no command parameters)
Parameter block &06 = &6C (read drive status command)
Parameter block &07 = result byte
Each bit of the result byte has the following meaning:
bit 7 = unused
bit 6 = READY1
bit 5 = FAULT
bit 4 = INDEX
bit 3 = WR PROTECT
bit 2 = READY0
bit 1 = TRK0
bit 0 = COUNT/OP1
These results are only really useful for tracking down hardware errors.
You can use the demonstration program STATUS with both write protected and
write enabled discs to see the effect that write protection has on the
bits of the result register. You could use this command to test for a
write protection tab on a disc but the only unique use for the Osword &7F
Read Drive Status command is to clear a "not ready" signal. It is used by
the DFS for this purpose. This is not one of the most useful commands and
you will probably not need to use it in any of your programs.
10 REM: STATUS
20 oswrch=&FFEE
30 osword=&FFF1
40 DIM mcode &100
50 FOR pass = 0 TO 2 STEP 2
60 P%=mcode
70 [ OPT pass
80 LDA #&7F
90 LDX #block MOD 256
100 LDY #block DIV 256
110 JSR osword
120 RTS
130 .block
140 EQUB &FF \ current drive
150 EQUD &00 \ does not matter
160 EQUB &00 \ 0 parameters
170 EQUB &6C \ read status command
180 .result
190 EQUB &00 \ result byte
200 .binary
210 LDX #8
220 .loop
230 LDA #ASC("0")
240 ASL result
250 ADC #&00
260 JSR oswrch
270 DEX
280 BNE loop
290 RTS
300 ]
310 NEXT
320 CALL mcode
330 PRINT"Result = &";~?result;", %";
340 CALL binary
350 PRINT
--------------------------
Osword &7F Initialise 8271
--------------------------
Osword &7F Initialise 8271 is not fully implemented with the 1770 disc
interface. For this reason you should avoid using it and use the
equivalent Osbyte &FF which is available from the operating system of all
BBC microcomputers.
The hardware default setting is equivalent to *FX 255,0,255 and this gives
access to the slowest disc drives. The Osbyte calls in figure 3 can be
used to give access to faster drives but, if you are writing software to
be used on unknown drives, it may be a good idea to select the slowest
time.
Osbyte &FF passes the values of the drive step time, settlement time, and
head load time to the disc controller on soft break and they will remain
in force until a hard break.
+-----------+-------------+-----------+---------------+
| Step time | Settle time | Load time | Osbyte &FF |
+-----------+-------------+-----------+---------------+
| 4 | 16 | 0 | *FX 255,0,207 |
| 6 | 16 | 0 | *FX 255,0,223 |
| 6 | 50 | 32 | *FX 255,0,239 |
| 24 | 20 | 64 | *FX 255,0,255 |
+-----------+-------------+-----------+---------------+
Figure 3. Disc access timings
-----------------------------
If you need to use the Osword &7F Initialise 8271 command then the
following parameter block must be used.
Parameter block &00 = drive number (&00-&03 or &FF)
Parameter block &01 - &04 = buffer address (not used)
Parameter block &05 = &04 (4 command parameters)
Parameter block &06 = &75 (initialise 8271 command)
Parameter block &07 = &0D (init 8271 marker)
Parameter block &08 = drive step time (milliseconds / 2)
Parameter block &09 = head settlement time (miliseconds / 2)
Parameter block &0A = head unload/load time (two 4 bit numbers)
Parameter block &0B = result byte
The drive step time should be in the range from &01 to &FF, representing 2
to 510 milliseconds in 2 millisecond steps. A drive step time of zero
indicates that the drive will provide its own step pulses.
The head settlement time should be in the range &00 to &FF representing a
delay of 0 to 512 miliseconds in 2 millisecond steps.
The four most significant bits of the head unload/load time should be in
the range %0000 to %1110 (0-14) representing the number of complete disc
revolutions before the head is unloaded. %1111 specifies that the head
should not be unloaded at all. The four least significant bits of the head
unload/load time specify the time taken to load the head in 8 milisecond
intervals. This is a number in the range %0000 to %1111 (0-15)
representing head load times of 0 to 120 milliseconds.
The following code could be used to initialise the 8271.
LDA #&7F
LDX #block MOD 256
LDY #block DIV 256
JSR &FFF1
RTS
.block
EQUB &FF \ current drive
EQUD &00 \ buffer address (not used)
EQUB &04 \ 4 parameters
EQUB &75 \ init 8271 command
EQUB 12 \ 24 milliseconds step time
EQUB 10 \ 20 milliseconds settle time
EQUB &C8 \ Unload = 12 revs, load =64 milliseconds
EQUB &00 \ result byte
---------------
Osword &7F Seek
---------------
The Osword &7F Seek command uses the appropriate track register as a base
from which to seek a specified physical track. Register number &12 is used
for drive 0/2 and register number &1A is used for drive 1/3. This command
does not load the head and does not check the sector IDs. If track 0 is
specified the seek command steps the head outwards until it trips the
track 0 switch. If the TRK0 signal is missing after 255 attempts to find
it, the command reports error &14 in the result byte. Error &14 is
physical track zero not found (see figure 2).
Seek track 0 can be used to find a base from which to seek any other
physical track. This can be useful if the track register contains an
unknown or incorrect physical track number.
The following parameter block is used to seek a physical track.
Parameter block &00 = drive number (&00-&03 or &FF)
Parameter block &01 - &04 = buffer address (not used)
Parameter block &05 = &01 (1 command parameter)
Parameter block &06 = &69 (seek command)
Parameter block &07 = physical track number
Parameter block &08 = result byte
The Osword &7F Seek command is useful if, for example, you want to write
data onto a copy-protected disc which uses different physical and logical
track numbers. You would use it to seek the physical track number and then
use the Osword &7F Write Special Register command to write the logical
track number into the appropriate track register. After writing to the
disc you should then either rewrite the physical track number into the
appropriate track register or seek track 0.
The following code could be used to seek track 0 on the current drive.
LDA #&7F
LDX #block MOD 256
LDY #block DIV 256
JSR &FFF1
RTS
.block
EQUB &FF \ current drive
EQUD &00 \ buffer address (not used)
EQUB &01 \ 1 parameter
EQUB &69 \ seek command
EQUB &00 \ track 0
EQUB &00 \ result byte
--------------------------
Osword &7F Load Bad Tracks
--------------------------
This command is used to tell the 8271 that there are one or two "bad
tracks" on a disc. This command is not fully implemented in the 1770 disc
interface and is not used by either DFS. Because it is not used by the DFS
it can be used for copy-protecting discs when the DFS *BACKUP command will
give the "disc fault" error. Copy-protection will be covered in detail in
module 6.
Two bad track registers are available for each disc surface and they are
used to specify which tracks are to be totally ignored by the 8271. For
example, if track 1 is bad the 8271 will use track 3 when track 2 is
specified. As far as the disc controller is concerned physical track 3 is
seen as physical track 2, physical track 4 is seen as physical track 3,
and so on.
When bad tracks are used their track number IDs should be set to &FF when
the disc is formatted. Track 0 must not be set as a bad track. The command
lasts until a hard reset.
The following parameter block is used by Osword &7F Load Bad Tracks.
Parameter block &00 = drive number (&00-&03 or &FF)
Parameter block &01 - &04 = buffer address (not used)
Parameter block &05 = &04 (4 command parameters)
Parameter block &06 = &75 (load bad tracks command)
Parameter block &07 = drive pair (&10 = drive 0/2, &18 = drive 1/3)
Parameter block &08 = bad track number 1
Parameter block &09 = bad track number 2
Parameter block &0A = current physical track
Parameter block &0B = result byte
The following code could be used to load bad tracks 1 and 2. Osword &7F
Seek command is used to position the head over a known physical track, in
this case track zero.
JSR seekzero \ seek track zero
LDA #&7F
LDX #block MOD 256
LDY #block DIV 256
JSR &FFF1
RTS
.block
EQUB &00 \ drive 0
EQUD &00 \ buffer address (not used)
EQUB &04 \ 4 parameters
EQUB &75 \ load bad tracks command
EQUB &10 \ drive 0/2
EQUB &01 \ track 1
EQUB &02 \ track 2
EQUB &00 \ current track
EQUB &00 \ result byte
---------------------------------
Osword &7F Write Special Register
---------------------------------
The internal registers of the 8271 can be overwritten using the Osword &7F
Write Special Register command. The contents of all the registers in
figure 4 can be altered but you are advised to limit yourself to altering
the track registers, numbers &12 and &1A. The bad track registers have
their own Osword &7F Load Bad Tracks command described above but they can
also be altered with the Osword &7F Write Special Register command. If you
decide to alter any other registers the results are likely to be
disasterous - you have been warned!
+--------------+---------------------------------+
| Register no. | Register |
+--------------+---------------------------------+
| &06 | Scan sector register |
| &10 | Bad track register 1, drive 0/2 |
| &11 | Bad track register 2, drive 0/2 |
| &12 | Track register, drive 0/2 |
| &13 | Scan count register (LSB) |
| &14 | Scan count register (MSB) |
| &17 | DMA mode register |
| &18 | Bad track register 1, drive 1/3 |
| &19 | Bad track register 2, drive 1/3 |
| &1A | Track register, drive 1/3 |
| &22 | Drive control input register |
| &23 | Drive control output register |
+--------------+---------------------------------+
Figure 4. The 8271 registers
----------------------------
The following parameter block must be used with the Osword &7F Write
Special Register command.
Parameter block &00 = drive number (&00-&03 or &FF)
Parameter block &01 - &04 = buffer address (not used)
Parameter block &05 = &02 (2 command parameters)
Parameter block &06 = &7A (write special register command)
Parameter block &07 = register number (from figure 4)
Parameter block &08 = value to put in register
Parameter block &09 = result byte
The track registers &12 (drive 0/2) and &1A (drive 1/3) are used by the
disc controller to identify its current track position. These registers
contain the number of the physical track. If the logical track number
stored in the sector ID is not the same as the physical track number you
should always use the write special register command to store the logical
track number in the track register before attempting to read from or write
to the disc. You must always reset the track register to its original
value after reading or writing. As you have seen in the module 0, using
different logical and physical track numbers is yet another technique for
copy-protecting discs.
The following code could be used to seek track 0 and then load the track
register for drive 0/2 with the number 1. Track zero will then be seen as
physical track 1.
JSR seekzero \ seek track zero
LDA #&7F
LDX #block MOD 256
LDY #block DIV 256
JSR &FFF1
RTS
.block
EQUB &00 \ drive 0
EQUD &00 \ buffer address (not used)
EQUB &02 \ 2 parameters
EQUB &7A \ write special register command
EQUB &12 \ track register drive 0/2
EQUB &01 \ track 1
EQUB &00 \ result byte
--------------------------------
Osword &7F Read Special Register
--------------------------------
The internal registers of the 8271 can be read using Osword &7F Read
Special Register. The contents of all the registers in figure 4 can be
read but not all the registers give useful results. The drive control
input register can be read using Osword &7F Read Drive Status command but
the drive control output register, and all the other registers, have to be
read with the Osword &7F Read Special Register command.
The following parameter block must be used with the Osword &7F Read Special
Register command.
Parameter block &00 = drive number (&00-&03 or &FF)
Parameter block &01 - &04 = buffer address (not used)
Parameter block &05 = &01 (1 command parameter)
Parameter block &06 = &7D (read special register command)
Parameter block &07 = register number (from figure 4)
Parameter block &08 = result byte
The program OUTPUT demonstrates how to read the contents of the drive
control output register for the current drive. The result is printed in
hexadecimal and binary. Each bit of the result has the following meaning:
bit 7 = SELECT 1
bit 6 = SELECT 0
bit 5 = FAULT RESET?OP0
bit 4 = LOW CURRENT
bit 3 = LOAD HEAD
bit 2 = DIRECTION
bit 1 = SEEK/STEP
bit 0 = WR ENABLE
It is interesting to run the program OUTPUT with drive 0 selected (using
*DRIVE 0) and then select drive 1 (with *DRIVE 1) and run the program
again to see the difference it makes to the result. If you want to read
any other register change the value &23 in line 180 for another register
number taken from figure 4.
10 REM: OUTPUT
20 oswrch=&FFEE
30 osword=&FFF1
40 DIM mcode &100
50 FOR pass = 0 TO 2 STEP 2
60 P%=mcode
70 [ OPT pass
80 LDA #&7F
90 LDX #block MOD 256
100 LDY #block DIV 256
110 JSR osword
120 RTS
130 .block
140 EQUB &FF \ current drive
150 EQUD &00 \ does not matter
160 EQUB &01 \ 1 parameter
170 EQUB &7D \ read special register command
180 EQUB &23 \ drive control output register
190 .result
200 EQUB &00 \ result byte
210 .binary
220 LDX #8
230 .loop
240 LDA #ASC("0")
250 ASL result
260 ADC #&00
270 JSR oswrch
280 DEX
290 BNE loop
300 RTS
310 ]
320 NEXT
330 CALL mcode
340 PRINT"Result = &";~?result;", %";
350 CALL binary
360 PRINT
00000000 54 68 65 20 41 63 6f 72 6e 20 44 46 53 20 4f 73 |The Acorn DFS Os|
00000010 77 6f 72 64 20 63 6f 6d 6d 61 6e 64 73 20 20 2d |word commands -|
00000020 20 20 62 79 20 20 2d 20 20 47 6f 72 64 6f 6e 20 | by - Gordon |
00000030 48 6f 72 73 69 6e 67 74 6f 6e 0d 2d 2d 2d 2d 2d |Horsington.-----|
00000040 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00000070 2d 2d 2d 2d 2d 0d 0d 4d 6f 64 75 6c 65 20 31 2e |-----..Module 1.|
00000080 20 54 68 65 20 44 46 53 20 4f 73 77 6f 72 64 20 | The DFS Osword |
00000090 63 6f 6d 6d 61 6e 64 73 20 28 70 61 72 74 20 31 |commands (part 1|
000000a0 29 0d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |).--------------|
000000b0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
000000c0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0d 0d 20 20 |------------.. |
000000d0 20 20 20 20 2b 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d | +-----------|
000000e0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00000100 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b |---------------+|
00000110 0d 20 20 20 20 20 20 7c 20 41 6c 6c 20 74 68 65 |. | All the|
00000120 20 44 46 53 20 6d 6f 64 75 6c 65 73 20 69 6e 20 | DFS modules in |
00000130 20 74 68 69 73 20 20 73 65 72 69 65 73 20 20 75 | this series u|
00000140 73 65 20 70 72 6f 67 72 61 6d 73 20 77 68 69 63 |se programs whic|
00000150 68 20 7c 0d 20 20 20 20 20 20 7c 20 65 78 70 65 |h |. | expe|
00000160 72 69 6d 65 6e 74 20 20 77 69 74 68 20 74 68 65 |riment with the|
00000170 20 66 6f 72 6d 61 74 20 61 6e 64 20 63 6f 6e 74 | format and cont|
00000180 65 6e 74 73 20 6f 66 20 64 69 73 63 73 2e 20 54 |ents of discs. T|
00000190 68 65 73 65 20 7c 0d 20 20 20 20 20 20 7c 20 65 |hese |. | e|
000001a0 78 70 65 72 69 6d 65 6e 74 73 20 6d 61 79 20 20 |xperiments may |
000001b0 68 61 76 65 20 64 69 73 61 73 74 65 72 6f 75 73 |have disasterous|
000001c0 20 65 66 66 65 63 74 73 20 69 66 20 79 6f 75 20 | effects if you |
000001d0 75 73 65 20 61 6e 79 20 7c 0d 20 20 20 20 20 20 |use any |. |
000001e0 7c 20 6f 66 20 74 68 65 20 70 72 6f 67 72 61 6d || of the program|
000001f0 73 20 20 6f 6e 20 20 64 69 73 63 73 20 20 77 68 |s on discs wh|
00000200 69 63 68 20 73 74 6f 72 65 20 70 72 6f 67 72 61 |ich store progra|
00000210 6d 73 20 6f 72 20 64 61 74 61 20 7c 0d 20 20 20 |ms or data |. |
00000220 20 20 20 7c 20 77 68 69 63 68 20 79 6f 75 20 63 | | which you c|
00000230 61 6e 6e 6f 74 20 61 66 66 6f 72 64 20 74 6f 20 |annot afford to |
00000240 6c 6f 73 65 2e 20 20 59 6f 75 20 20 73 68 6f 75 |lose. You shou|
00000250 6c 64 20 20 66 69 72 73 74 20 74 72 79 20 7c 0d |ld first try |.|
00000260 20 20 20 20 20 20 7c 20 6f 75 74 20 20 74 68 65 | | out the|
00000270 20 20 70 72 6f 67 72 61 6d 73 20 20 75 73 69 6e | programs usin|
00000280 67 20 20 64 69 73 63 73 20 20 74 68 61 74 20 20 |g discs that |
00000290 68 61 76 65 20 65 69 74 68 65 72 20 62 65 65 6e |have either been|
000002a0 20 7c 0d 20 20 20 20 20 20 7c 20 64 75 70 6c 69 | |. | dupli|
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*
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000054b0 73 74 65 72 20 20 20 20 7c 0d 20 20 20 20 20 20 |ster |. |
000054c0 20 20 7c 20 20 20 20 20 26 32 33 20 20 20 20 20 | | &23 |
000054d0 20 7c 20 44 72 69 76 65 20 63 6f 6e 74 72 6f 6c | | Drive control|
000054e0 20 6f 75 74 70 75 74 20 72 65 67 69 73 74 65 72 | output register|
000054f0 20 20 20 7c 0d 20 20 20 20 20 20 20 20 2b 2d 2d | |. +--|
00005500 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 2d 2d 2d |------------+---|
00005510 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00005520 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2b 0d |--------------+.|
00005530 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. |
00005540 20 46 69 67 75 72 65 20 34 2e 20 54 68 65 20 38 | Figure 4. The 8|
00005550 32 37 31 20 72 65 67 69 73 74 65 72 73 0d 20 20 |271 registers. |
00005560 20 20 20 20 20 20 20 20 20 20 20 20 20 20 2d 2d | --|
00005570 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
00005580 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0d 0d 0d 54 68 65 |----------...The|
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000055a0 65 74 65 72 20 62 6c 6f 63 6b 20 6d 75 73 74 20 |eter block must |
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000056a0 6f 63 6b 20 26 30 36 20 20 20 20 20 20 20 3d 20 |ock &06 = |
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000056e0 6c 6f 63 6b 20 26 30 37 20 20 20 20 20 20 20 3d |lock &07 =|
000056f0 20 72 65 67 69 73 74 65 72 20 6e 75 6d 62 65 72 | register number|
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00005720 20 26 30 38 20 20 20 20 20 20 20 3d 20 76 61 6c | &08 = val|
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00005750 62 6c 6f 63 6b 20 26 30 39 20 20 20 20 20 20 20 |block &09 |
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00006420 20 20 20 45 51 55 42 20 26 46 46 20 20 20 20 20 | EQUB &FF |
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000064e0 20 20 20 45 51 55 42 20 26 32 33 20 20 20 20 20 | EQUB &23 |
000064f0 20 5c 20 64 72 69 76 65 20 63 6f 6e 74 72 6f 6c | \ drive control|
00006500 20 6f 75 74 70 75 74 20 72 65 67 69 73 74 65 72 | output register|
00006510 0d 20 20 31 39 30 20 2e 72 65 73 75 6c 74 0d 20 |. 190 .result. |
00006520 20 32 30 30 20 20 20 20 20 20 20 20 20 45 51 55 | 200 EQU|
00006530 42 20 26 30 30 20 20 20 20 20 20 5c 20 72 65 73 |B &00 \ res|
00006540 75 6c 74 20 62 79 74 65 0d 20 20 32 31 30 20 2e |ult byte. 210 .|
00006550 62 69 6e 61 72 79 0d 20 20 32 32 30 20 20 20 20 |binary. 220 |
00006560 20 20 20 20 20 4c 44 58 20 23 38 0d 20 20 32 33 | LDX #8. 23|
00006570 30 20 2e 6c 6f 6f 70 0d 20 20 32 34 30 20 20 20 |0 .loop. 240 |
00006580 20 20 20 20 20 20 4c 44 41 20 23 41 53 43 28 22 | LDA #ASC("|
00006590 30 22 29 0d 20 20 32 35 30 20 20 20 20 20 20 20 |0"). 250 |
000065a0 20 20 41 53 4c 20 72 65 73 75 6c 74 0d 20 20 32 | ASL result. 2|
000065b0 36 30 20 20 20 20 20 20 20 20 20 41 44 43 20 23 |60 ADC #|
000065c0 26 30 30 0d 20 20 32 37 30 20 20 20 20 20 20 20 |&00. 270 |
000065d0 20 20 4a 53 52 20 6f 73 77 72 63 68 0d 20 20 32 | JSR oswrch. 2|
000065e0 38 30 20 20 20 20 20 20 20 20 20 44 45 58 0d 20 |80 DEX. |
000065f0 20 32 39 30 20 20 20 20 20 20 20 20 20 42 4e 45 | 290 BNE|
00006600 20 6c 6f 6f 70 0d 20 20 33 30 30 20 20 20 20 20 | loop. 300 |
00006610 20 20 20 20 52 54 53 0d 20 20 33 31 30 20 5d 0d | RTS. 310 ].|
00006620 20 20 33 32 30 20 4e 45 58 54 0d 20 20 33 33 30 | 320 NEXT. 330|
00006630 20 43 41 4c 4c 20 6d 63 6f 64 65 0d 20 20 33 34 | CALL mcode. 34|
00006640 30 20 50 52 49 4e 54 22 52 65 73 75 6c 74 20 3d |0 PRINT"Result =|
00006650 20 26 22 3b 7e 3f 72 65 73 75 6c 74 3b 22 2c 20 | &";~?result;", |
00006660 25 22 3b 0d 20 20 33 35 30 20 43 41 4c 4c 20 62 |%";. 350 CALL b|
00006670 69 6e 61 72 79 0d 20 20 33 36 30 20 50 52 49 4e |inary. 360 PRIN|
00006680 54 0d |T.|
00006682 
13-08-88/T\DFS01.m0
13-08-88/T\DFS01.m1
13-08-88/T\DFS01.m2
13-08-88/T\DFS01.m4
13-08-88/T\DFS01.m5
.