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06_11_87/T\SWR03
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 » telesoftware3.adl |
| Filename: | 06_11_87/T\SWR03 |
| Read OK: | ✔ |
| File size: | 2D97 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
Duplicates
There is 1 duplicate copy of this file in the archive:
- CEEFAX disks » telesoftware3.adl » 06_11_87/T\SWR03
- CEEFAX disks » telesoftware8.adl » 22-07-88/T\SWR03
File contents
Mastering Sideways ROM & RAM - Module 03 - One-command interpreter
------------------------------------------------------------------
In module 2 you were introduced to service calls, rom headers and
interpreters. In this module I will show how to trap a service call
and create an interpreter to recognise a new * command.
If you type a command, such as *SILLY, which is not recognised by
the MOS, the command is first offered to the sideways roms and then to
the currently active filing system.
Load the object code generated by the program TRACE into sideways
ram and press the Break key. You will see the now familiar service
call trace first used in module 2. Type a few * commands that the MOS
will not recognise. Try *SILLY if you can't think of anything better.
You will see the trace shown in figure 3.1. The MOS offers the command
to the sideways roms using service call 4, Unrecognised Command. The
NMI claim is used by the DFS and the Break service call is offered to
all the roms before the "bad command" error message is printed by
BASIC.
>*SILLY
A=04 X=0F Y=01 Unrecognised command
A=0C X=0F Y=FF NMI claim
A=06 X=0F Y=00 Break
Bad command
>
Figure 3.1 Service trace for unrecognised command.
--------------------------------------------------
When the unrecognised command service call is issued the roms are
entered at the service entry point. &F2 and &F3 are used as text
pointers to the command with an offset in the Y register pointing past
the asterisk and any leading spaces. Try typing a few spaces after the
asterisk and before the ASCII string of your command and watch the
effect on the Y register in the trace. &F2 and &F3 point to the
unrecognised command in the form of an ASCII string terminated by &0D.
The interpreter has to use the text pointers and the Y register to
compare every byte of the unrecognised command with every byte of your
new command. If every pair of bytes is identical then the command is
recognised and your new routine can be executed. If it is not
recognised your rom image must return control to the MOS with all the
registers preserved.
A simple one-command interpreter can compare the title string in the
header with the unrecognised command. You must choose the title string
with care. It must only use upper case alphabetic characters (because
the command will be forced to upper case by ANDing every character
with #&DF) and it must not conflict with any other * commands used in
your computer. You cannot use titles such as "SAVE" or "INFO" for
obvious reasons but you should also beware of title strings such as
"DESELECT" or "DRAW" which, if they are compared with the shortened
commands *DES. and *DR., will conflict with DESTROY and DRIVE.
Figure 3.2 illustrates one method of making the comparison and
jumping to a new routine when the unrecognised command matches the
title string. It uses absolute indexed addressing with the X register
and post-indexed indirect addressing with the Y register to compare
every byte of the title string with every byte of the unrecognised
command. The service entry point of the rom image in figure 3.2 has a
jump to the label ".service" which is the begining of the interpreter.
.title
EQUS "SILLY" \ title string in the header.
BRK \ first byte of copyright string.
.
.
.
.service
CMP #4 \ is it an unrecognised command?
BEQ unrecognised \ branch if it is
RTS \ return to MOS if it is not
.unrecognised
PHA \ push A
TXA
PHA \ push X
TYA
PHA \ push Y
LDX #&FF \ initialise X
.comloop
INX \ increment offset on title string
LDA title,X \ check if last byte of title.
BEQ found \ branch if last byte of title.
LDA (&F2),Y \ read next character of command.
INY \ increment offset to next character
CMP #ASC(".") \ is the character read a "."?
BEQ found \ branch if it is a shortened command.
AND #&DF \ force upper case.
CMP title,X \ is it the same as the title character?
BEQ comloop \ if it is compare next character
PLA \ if not pull Y
TAY \ restore Y
PLA \ pull X
TAX \ restore X
PLA \ restore A
RTS \ and return to MOS.
.found
. \ your new routine
. \ goes in here
.
PLA \ pull Y and discard
PLA \ pull X and discard
PLA \ pull A and discard
LDA #0 \ other roms ignore this request.
RTS \ return to MOS
Figure 3.2 An unrecognised * command interpreter.
-------------------------------------------------
The trace program has shown you that, when an unrecognised * command
is passed to the sideways roms, each rom is entered at the service
entry point with the accumulator = 4, the X register = the number of
the rom, and the Y register = the offset to the unrecognised command.
The interpreter compares the accumulator with 4 to see if it is an
unrecognised command. If it is control is passed to the label
".unrecognised", if it is not control is returned to the MOS with the
A, X, and Y registers all unaltered.
Before comparing the unrecognised command with the title string of
the rom, the A, X and Y registers are pushed on the stack so that they
can be restored if the unrecognised command is not identical to the
title string. After pushing the registers every byte of the title
string is compared with every byte of the unrecognised command. If the
comparison fails before every byte has been compared the registers are
restored and control is returned to the MOS.
There are two conditions when the command is recognised by the
interpreter.
1. If every byte of the unrecognised command is identical to every
byte of the title string the interpreter will eventually read the zero
byte at the end of the title.
2. If every byte of the title string is identical to every byte of the
unrecognised command until a "." terminates the unrecognised command.
When the unrecognised command has been recognised by the interpreter
control is passed to the label ".found" which will be the beginning of
any new routine you care to use. When your new routine has finished
the Y, X and A registers pushed onto the stack by the interpreter must
be pulled off and discarded. Your program must pull the Y, X and A
registers off the stack but there is no need to transfer A to Y and X
with the first two pulls because the index registers will be ignored
when you return with A=0. After the third PLA, your program must load
the accumulator with zero before returning to the MOS. This will
inform all other roms that the service request has been recognised.
This simple interpreter has been used to convert the program ZAP
into its sideways ram equivalent NEWCOM.
In the program ZAP the Assembly language coding from line 70 to line
230 is the equivalent of the BASIC ENVELOPE and SOUND commands. The
program uses Osword 8 with a 14 byte parameter block (which
corresponds with the 14 parameters in the ENVELOPE command) and Osword
7 with an 8 byte parameter block (which corresponds with the 4
parameters in the sound command). Line 270 executes the machine code
generated by the Assembly language coding. When the program has been
converted into sideways ram format and loaded into sideways ram the
entire program can be replaced with the new command *ZAP.
10 REM: ZAP
20 DIM mcode 100
30 osword=&FFF1
40 FOR pass = 0 TO 2 STEP 2
50 P%=mcode
60 [ OPT pass
70 LDA #8
80 LDX #envelope MOD 256
90 LDY #envelope DIV 256
100 JSR osword
110 LDA #7
120 LDX #sound MOD 256
130 LDY #sound DIV 256
140 JSR osword
150 RTS
160 .envelope
170 OPT FNequd(&7FFC0101)
180 OPT FNequd(&8D65830A)
190 OPT FNequd(&8100FF7F)
200 OPT FNequw(&7E7E)
210 .sound
220 OPT FNequd(&00010011)
230 OPT FNequd(&00640000)
240 .lastbyte
250 ]
260 NEXT
270 CALL mcode
280 END
290 DEFFNequw(word)
300 ?P%=word MOD 256
310 P%?1=word DIV 256
320 P%=P%+2
330 =pass
340 DEFFNequd(double)
350 !P%=double
360 P%=P%+4
370 =pass
The program NEWCOM illustrates the conversion into sideways ram
format using the simple one-command interpreter described above. The
rom type byte in line 170 of NEWCOM indicates to the MOS that the rom
image has a service entry. The interpreter (lines 270-530) compares
the unrecognised command with the title string and if they match
contol is passed to the label ".found" in line 540. The code taken
from the program ZAP is inserted after the label ".found" in NEWCOM
but the RTS instruction in line 150 of ZAP has been replaced with PLA
: PLA : PLA : LDA #0 : RTS in lines 630 to 670 of NEWCOM in order to
balance the stack and load the accumulator with zero before returning
control to the MOS.
10 REM: NEWCOM
20 MODE7
30 HIMEM=&3C00
40 DIM save 50
50 diff=&8000-HIMEM
60 comvec=&F2
70 gsread=&FFC5
80 osword=&FFF1
90 oscli=&FFF7
100 FOR pass = 0 TO 2 STEP 2
110 P%=HIMEM
120 [ OPT pass
130 BRK
140 BRK
150 BRK
160 JMP service+diff
170 OPT FNequb(&82)
180 OPT FNequb((copyright+diff) MOD 256)
190 BRK
200 .title
210 OPT FNequs("ZAP")
220 .copyright
230 BRK
240 OPT FNequs("(C) Gordon Horsington 1987")
250 BRK
260 .service
270 CMP #4
280 BEQ unrecognised
290 RTS
300 .unrecognised
310 PHA
320 TXA
330 PHA
340 TYA
350 PHA
360 LDX #&FF
370 .comloop
380 INX
390 LDA title+diff,X
400 BEQ found
410 LDA (comvec),Y
420 INY
430 CMP #ASC(".")
440 BEQ found
450 AND #&DF
460 CMP title+diff,X
470 BEQ comloop
480 PLA
490 TAY
500 PLA
510 TAX
520 PLA
530 RTS
540 .found
550 LDA #8
560 LDX #((envelope+diff) MOD 256)
570 LDY #((envelope+diff) DIV 256)
580 JSR osword
590 LDA #7
600 LDX #((sound+diff) MOD 256)
610 LDY #((sound+diff) DIV 256)
620 JSR osword
630 PLA
640 PLA
650 PLA
660 LDA #0
670 RTS
680 .envelope
690 OPT FNequd(&7FFC0101)
700 OPT FNequd(&8D65830A)
710 OPT FNequd(&8100FF7F)
720 OPT FNequw(&7E7E)
730 .sound
740 OPT FNequd(&00010011)
750 OPT FNequd(&00640000)
760 .lastbyte
770 ]
780 NEXT
790 INPUT'"Save filename = "filename$
800 IF filename$="" END
810 $save="SAVE "+filename$+" "+STR$~(HIMEM)+" "+STR$~(las
tbyte)+" FFFF8000 FFFF8000"
820 X%=save MOD 256
830 Y%=save DIV 256
840 *OPT1,2
850 CALL oscli
860 *OPT1,0
870 END
880 DEFFNequb(byte)
890 ?P%=byte
900 P%=P%+1
910 =pass
920 DEFFNequw(word)
930 ?P%=word MOD 256
940 P%?1=word DIV 256
950 P%=P%+2
960 =pass
970 DEFFNequd(double)
980 !P%=double
990 P%=P%+4
1000 =pass
1010 DEFFNequs(string$)
1020 $P%=string$
1030 P%=P%+LEN(string$)
1040 =pass
00000000 4d 61 73 74 65 72 69 6e 67 20 53 69 64 65 77 61 |Mastering Sidewa|
00000010 79 73 20 52 4f 4d 20 26 20 52 41 4d 20 2d 20 4d |ys ROM & RAM - M|
00000020 6f 64 75 6c 65 20 30 33 20 2d 20 4f 6e 65 2d 63 |odule 03 - One-c|
00000030 6f 6d 6d 61 6e 64 20 69 6e 74 65 72 70 72 65 74 |ommand interpret|
00000040 65 72 0d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |er.-------------|
00000050 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00000080 2d 2d 2d 2d 2d 0d 0d 20 20 49 6e 20 6d 6f 64 75 |-----.. In modu|
00000090 6c 65 20 32 20 79 6f 75 20 77 65 72 65 20 69 6e |le 2 you were in|
000000a0 74 72 6f 64 75 63 65 64 20 74 6f 20 73 65 72 76 |troduced to serv|
000000b0 69 63 65 20 63 61 6c 6c 73 2c 20 72 6f 6d 20 68 |ice calls, rom h|
000000c0 65 61 64 65 72 73 20 61 6e 64 0d 69 6e 74 65 72 |eaders and.inter|
000000d0 70 72 65 74 65 72 73 2e 20 49 6e 20 74 68 69 73 |preters. In this|
000000e0 20 6d 6f 64 75 6c 65 20 49 20 77 69 6c 6c 20 73 | module I will s|
000000f0 68 6f 77 20 68 6f 77 20 74 6f 20 74 72 61 70 20 |how how to trap |
00000100 61 20 73 65 72 76 69 63 65 20 63 61 6c 6c 0d 61 |a service call.a|
00000110 6e 64 20 63 72 65 61 74 65 20 61 6e 20 69 6e 74 |nd create an int|
00000120 65 72 70 72 65 74 65 72 20 74 6f 20 72 65 63 6f |erpreter to reco|
00000130 67 6e 69 73 65 20 61 20 6e 65 77 20 2a 20 63 6f |gnise a new * co|
00000140 6d 6d 61 6e 64 2e 0d 0d 20 20 49 66 20 79 6f 75 |mmand... If you|
00000150 20 74 79 70 65 20 61 20 63 6f 6d 6d 61 6e 64 2c | type a command,|
00000160 20 73 75 63 68 20 61 73 20 2a 53 49 4c 4c 59 2c | such as *SILLY,|
00000170 20 77 68 69 63 68 20 69 73 20 6e 6f 74 20 72 65 | which is not re|
00000180 63 6f 67 6e 69 73 65 64 20 62 79 0d 74 68 65 20 |cognised by.the |
00000190 4d 4f 53 2c 20 74 68 65 20 63 6f 6d 6d 61 6e 64 |MOS, the command|
000001a0 20 69 73 20 66 69 72 73 74 20 6f 66 66 65 72 65 | is first offere|
000001b0 64 20 74 6f 20 74 68 65 20 73 69 64 65 77 61 79 |d to the sideway|
000001c0 73 20 72 6f 6d 73 20 61 6e 64 20 74 68 65 6e 20 |s roms and then |
000001d0 74 6f 0d 74 68 65 20 63 75 72 72 65 6e 74 6c 79 |to.the currently|
000001e0 20 61 63 74 69 76 65 20 66 69 6c 69 6e 67 20 73 | active filing s|
000001f0 79 73 74 65 6d 2e 0d 0d 20 20 4c 6f 61 64 20 74 |ystem... Load t|
00000200 68 65 20 6f 62 6a 65 63 74 20 63 6f 64 65 20 67 |he object code g|
00000210 65 6e 65 72 61 74 65 64 20 62 79 20 74 68 65 20 |enerated by the |
00000220 70 72 6f 67 72 61 6d 20 54 52 41 43 45 20 69 6e |program TRACE in|
00000230 74 6f 20 73 69 64 65 77 61 79 73 0d 72 61 6d 20 |to sideways.ram |
00000240 61 6e 64 20 70 72 65 73 73 20 74 68 65 20 42 72 |and press the Br|
00000250 65 61 6b 20 6b 65 79 2e 20 59 6f 75 20 77 69 6c |eak key. You wil|
00000260 6c 20 73 65 65 20 74 68 65 20 6e 6f 77 20 66 61 |l see the now fa|
00000270 6d 69 6c 69 61 72 20 73 65 72 76 69 63 65 0d 63 |miliar service.c|
00000280 61 6c 6c 20 74 72 61 63 65 20 66 69 72 73 74 20 |all trace first |
00000290 75 73 65 64 20 69 6e 20 6d 6f 64 75 6c 65 20 32 |used in module 2|
000002a0 2e 20 54 79 70 65 20 61 20 66 65 77 20 2a 20 63 |. Type a few * c|
000002b0 6f 6d 6d 61 6e 64 73 20 74 68 61 74 20 74 68 65 |ommands that the|
000002c0 20 4d 4f 53 0d 77 69 6c 6c 20 6e 6f 74 20 72 65 | MOS.will not re|
000002d0 63 6f 67 6e 69 73 65 2e 20 54 72 79 20 2a 53 49 |cognise. Try *SI|
000002e0 4c 4c 59 20 69 66 20 79 6f 75 20 63 61 6e 27 74 |LLY if you can't|
000002f0 20 74 68 69 6e 6b 20 6f 66 20 61 6e 79 74 68 69 | think of anythi|
00000300 6e 67 20 62 65 74 74 65 72 2e 0d 59 6f 75 20 77 |ng better..You w|
00000310 69 6c 6c 20 73 65 65 20 74 68 65 20 74 72 61 63 |ill see the trac|
00000320 65 20 73 68 6f 77 6e 20 69 6e 20 66 69 67 75 72 |e shown in figur|
00000330 65 20 33 2e 31 2e 20 54 68 65 20 4d 4f 53 20 6f |e 3.1. The MOS o|
00000340 66 66 65 72 73 20 74 68 65 20 63 6f 6d 6d 61 6e |ffers the comman|
00000350 64 0d 74 6f 20 74 68 65 20 73 69 64 65 77 61 79 |d.to the sideway|
00000360 73 20 72 6f 6d 73 20 75 73 69 6e 67 20 73 65 72 |s roms using ser|
00000370 76 69 63 65 20 63 61 6c 6c 20 34 2c 20 55 6e 72 |vice call 4, Unr|
00000380 65 63 6f 67 6e 69 73 65 64 20 43 6f 6d 6d 61 6e |ecognised Comman|
00000390 64 2e 20 54 68 65 0d 4e 4d 49 20 63 6c 61 69 6d |d. The.NMI claim|
000003a0 20 69 73 20 75 73 65 64 20 62 79 20 74 68 65 20 | is used by the |
000003b0 44 46 53 20 61 6e 64 20 74 68 65 20 42 72 65 61 |DFS and the Brea|
000003c0 6b 20 73 65 72 76 69 63 65 20 63 61 6c 6c 20 69 |k service call i|
000003d0 73 20 6f 66 66 65 72 65 64 20 74 6f 0d 61 6c 6c |s offered to.all|
000003e0 20 74 68 65 20 72 6f 6d 73 20 62 65 66 6f 72 65 | the roms before|
000003f0 20 74 68 65 20 22 62 61 64 20 63 6f 6d 6d 61 6e | the "bad comman|
00000400 64 22 20 65 72 72 6f 72 20 6d 65 73 73 61 67 65 |d" error message|
00000410 20 69 73 20 70 72 69 6e 74 65 64 20 62 79 0d 42 | is printed by.B|
00000420 41 53 49 43 2e 0d 0d 0d 0d 3e 2a 53 49 4c 4c 59 |ASIC.....>*SILLY|
00000430 0d 20 41 3d 30 34 20 58 3d 30 46 20 59 3d 30 31 |. A=04 X=0F Y=01|
00000440 20 55 6e 72 65 63 6f 67 6e 69 73 65 64 20 63 6f | Unrecognised co|
00000450 6d 6d 61 6e 64 0d 20 41 3d 30 43 20 58 3d 30 46 |mmand. A=0C X=0F|
00000460 20 59 3d 46 46 20 4e 4d 49 20 63 6c 61 69 6d 0d | Y=FF NMI claim.|
00000470 20 41 3d 30 36 20 58 3d 30 46 20 59 3d 30 30 20 | A=06 X=0F Y=00 |
00000480 42 72 65 61 6b 0d 0d 42 61 64 20 63 6f 6d 6d 61 |Break..Bad comma|
00000490 6e 64 0d 3e 0d 0d 46 69 67 75 72 65 20 33 2e 31 |nd.>..Figure 3.1|
000004a0 20 53 65 72 76 69 63 65 20 74 72 61 63 65 20 66 | Service trace f|
000004b0 6f 72 20 75 6e 72 65 63 6f 67 6e 69 73 65 64 20 |or unrecognised |
000004c0 63 6f 6d 6d 61 6e 64 2e 0d 2d 2d 2d 2d 2d 2d 2d |command..-------|
000004d0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
000004f0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0d 0d 0d 0d 20 |-----------.... |
00000500 20 57 68 65 6e 20 74 68 65 20 75 6e 72 65 63 6f | When the unreco|
00000510 67 6e 69 73 65 64 20 63 6f 6d 6d 61 6e 64 20 73 |gnised command s|
00000520 65 72 76 69 63 65 20 63 61 6c 6c 20 69 73 20 69 |ervice call is i|
00000530 73 73 75 65 64 20 74 68 65 20 72 6f 6d 73 20 61 |ssued the roms a|
00000540 72 65 0d 65 6e 74 65 72 65 64 20 61 74 20 74 68 |re.entered at th|
00000550 65 20 73 65 72 76 69 63 65 20 65 6e 74 72 79 20 |e service entry |
00000560 70 6f 69 6e 74 2e 20 26 46 32 20 61 6e 64 20 26 |point. &F2 and &|
00000570 46 33 20 61 72 65 20 75 73 65 64 20 61 73 20 74 |F3 are used as t|
00000580 65 78 74 0d 70 6f 69 6e 74 65 72 73 20 74 6f 20 |ext.pointers to |
00000590 74 68 65 20 63 6f 6d 6d 61 6e 64 20 77 69 74 68 |the command with|
000005a0 20 61 6e 20 6f 66 66 73 65 74 20 69 6e 20 74 68 | an offset in th|
000005b0 65 20 59 20 72 65 67 69 73 74 65 72 20 70 6f 69 |e Y register poi|
000005c0 6e 74 69 6e 67 20 70 61 73 74 0d 74 68 65 20 61 |nting past.the a|
000005d0 73 74 65 72 69 73 6b 20 61 6e 64 20 61 6e 79 20 |sterisk and any |
000005e0 6c 65 61 64 69 6e 67 20 73 70 61 63 65 73 2e 20 |leading spaces. |
000005f0 54 72 79 20 74 79 70 69 6e 67 20 61 20 66 65 77 |Try typing a few|
00000600 20 73 70 61 63 65 73 20 61 66 74 65 72 20 74 68 | spaces after th|
00000610 65 0d 61 73 74 65 72 69 73 6b 20 61 6e 64 20 62 |e.asterisk and b|
00000620 65 66 6f 72 65 20 74 68 65 20 41 53 43 49 49 20 |efore the ASCII |
00000630 73 74 72 69 6e 67 20 6f 66 20 79 6f 75 72 20 63 |string of your c|
00000640 6f 6d 6d 61 6e 64 20 61 6e 64 20 77 61 74 63 68 |ommand and watch|
00000650 20 74 68 65 0d 65 66 66 65 63 74 20 6f 6e 20 74 | the.effect on t|
00000660 68 65 20 59 20 72 65 67 69 73 74 65 72 20 69 6e |he Y register in|
00000670 20 74 68 65 20 74 72 61 63 65 2e 20 26 46 32 20 | the trace. &F2 |
00000680 61 6e 64 20 26 46 33 20 70 6f 69 6e 74 20 74 6f |and &F3 point to|
00000690 20 74 68 65 0d 75 6e 72 65 63 6f 67 6e 69 73 65 | the.unrecognise|
000006a0 64 20 63 6f 6d 6d 61 6e 64 20 69 6e 20 74 68 65 |d command in the|
000006b0 20 66 6f 72 6d 20 6f 66 20 61 6e 20 41 53 43 49 | form of an ASCI|
000006c0 49 20 73 74 72 69 6e 67 20 74 65 72 6d 69 6e 61 |I string termina|
000006d0 74 65 64 20 62 79 20 26 30 44 2e 0d 54 68 65 20 |ted by &0D..The |
000006e0 69 6e 74 65 72 70 72 65 74 65 72 20 68 61 73 20 |interpreter has |
000006f0 74 6f 20 75 73 65 20 74 68 65 20 74 65 78 74 20 |to use the text |
00000700 70 6f 69 6e 74 65 72 73 20 61 6e 64 20 74 68 65 |pointers and the|
00000710 20 59 20 72 65 67 69 73 74 65 72 20 74 6f 0d 63 | Y register to.c|
00000720 6f 6d 70 61 72 65 20 65 76 65 72 79 20 62 79 74 |ompare every byt|
00000730 65 20 6f 66 20 74 68 65 20 75 6e 72 65 63 6f 67 |e of the unrecog|
00000740 6e 69 73 65 64 20 63 6f 6d 6d 61 6e 64 20 77 69 |nised command wi|
00000750 74 68 20 65 76 65 72 79 20 62 79 74 65 20 6f 66 |th every byte of|
00000760 20 79 6f 75 72 0d 6e 65 77 20 63 6f 6d 6d 61 6e | your.new comman|
00000770 64 2e 20 49 66 20 65 76 65 72 79 20 70 61 69 72 |d. If every pair|
00000780 20 6f 66 20 62 79 74 65 73 20 69 73 20 69 64 65 | of bytes is ide|
00000790 6e 74 69 63 61 6c 20 74 68 65 6e 20 74 68 65 20 |ntical then the |
000007a0 63 6f 6d 6d 61 6e 64 20 69 73 0d 72 65 63 6f 67 |command is.recog|
000007b0 6e 69 73 65 64 20 61 6e 64 20 79 6f 75 72 20 6e |nised and your n|
000007c0 65 77 20 72 6f 75 74 69 6e 65 20 63 61 6e 20 62 |ew routine can b|
000007d0 65 20 65 78 65 63 75 74 65 64 2e 20 49 66 20 69 |e executed. If i|
000007e0 74 20 69 73 20 6e 6f 74 0d 72 65 63 6f 67 6e 69 |t is not.recogni|
000007f0 73 65 64 20 79 6f 75 72 20 72 6f 6d 20 69 6d 61 |sed your rom ima|
00000800 67 65 20 6d 75 73 74 20 72 65 74 75 72 6e 20 63 |ge must return c|
00000810 6f 6e 74 72 6f 6c 20 74 6f 20 74 68 65 20 4d 4f |ontrol to the MO|
00000820 53 20 77 69 74 68 20 61 6c 6c 20 74 68 65 0d 72 |S with all the.r|
00000830 65 67 69 73 74 65 72 73 20 70 72 65 73 65 72 76 |egisters preserv|
00000840 65 64 2e 0d 0d 20 20 41 20 73 69 6d 70 6c 65 20 |ed... A simple |
00000850 6f 6e 65 2d 63 6f 6d 6d 61 6e 64 20 69 6e 74 65 |one-command inte|
00000860 72 70 72 65 74 65 72 20 63 61 6e 20 63 6f 6d 70 |rpreter can comp|
00000870 61 72 65 20 74 68 65 20 74 69 74 6c 65 20 73 74 |are the title st|
00000880 72 69 6e 67 20 69 6e 20 74 68 65 0d 68 65 61 64 |ring in the.head|
00000890 65 72 20 77 69 74 68 20 74 68 65 20 75 6e 72 65 |er with the unre|
000008a0 63 6f 67 6e 69 73 65 64 20 63 6f 6d 6d 61 6e 64 |cognised command|
000008b0 2e 20 59 6f 75 20 6d 75 73 74 20 63 68 6f 6f 73 |. You must choos|
000008c0 65 20 74 68 65 20 74 69 74 6c 65 20 73 74 72 69 |e the title stri|
000008d0 6e 67 0d 77 69 74 68 20 63 61 72 65 2e 20 49 74 |ng.with care. It|
000008e0 20 6d 75 73 74 20 6f 6e 6c 79 20 75 73 65 20 75 | must only use u|
000008f0 70 70 65 72 20 63 61 73 65 20 61 6c 70 68 61 62 |pper case alphab|
00000900 65 74 69 63 20 63 68 61 72 61 63 74 65 72 73 20 |etic characters |
00000910 28 62 65 63 61 75 73 65 0d 74 68 65 20 63 6f 6d |(because.the com|
00000920 6d 61 6e 64 20 77 69 6c 6c 20 62 65 20 66 6f 72 |mand will be for|
00000930 63 65 64 20 74 6f 20 75 70 70 65 72 20 63 61 73 |ced to upper cas|
00000940 65 20 62 79 20 41 4e 44 69 6e 67 20 65 76 65 72 |e by ANDing ever|
00000950 79 20 63 68 61 72 61 63 74 65 72 0d 77 69 74 68 |y character.with|
00000960 20 23 26 44 46 29 20 61 6e 64 20 69 74 20 6d 75 | #&DF) and it mu|
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00002ae0 75 77 28 26 37 45 37 45 29 0d 20 20 37 33 30 20 |uw(&7E7E). 730 |
00002af0 2e 73 6f 75 6e 64 0d 20 20 37 34 30 20 20 20 20 |.sound. 740 |
00002b00 20 20 20 20 20 4f 50 54 20 46 4e 65 71 75 64 28 | OPT FNequd(|
00002b10 26 30 30 30 31 30 30 31 31 29 0d 20 20 37 35 30 |&00010011). 750|
00002b20 20 20 20 20 20 20 20 20 20 4f 50 54 20 46 4e 65 | OPT FNe|
00002b30 71 75 64 28 26 30 30 36 34 30 30 30 30 29 0d 20 |qud(&00640000). |
00002b40 20 37 36 30 20 2e 6c 61 73 74 62 79 74 65 0d 20 | 760 .lastbyte. |
00002b50 20 37 37 30 20 5d 0d 20 20 37 38 30 20 4e 45 58 | 770 ]. 780 NEX|
00002b60 54 0d 20 20 37 39 30 20 49 4e 50 55 54 27 22 53 |T. 790 INPUT'"S|
00002b70 61 76 65 20 66 69 6c 65 6e 61 6d 65 20 3d 20 22 |ave filename = "|
00002b80 66 69 6c 65 6e 61 6d 65 24 0d 20 20 38 30 30 20 |filename$. 800 |
00002b90 49 46 20 66 69 6c 65 6e 61 6d 65 24 3d 22 22 20 |IF filename$="" |
00002ba0 45 4e 44 0d 20 20 38 31 30 20 24 73 61 76 65 3d |END. 810 $save=|
00002bb0 22 53 41 56 45 20 22 2b 66 69 6c 65 6e 61 6d 65 |"SAVE "+filename|
00002bc0 24 2b 22 20 22 2b 53 54 52 24 7e 28 48 49 4d 45 |$+" "+STR$~(HIME|
00002bd0 4d 29 2b 22 20 22 2b 53 54 52 24 7e 28 6c 61 73 |M)+" "+STR$~(las|
00002be0 0d 20 20 20 20 20 20 74 62 79 74 65 29 2b 22 20 |. tbyte)+" |
00002bf0 46 46 46 46 38 30 30 30 20 46 46 46 46 38 30 30 |FFFF8000 FFFF800|
00002c00 30 22 0d 20 20 38 32 30 20 58 25 3d 73 61 76 65 |0". 820 X%=save|
00002c10 20 4d 4f 44 20 32 35 36 0d 20 20 38 33 30 20 59 | MOD 256. 830 Y|
00002c20 25 3d 73 61 76 65 20 44 49 56 20 32 35 36 0d 20 |%=save DIV 256. |
00002c30 20 38 34 30 20 2a 4f 50 54 31 2c 32 0d 20 20 38 | 840 *OPT1,2. 8|
00002c40 35 30 20 43 41 4c 4c 20 6f 73 63 6c 69 0d 20 20 |50 CALL oscli. |
00002c50 38 36 30 20 2a 4f 50 54 31 2c 30 0d 20 20 38 37 |860 *OPT1,0. 87|
00002c60 30 20 45 4e 44 0d 20 20 38 38 30 20 44 45 46 46 |0 END. 880 DEFF|
00002c70 4e 65 71 75 62 28 62 79 74 65 29 0d 20 20 38 39 |Nequb(byte). 89|
00002c80 30 20 3f 50 25 3d 62 79 74 65 0d 20 20 39 30 30 |0 ?P%=byte. 900|
00002c90 20 50 25 3d 50 25 2b 31 0d 20 20 39 31 30 20 3d | P%=P%+1. 910 =|
00002ca0 70 61 73 73 0d 20 20 39 32 30 20 44 45 46 46 4e |pass. 920 DEFFN|
00002cb0 65 71 75 77 28 77 6f 72 64 29 0d 20 20 39 33 30 |equw(word). 930|
00002cc0 20 3f 50 25 3d 77 6f 72 64 20 4d 4f 44 20 32 35 | ?P%=word MOD 25|
00002cd0 36 0d 20 20 39 34 30 20 50 25 3f 31 3d 77 6f 72 |6. 940 P%?1=wor|
00002ce0 64 20 44 49 56 20 32 35 36 0d 20 20 39 35 30 20 |d DIV 256. 950 |
00002cf0 50 25 3d 50 25 2b 32 0d 20 20 39 36 30 20 3d 70 |P%=P%+2. 960 =p|
00002d00 61 73 73 0d 20 20 39 37 30 20 44 45 46 46 4e 65 |ass. 970 DEFFNe|
00002d10 71 75 64 28 64 6f 75 62 6c 65 29 0d 20 20 39 38 |qud(double). 98|
00002d20 30 20 21 50 25 3d 64 6f 75 62 6c 65 0d 20 20 39 |0 !P%=double. 9|
00002d30 39 30 20 50 25 3d 50 25 2b 34 0d 20 31 30 30 30 |90 P%=P%+4. 1000|
00002d40 20 3d 70 61 73 73 0d 20 31 30 31 30 20 44 45 46 | =pass. 1010 DEF|
00002d50 46 4e 65 71 75 73 28 73 74 72 69 6e 67 24 29 0d |FNequs(string$).|
00002d60 20 31 30 32 30 20 24 50 25 3d 73 74 72 69 6e 67 | 1020 $P%=string|
00002d70 24 0d 20 31 30 33 30 20 50 25 3d 50 25 2b 4c 45 |$. 1030 P%=P%+LE|
00002d80 4e 28 73 74 72 69 6e 67 24 29 0d 20 31 30 34 30 |N(string$). 1040|
00002d90 20 3d 70 61 73 73 0d | =pass.|
00002d97 
06_11_87/T\SWR03.m0
06_11_87/T\SWR03.m1
06_11_87/T\SWR03.m2
06_11_87/T\SWR03.m4
06_11_87/T\SWR03.m5
.