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20-02-88/T\SWR17
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 » telesoftware5.adl |
| Filename: | 20-02-88/T\SWR17 |
| Read OK: | ✔ |
| File size: | 3619 bytes |
| Load address: | 0000 |
| Exec address: | FFFFFFFF |
Duplicates
There is 1 duplicate copy of this file in the archive:
- CEEFAX disks » telesoftware10.adl » 29-10-88/T\SWR17
- CEEFAX disks » telesoftware5.adl » 20-02-88/T\SWR17
File contents
Mastering Sideways ROM & RAM - Module 17 - Language Roms
--------------------------------------------------------
The first 16 modules of this course have dealt almost exclusively
with the design of service roms. The rest of the course will be
dealing with the design of roms that use both language and service
entry points.
A new language does not need the complexity of a new dialect of
BASIC. It simply needs to be a self contained machine code program
which is totally independant of any other language. Language roms have
access to memory from &00 to &8F as zero page workspace, from &0400 to
&07FF as main language workspace and from Oshwm to the bottom of
screen memory as program space.
The program NOBASIC is a good example of an extremely simple
language. Unlike BASIC it has no keywords and only processes *
commands. It uses an Osword call to read input from the keyboard into
a buffer in page &07 and passes that input to the command line
interpreter (CLI) for further processing. The return from the CLI goes
back for more input which is passed to the CLI, and so on and on until
another language is selected to replace it. Although NOBASIC has no
keywords it meets all the requirements for a language. It is self
contained and completely independant of any other language.
To use the language load the object code generated by NOBASIC into
SWR and press the Break key. Type *NOBASIC and press Return. The
language title and a "*" prompt will be printed. The language will
only allow you to use operating system, filing system and service rom
commands. There is no need to type the * prefix for these commands.
If, for example, you want to return to BASIC just type BASIC.
When starting up a language the MOS does the following:
1. Records the number of the rom so that it can reselect the language
when a BRK instruction is executed and when the Break key is pressed
(a "soft" break).
2. Displays the rom title string to indicate the particular language
is in use.
3. Points the error message vector to the copyright message, or the
version string if present.
4. If a second processor is active, copies the language across the
Tube and executes it there. The service code is not copied across the
Tube.
5. Enters the language at its language entry point with the
accumulator containing the value &01 to indicate a normal startup.
As well as providing a language entry point, a language rom must
provide a service entry point which gives access to a simple one
command interpreter to recognise the language name as a command. Upon
recognising the language name the rom must load the X register with
its rom number and call Osbyte &8E to start up the language. Languages
other than BASIC can only be started up using Osbyte &8E with the rom
number of the language in the X register. The service entry point must
also provide a help service which responds to *HELP by printing the
language title string.
When a language rom is entered at its language entry point it must
do the following:
a. Enable interupts, otherwise the operating system will fail to work.
b. Reset the stack pointer. The stack is undefined on entry.
c. Set up the error handling routine.
Even a simple language such as NOBASIC requires error handling. The
operating system automatically switches to the current language rom on
a BRK. When a BRK occurs, the currently active rom number is stored
and can be read using Osbyte &BA. The NOBASIC error handler does not
use Osbyte &BA. It prints the error message pointed to by the error
vector and resets the language by jumping back to the language entry
point.
The rom header of a language rom has to be configured appropriately
in order that the MOS can recognise the rom image as a language rom.
The difference between service rom and language rom headers is that
the latter has a jump to the language entry point in the first three
bytes of the header and the rom type byte at &8006 usually stores the
number &C2 to indicate that language and service entry points are
available. The rom header for NOBASIC is shown in figure 17.1. Rom
headers were described in detail in Module 3 of the course. You may
need to look again at Module 3 if you have forgotten about rom headers
and rom type bytes.
8000 4C 82 80 JMP language \ jump to language entry point
8003 4C 2D 80 JMP service \ jump to service entry point
8006 C2 EQUB &C2 \ rom type bute (1100 0010)
8007 11 EQUB copyright MOD 256 \ copyright offset
8008 00 BRK \ binary version number (zero)
8009 .title \ rom title string
8009 4E 4F 42
41 53 49
43 EQUS "NOBASIC"
8010 00 BRK
8011 .copyright \ copyright string
8011 00 BRK \ must start with zero
8012 28 43 29
20 47 6F
72 64 6F
6E 20 48
6F 72 73
69 6E 67
74 6F 6E
20 31 39
38 37 EQUS "(C) Gordon Horsington 1987"
802C 00 BRK \ and end with zero
802D .service \ service entry point
.
.
.
8082 .language \ language entry point
.
.
.
Figure 17.1 The NOBASIC rom header.
----------- -----------------------
The service entry point of NOBASIC gives access to an unrecognised *
command interpreter and a simple help service. The registers are
pushed on the stack (lines 350-390). The original content of the
accumulator is read from the stack (lines 400-410) and compared with
the unrecognised command and help service request numbers (lines
420-450). If neither service call 4 nor service call 9 is intercepted
the registers are restored (lines 470-510) and control is returned to
the MOS (line 520).
The familiar one command interpreter (lines 530-660) is used to
compare the unrecognised command with the title string of the rom. If
a match is found control passes to the label ".found" (line 670). If
it is not the registers are restored (line 660 and lines 470-510) and
control passed back to the MOS (line 520). When the command *NOBASIC
is intercepted the accumulator is loaded with &8E (line 680) and the X
register is loaded with the rom number stored in &F4 (line 690) and a
jump is made to Osbyte (line 700) to enter the rom at its language
entry point. There is no return from Osbyte &8E.
The simple help routine (line 710-840) is used to print the rom
title in response to the *HELP command. The argument is initialised
(line 720) and, if an argumemt has been typed, the zero flag will be
clear on return from Gsinit. The zero flag is tested (line 730) and if
clear extended help has been requested. Extended help is not usually
provided by language roms and so the registers are restored (line 730
and lines 470-510) and control is passed back to the MOS (line 520).
If simple help is requested the rom title is printed (lines 740-830),
the registers are restored (line 850 and lines 460-510) and control is
passed back to the MOS (line 520).
Following the Osbyte &8E call (lines 680-700) the rom will be
entered at its language entry point (line 850) via the jump
instruction in the rom header (line 220). The language must enable
interupt requests (line 860), reset the stack (lines 870-880) and
re-vector the BREAKV at &202 and &203 (lines 890-920) to point to its
own error handling routine starting at the label ".error" (line 1180).
Error handling in language roms is different to that in service
roms. In a service rom you copy the error message, preceded and
followed by a BRK instruction, into the error buffer and then jump to
the first BRK instruction of the error message, (see Module 8). When
the MOS processes the BRK instruction it passes the error to the
current active language via the break vector. The error message is
pointed to by the error vector at &FD and &FE. The language error
handler must use the error vector to print out the error message, then
re-initialise the stack and pass control back to some well defined
part of the language, such as the input prompt. NOBASIC jumps back to
the language entry point after printing the error message. A more
complex language would probably not use this shortcut.
The error handler in NOBASIC is in lines 1180 to 1290. The MOS
processes a BRK instruction by passing control, via the break vector,
to the label ".error" (line 1180). The error vector points to the byte
following the BRK instruction. This is the error number and it is not
printed. The error routine prints every byte of the error message
(lines 1200-1260) until it reads the zero byte at the end (line 1240)
when it prints a new line to make the printed message look neat (line
1280). It then passes control back to the language initialisation
routine (line 1290 and lines 850-920) to reset the stack and issue the
input prompt.
The coding that implements the language is in lines 930 to 1040.
This must be one of the smallest languages possible. The input prompt
"*" is printed (line 940-950) and an Osword buffer in page &07 is used
to input a string of characters from the keyboard (lines 960-990). The
address of the Osword buffer is stored in the first two bytes of the
Osword parameter block (lines 1050-1100) and this address is sent to
the command line interpreter to process the input (lines 1010-1030).
After returning from the CLI (1040) control is passed back to the
input prompt routine (line 940) for more input.
The only error that can be easily generated within the language can
be made by pressing the Escape key when inputing text at the keyboard.
This error is trapped (line 1000) when Osword returns with the carry
flag set. If an escape is flaged it is acknowledged (lines 1120-1130)
and a BRK instruction is executed to signal the error (line 1140). The
BRK instruction is followed by an error number (line 1150), an error
message (line 1160), and an end of message zero byte (line 1170). The
error will be dealt with as described above.
10 REM: NOBASIC
20 MODE7
30 HIMEM=&3C00
40 DIM save 50
50 diff=&8000-HIMEM
60 comvec=&F2
70 romnumber=&F4
80 errvec=&FD
90 stack=&103
100 breakv=&202
110 buffer=&700
120 gsinit=&FFC2
130 gsread=&FFC5
140 osasci=&FFE3
150 osnewl=&FFE7
160 osword=&FFF1
170 osbyte=&FFF4
180 oscli=&FFF7
190 FOR pass = 0 TO 2 STEP 2
200 P%=HIMEM
210 [ OPT pass
220 JMP language+diff
230 JMP service+diff
240 OPT FNequb(&C2)
250 OPT FNequb((copyright+diff) MOD 256)
260 BRK
270 .title
280 OPT FNequs("NOBASIC")
290 BRK
300 .copyright
310 BRK
320 OPT FNequs("(C) Gordon Horsington 1987")
330 BRK
340 .service
350 PHA
360 TXA
370 PHA
380 TYA
390 PHA
400 TSX
410 LDA stack,X
420 CMP #4
430 BEQ unrecognised
440 CMP #9
450 BEQ help
460 .finish
470 PLA
480 TAY
490 PLA
500 TAX
510 PLA
520 RTS
530 .unrecognised
540 LDX #&FF
550 .comloop
560 INX
570 LDA title+diff,X
580 BEQ found
590 LDA (comvec),Y
600 INY
610 CMP #ASC(".")
620 BEQ found
630 AND #&DF
640 CMP title+diff,X
650 BEQ comloop
660 BNE finish
670 .found
680 LDA #&8E
690 LDX romnumber
700 JMP osbyte \ Enter this ROM
710 .help
720 JSR gsinit
730 BNE finish \ No extended help available
740 JSR osnewl
750 LDX #&FF
760 .helploop
770 INX
780 LDA title+diff,X
790 BEQ endtitle
800 JSR osasci
810 BNE helploop
820 .endtitle
830 JSR osnewl
840 JMP finish+diff
850 .language
860 CLI \ Enable interupt requests
870 LDX #&FF
880 TXS \ Reset stack
890 LDA #(error+diff) MOD 256
900 STA breakv
910 LDA #(error+diff) DIV 256
920 STA breakv+1
930 .continue
940 LDA #ASC("*")
950 JSR osasci
960 LDA #0
970 LDX #(block+diff) MOD 256
980 LDY #(block+diff) DIV 256
990 JSR osword
1000 BCS escape
1010 LDX block+diff
1020 LDY block+diff+1
1030 JSR oscli
1040 JMP continue+diff
1050 .block
1060 OPT FNequb(buffer MOD 256)
1070 OPT FNequb(buffer DIV 256)
1080 OPT FNequb(&FE)
1090 OPT FNequb(&20)
1100 OPT FNequb(&7F)
1110 .escape
1120 LDA #&7E
1130 JSR osbyte \ Acknowledge Escape
1140 BRK
1150 BRK
1160 OPT FNequs("Escape")
1170 BRK
1180 .error
1190 JSR osnewl
1200 LDY #0
1210 .errorloop
1220 INY
1230 LDA (errvec),Y
1240 BEQ newline
1250 JSR osasci
1260 BNE errorloop
1270 .newline
1280 JSR osnewl
1290 JMP language+diff
1300 .lastbyte
1310 ]
1320 NEXT
1330 INPUT'"Save filename = "filename$
1340 IF filename$="" END
1350 $save="SAVE "+filename$+" "+STR$~(HIMEM)+" "+STR$~(las
tbyte)+" FFFF8000 FFFF8000"
1360 X%=save MOD 256
1370 Y%=save DIV 256
1380 *OPT1,2
1390 CALL oscli
1400 *OPT1,0
1410 END
1420 DEFFNequb(byte)
1430 ?P%=byte
1440 P%=P%+1
1450 =pass
1460 DEFFNequw(word)
1470 ?P%=word MOD 256
1480 P%?1=word DIV 256
1490 P%=P%+2
1500 =pass
1510 DEFFNequd(double)
1520 !P%=double
1530 P%=P%+4
1540 =pass
1550 DEFFNequs(string$)
1560 $P%=string$
1570 P%=P%+LEN(string$)
1580 =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 31 37 20 2d 20 4c 61 6e 67 75 |odule 17 - Langu|
00000030 61 67 65 20 52 6f 6d 73 0d 2d 2d 2d 2d 2d 2d 2d |age Roms.-------|
00000040 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
*
00000070 2d 0d 0d 20 20 54 68 65 20 66 69 72 73 74 20 31 |-.. The first 1|
00000080 36 20 6d 6f 64 75 6c 65 73 20 6f 66 20 74 68 69 |6 modules of thi|
00000090 73 20 63 6f 75 72 73 65 20 68 61 76 65 20 64 65 |s course have de|
000000a0 61 6c 74 20 61 6c 6d 6f 73 74 20 65 78 63 6c 75 |alt almost exclu|
000000b0 73 69 76 65 6c 79 0d 77 69 74 68 20 74 68 65 20 |sively.with the |
000000c0 64 65 73 69 67 6e 20 6f 66 20 73 65 72 76 69 63 |design of servic|
000000d0 65 20 72 6f 6d 73 2e 20 54 68 65 20 72 65 73 74 |e roms. The rest|
000000e0 20 6f 66 20 74 68 65 20 63 6f 75 72 73 65 20 77 | of the course w|
000000f0 69 6c 6c 20 62 65 0d 64 65 61 6c 69 6e 67 20 77 |ill be.dealing w|
00000100 69 74 68 20 74 68 65 20 64 65 73 69 67 6e 20 6f |ith the design o|
00000110 66 20 72 6f 6d 73 20 74 68 61 74 20 75 73 65 20 |f roms that use |
00000120 62 6f 74 68 20 6c 61 6e 67 75 61 67 65 20 61 6e |both language an|
00000130 64 20 73 65 72 76 69 63 65 0d 65 6e 74 72 79 20 |d service.entry |
00000140 70 6f 69 6e 74 73 2e 0d 0d 20 20 41 20 6e 65 77 |points... A new|
00000150 20 6c 61 6e 67 75 61 67 65 20 64 6f 65 73 20 6e | language does n|
00000160 6f 74 20 6e 65 65 64 20 74 68 65 20 63 6f 6d 70 |ot need the comp|
00000170 6c 65 78 69 74 79 20 6f 66 20 61 20 6e 65 77 20 |lexity of a new |
00000180 64 69 61 6c 65 63 74 20 6f 66 0d 42 41 53 49 43 |dialect of.BASIC|
00000190 2e 20 49 74 20 73 69 6d 70 6c 79 20 6e 65 65 64 |. It simply need|
000001a0 73 20 74 6f 20 62 65 20 61 20 73 65 6c 66 20 63 |s to be a self c|
000001b0 6f 6e 74 61 69 6e 65 64 20 6d 61 63 68 69 6e 65 |ontained machine|
000001c0 20 63 6f 64 65 20 70 72 6f 67 72 61 6d 0d 77 68 | code program.wh|
000001d0 69 63 68 20 69 73 20 74 6f 74 61 6c 6c 79 20 69 |ich is totally i|
000001e0 6e 64 65 70 65 6e 64 61 6e 74 20 6f 66 20 61 6e |ndependant of an|
000001f0 79 20 6f 74 68 65 72 20 6c 61 6e 67 75 61 67 65 |y other language|
00000200 2e 20 4c 61 6e 67 75 61 67 65 20 72 6f 6d 73 20 |. Language roms |
00000210 68 61 76 65 0d 61 63 63 65 73 73 20 74 6f 20 6d |have.access to m|
00000220 65 6d 6f 72 79 20 66 72 6f 6d 20 26 30 30 20 74 |emory from &00 t|
00000230 6f 20 26 38 46 20 61 73 20 7a 65 72 6f 20 70 61 |o &8F as zero pa|
00000240 67 65 20 77 6f 72 6b 73 70 61 63 65 2c 20 66 72 |ge workspace, fr|
00000250 6f 6d 20 26 30 34 30 30 20 74 6f 0d 26 30 37 46 |om &0400 to.&07F|
00000260 46 20 61 73 20 6d 61 69 6e 20 6c 61 6e 67 75 61 |F as main langua|
00000270 67 65 20 77 6f 72 6b 73 70 61 63 65 20 61 6e 64 |ge workspace and|
00000280 20 66 72 6f 6d 20 4f 73 68 77 6d 20 74 6f 20 74 | from Oshwm to t|
00000290 68 65 20 62 6f 74 74 6f 6d 20 6f 66 0d 73 63 72 |he bottom of.scr|
000002a0 65 65 6e 20 6d 65 6d 6f 72 79 20 61 73 20 70 72 |een memory as pr|
000002b0 6f 67 72 61 6d 20 73 70 61 63 65 2e 0d 0d 20 20 |ogram space... |
000002c0 54 68 65 20 70 72 6f 67 72 61 6d 20 4e 4f 42 41 |The program NOBA|
000002d0 53 49 43 20 69 73 20 61 20 67 6f 6f 64 20 65 78 |SIC is a good ex|
000002e0 61 6d 70 6c 65 20 6f 66 20 61 6e 20 65 78 74 72 |ample of an extr|
000002f0 65 6d 65 6c 79 20 73 69 6d 70 6c 65 0d 6c 61 6e |emely simple.lan|
00000300 67 75 61 67 65 2e 20 55 6e 6c 69 6b 65 20 42 41 |guage. Unlike BA|
00000310 53 49 43 20 69 74 20 68 61 73 20 6e 6f 20 6b 65 |SIC it has no ke|
00000320 79 77 6f 72 64 73 20 61 6e 64 20 6f 6e 6c 79 20 |ywords and only |
00000330 70 72 6f 63 65 73 73 65 73 20 2a 0d 63 6f 6d 6d |processes *.comm|
00000340 61 6e 64 73 2e 20 49 74 20 75 73 65 73 20 61 6e |ands. It uses an|
00000350 20 4f 73 77 6f 72 64 20 63 61 6c 6c 20 74 6f 20 | Osword call to |
00000360 72 65 61 64 20 69 6e 70 75 74 20 66 72 6f 6d 20 |read input from |
00000370 74 68 65 20 6b 65 79 62 6f 61 72 64 20 69 6e 74 |the keyboard int|
00000380 6f 0d 61 20 62 75 66 66 65 72 20 69 6e 20 70 61 |o.a buffer in pa|
00000390 67 65 20 26 30 37 20 61 6e 64 20 70 61 73 73 65 |ge &07 and passe|
000003a0 73 20 74 68 61 74 20 69 6e 70 75 74 20 74 6f 20 |s that input to |
000003b0 74 68 65 20 63 6f 6d 6d 61 6e 64 20 6c 69 6e 65 |the command line|
000003c0 0d 69 6e 74 65 72 70 72 65 74 65 72 20 28 43 4c |.interpreter (CL|
000003d0 49 29 20 66 6f 72 20 66 75 72 74 68 65 72 20 70 |I) for further p|
000003e0 72 6f 63 65 73 73 69 6e 67 2e 20 54 68 65 20 72 |rocessing. The r|
000003f0 65 74 75 72 6e 20 66 72 6f 6d 20 74 68 65 20 43 |eturn from the C|
00000400 4c 49 20 67 6f 65 73 0d 62 61 63 6b 20 66 6f 72 |LI goes.back for|
00000410 20 6d 6f 72 65 20 69 6e 70 75 74 20 77 68 69 63 | more input whic|
00000420 68 20 69 73 20 70 61 73 73 65 64 20 74 6f 20 74 |h is passed to t|
00000430 68 65 20 43 4c 49 2c 20 61 6e 64 20 73 6f 20 6f |he CLI, and so o|
00000440 6e 20 61 6e 64 20 6f 6e 20 75 6e 74 69 6c 0d 61 |n and on until.a|
00000450 6e 6f 74 68 65 72 20 6c 61 6e 67 75 61 67 65 20 |nother language |
00000460 69 73 20 73 65 6c 65 63 74 65 64 20 74 6f 20 72 |is selected to r|
00000470 65 70 6c 61 63 65 20 69 74 2e 20 41 6c 74 68 6f |eplace it. Altho|
00000480 75 67 68 20 4e 4f 42 41 53 49 43 20 68 61 73 20 |ugh NOBASIC has |
00000490 6e 6f 0d 6b 65 79 77 6f 72 64 73 20 69 74 20 6d |no.keywords it m|
000004a0 65 65 74 73 20 61 6c 6c 20 74 68 65 20 72 65 71 |eets all the req|
000004b0 75 69 72 65 6d 65 6e 74 73 20 66 6f 72 20 61 20 |uirements for a |
000004c0 6c 61 6e 67 75 61 67 65 2e 20 49 74 20 69 73 20 |language. It is |
000004d0 73 65 6c 66 0d 63 6f 6e 74 61 69 6e 65 64 20 61 |self.contained a|
000004e0 6e 64 20 63 6f 6d 70 6c 65 74 65 6c 79 20 69 6e |nd completely in|
000004f0 64 65 70 65 6e 64 61 6e 74 20 6f 66 20 61 6e 79 |dependant of any|
00000500 20 6f 74 68 65 72 20 6c 61 6e 67 75 61 67 65 2e | other language.|
00000510 0d 0d 20 20 54 6f 20 75 73 65 20 74 68 65 20 6c |.. To use the l|
00000520 61 6e 67 75 61 67 65 20 6c 6f 61 64 20 74 68 65 |anguage load the|
00000530 20 6f 62 6a 65 63 74 20 63 6f 64 65 20 67 65 6e | object code gen|
00000540 65 72 61 74 65 64 20 62 79 20 4e 4f 42 41 53 49 |erated by NOBASI|
00000550 43 20 69 6e 74 6f 0d 53 57 52 20 61 6e 64 20 70 |C into.SWR and p|
00000560 72 65 73 73 20 74 68 65 20 42 72 65 61 6b 20 6b |ress the Break k|
00000570 65 79 2e 20 54 79 70 65 20 2a 4e 4f 42 41 53 49 |ey. Type *NOBASI|
00000580 43 20 61 6e 64 20 70 72 65 73 73 20 52 65 74 75 |C and press Retu|
00000590 72 6e 2e 20 54 68 65 0d 6c 61 6e 67 75 61 67 65 |rn. The.language|
000005a0 20 74 69 74 6c 65 20 61 6e 64 20 61 20 22 2a 22 | title and a "*"|
000005b0 20 70 72 6f 6d 70 74 20 77 69 6c 6c 20 62 65 20 | prompt will be |
000005c0 70 72 69 6e 74 65 64 2e 20 54 68 65 20 6c 61 6e |printed. The lan|
000005d0 67 75 61 67 65 20 77 69 6c 6c 0d 6f 6e 6c 79 20 |guage will.only |
000005e0 61 6c 6c 6f 77 20 79 6f 75 20 74 6f 20 75 73 65 |allow you to use|
000005f0 20 6f 70 65 72 61 74 69 6e 67 20 73 79 73 74 65 | operating syste|
00000600 6d 2c 20 66 69 6c 69 6e 67 20 73 79 73 74 65 6d |m, filing system|
00000610 20 61 6e 64 20 73 65 72 76 69 63 65 20 72 6f 6d | and service rom|
00000620 0d 63 6f 6d 6d 61 6e 64 73 2e 20 54 68 65 72 65 |.commands. There|
00000630 20 69 73 20 6e 6f 20 6e 65 65 64 20 74 6f 20 74 | is no need to t|
00000640 79 70 65 20 74 68 65 20 2a 20 70 72 65 66 69 78 |ype the * prefix|
00000650 20 66 6f 72 20 74 68 65 73 65 20 63 6f 6d 6d 61 | for these comma|
00000660 6e 64 73 2e 0d 49 66 2c 20 66 6f 72 20 65 78 61 |nds..If, for exa|
00000670 6d 70 6c 65 2c 20 79 6f 75 20 77 61 6e 74 20 74 |mple, you want t|
00000680 6f 20 72 65 74 75 72 6e 20 74 6f 20 42 41 53 49 |o return to BASI|
00000690 43 20 6a 75 73 74 20 74 79 70 65 20 42 41 53 49 |C just type BASI|
000006a0 43 2e 0d 0d 20 20 57 68 65 6e 20 73 74 61 72 74 |C... When start|
000006b0 69 6e 67 20 75 70 20 61 20 6c 61 6e 67 75 61 67 |ing up a languag|
000006c0 65 20 74 68 65 20 4d 4f 53 20 64 6f 65 73 20 74 |e the MOS does t|
000006d0 68 65 20 66 6f 6c 6c 6f 77 69 6e 67 3a 0d 0d 31 |he following:..1|
000006e0 2e 20 52 65 63 6f 72 64 73 20 74 68 65 20 6e 75 |. Records the nu|
000006f0 6d 62 65 72 20 6f 66 20 74 68 65 20 72 6f 6d 20 |mber of the rom |
00000700 73 6f 20 74 68 61 74 20 69 74 20 63 61 6e 20 72 |so that it can r|
00000710 65 73 65 6c 65 63 74 20 74 68 65 20 6c 61 6e 67 |eselect the lang|
00000720 75 61 67 65 0d 77 68 65 6e 20 61 20 42 52 4b 20 |uage.when a BRK |
00000730 69 6e 73 74 72 75 63 74 69 6f 6e 20 69 73 20 65 |instruction is e|
00000740 78 65 63 75 74 65 64 20 61 6e 64 20 77 68 65 6e |xecuted and when|
00000750 20 74 68 65 20 42 72 65 61 6b 20 6b 65 79 20 69 | the Break key i|
00000760 73 20 70 72 65 73 73 65 64 0d 28 61 20 22 73 6f |s pressed.(a "so|
00000770 66 74 22 20 62 72 65 61 6b 29 2e 0d 0d 32 2e 20 |ft" break)...2. |
00000780 44 69 73 70 6c 61 79 73 20 74 68 65 20 72 6f 6d |Displays the rom|
00000790 20 74 69 74 6c 65 20 73 74 72 69 6e 67 20 74 6f | title string to|
000007a0 20 69 6e 64 69 63 61 74 65 20 74 68 65 20 70 61 | indicate the pa|
000007b0 72 74 69 63 75 6c 61 72 20 6c 61 6e 67 75 61 67 |rticular languag|
000007c0 65 0d 69 73 20 69 6e 20 75 73 65 2e 0d 0d 33 2e |e.is in use...3.|
000007d0 20 50 6f 69 6e 74 73 20 74 68 65 20 65 72 72 6f | Points the erro|
000007e0 72 20 6d 65 73 73 61 67 65 20 76 65 63 74 6f 72 |r message vector|
000007f0 20 74 6f 20 74 68 65 20 63 6f 70 79 72 69 67 68 | to the copyrigh|
00000800 74 20 6d 65 73 73 61 67 65 2c 20 6f 72 20 74 68 |t message, or th|
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00002950 20 20 20 20 20 20 20 4f 50 54 20 46 4e 65 71 75 | OPT FNequ|
00002960 62 28 26 43 32 29 0d 20 20 32 35 30 20 20 20 20 |b(&C2). 250 |
00002970 20 20 20 20 20 4f 50 54 20 46 4e 65 71 75 62 28 | OPT FNequb(|
00002980 28 63 6f 70 79 72 69 67 68 74 2b 64 69 66 66 29 |(copyright+diff)|
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000029a0 20 20 20 20 20 20 20 20 42 52 4b 0d 20 20 32 37 | BRK. 27|
000029b0 30 20 2e 74 69 74 6c 65 0d 20 20 32 38 30 20 20 |0 .title. 280 |
000029c0 20 20 20 20 20 20 20 4f 50 54 20 46 4e 65 71 75 | OPT FNequ|
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000029f0 20 33 30 30 20 2e 63 6f 70 79 72 69 67 68 74 0d | 300 .copyright.|
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00002aa0 20 20 33 38 30 20 20 20 20 20 20 20 20 20 54 59 | 380 TY|
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00002ac0 50 48 41 0d 20 20 34 30 30 20 20 20 20 20 20 20 |PHA. 400 |
00002ad0 20 20 54 53 58 0d 20 20 34 31 30 20 20 20 20 20 | TSX. 410 |
00002ae0 20 20 20 20 4c 44 41 20 73 74 61 63 6b 2c 58 0d | LDA stack,X.|
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00002b00 50 20 23 34 0d 20 20 34 33 30 20 20 20 20 20 20 |P #4. 430 |
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00002b30 20 20 43 4d 50 20 23 39 0d 20 20 34 35 30 20 20 | CMP #9. 450 |
00002b40 20 20 20 20 20 20 20 42 45 51 20 68 65 6c 70 0d | BEQ help.|
00002b50 20 20 34 36 30 20 2e 66 69 6e 69 73 68 0d 20 20 | 460 .finish. |
00002b60 34 37 30 20 20 20 20 20 20 20 20 20 50 4c 41 0d |470 PLA.|
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00002ba0 20 20 54 41 58 0d 20 20 35 31 30 20 20 20 20 20 | TAX. 510 |
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00002bc0 20 20 20 20 20 20 52 54 53 0d 20 20 35 33 30 20 | RTS. 530 |
00002bd0 2e 75 6e 72 65 63 6f 67 6e 69 73 65 64 0d 20 20 |.unrecognised. |
00002be0 35 34 30 20 20 20 20 20 20 20 20 20 4c 44 58 20 |540 LDX |
00002bf0 23 26 46 46 0d 20 20 35 35 30 20 2e 63 6f 6d 6c |#&FF. 550 .coml|
00002c00 6f 6f 70 0d 20 20 35 36 30 20 20 20 20 20 20 20 |oop. 560 |
00002c10 20 20 49 4e 58 0d 20 20 35 37 30 20 20 20 20 20 | INX. 570 |
00002c20 20 20 20 20 4c 44 41 20 74 69 74 6c 65 2b 64 69 | LDA title+di|
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00002c40 20 20 20 42 45 51 20 66 6f 75 6e 64 0d 20 20 35 | BEQ found. 5|
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00002c60 63 6f 6d 76 65 63 29 2c 59 0d 20 20 36 30 30 20 |comvec),Y. 600 |
00002c70 20 20 20 20 20 20 20 20 49 4e 59 0d 20 20 36 31 | INY. 61|
00002c80 30 20 20 20 20 20 20 20 20 20 43 4d 50 20 23 41 |0 CMP #A|
00002c90 53 43 28 22 2e 22 29 0d 20 20 36 32 30 20 20 20 |SC("."). 620 |
00002ca0 20 20 20 20 20 20 42 45 51 20 66 6f 75 6e 64 0d | BEQ found.|
00002cb0 20 20 36 33 30 20 20 20 20 20 20 20 20 20 41 4e | 630 AN|
00002cc0 44 20 23 26 44 46 0d 20 20 36 34 30 20 20 20 20 |D #&DF. 640 |
00002cd0 20 20 20 20 20 43 4d 50 20 74 69 74 6c 65 2b 64 | CMP title+d|
00002ce0 69 66 66 2c 58 0d 20 20 36 35 30 20 20 20 20 20 |iff,X. 650 |
00002cf0 20 20 20 20 42 45 51 20 63 6f 6d 6c 6f 6f 70 0d | BEQ comloop.|
00002d00 20 20 36 36 30 20 20 20 20 20 20 20 20 20 42 4e | 660 BN|
00002d10 45 20 66 69 6e 69 73 68 0d 20 20 36 37 30 20 2e |E finish. 670 .|
00002d20 66 6f 75 6e 64 0d 20 20 36 38 30 20 20 20 20 20 |found. 680 |
00002d30 20 20 20 20 4c 44 41 20 23 26 38 45 0d 20 20 36 | LDA #&8E. 6|
00002d40 39 30 20 20 20 20 20 20 20 20 20 4c 44 58 20 72 |90 LDX r|
00002d50 6f 6d 6e 75 6d 62 65 72 0d 20 20 37 30 30 20 20 |omnumber. 700 |
00002d60 20 20 20 20 20 20 20 4a 4d 50 20 6f 73 62 79 74 | JMP osbyt|
00002d70 65 20 20 20 20 5c 20 45 6e 74 65 72 20 74 68 69 |e \ Enter thi|
00002d80 73 20 52 4f 4d 0d 20 20 37 31 30 20 2e 68 65 6c |s ROM. 710 .hel|
00002d90 70 0d 20 20 37 32 30 20 20 20 20 20 20 20 20 20 |p. 720 |
00002da0 4a 53 52 20 67 73 69 6e 69 74 0d 20 20 37 33 30 |JSR gsinit. 730|
00002db0 20 20 20 20 20 20 20 20 20 42 4e 45 20 66 69 6e | BNE fin|
00002dc0 69 73 68 20 20 20 20 5c 20 4e 6f 20 65 78 74 65 |ish \ No exte|
00002dd0 6e 64 65 64 20 68 65 6c 70 20 61 76 61 69 6c 61 |nded help availa|
00002de0 62 6c 65 0d 20 20 37 34 30 20 20 20 20 20 20 20 |ble. 740 |
00002df0 20 20 4a 53 52 20 6f 73 6e 65 77 6c 0d 20 20 37 | JSR osnewl. 7|
00002e00 35 30 20 20 20 20 20 20 20 20 20 4c 44 58 20 23 |50 LDX #|
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00002e20 6f 6f 70 0d 20 20 37 37 30 20 20 20 20 20 20 20 |oop. 770 |
00002e30 20 20 49 4e 58 0d 20 20 37 38 30 20 20 20 20 20 | INX. 780 |
00002e40 20 20 20 20 4c 44 41 20 74 69 74 6c 65 2b 64 69 | LDA title+di|
00002e50 66 66 2c 58 0d 20 20 37 39 30 20 20 20 20 20 20 |ff,X. 790 |
00002e60 20 20 20 42 45 51 20 65 6e 64 74 69 74 6c 65 0d | BEQ endtitle.|
00002e70 20 20 38 30 30 20 20 20 20 20 20 20 20 20 4a 53 | 800 JS|
00002e80 52 20 6f 73 61 73 63 69 0d 20 20 38 31 30 20 20 |R osasci. 810 |
00002e90 20 20 20 20 20 20 20 42 4e 45 20 68 65 6c 70 6c | BNE helpl|
00002ea0 6f 6f 70 0d 20 20 38 32 30 20 2e 65 6e 64 74 69 |oop. 820 .endti|
00002eb0 74 6c 65 0d 20 20 38 33 30 20 20 20 20 20 20 20 |tle. 830 |
00002ec0 20 20 4a 53 52 20 6f 73 6e 65 77 6c 0d 20 20 38 | JSR osnewl. 8|
00002ed0 34 30 20 20 20 20 20 20 20 20 20 4a 4d 50 20 66 |40 JMP f|
00002ee0 69 6e 69 73 68 2b 64 69 66 66 0d 20 20 38 35 30 |inish+diff. 850|
00002ef0 20 2e 6c 61 6e 67 75 61 67 65 0d 20 20 38 36 30 | .language. 860|
00002f00 20 20 20 20 20 20 20 20 20 43 4c 49 20 20 20 20 | CLI |
00002f10 20 20 20 20 20 20 20 5c 20 45 6e 61 62 6c 65 20 | \ Enable |
00002f20 69 6e 74 65 72 75 70 74 20 72 65 71 75 65 73 74 |interupt request|
00002f30 73 0d 20 20 38 37 30 20 20 20 20 20 20 20 20 20 |s. 870 |
00002f40 4c 44 58 20 23 26 46 46 0d 20 20 38 38 30 20 20 |LDX #&FF. 880 |
00002f50 20 20 20 20 20 20 20 54 58 53 20 20 20 20 20 20 | TXS |
00002f60 20 20 20 20 20 5c 20 52 65 73 65 74 20 73 74 61 | \ Reset sta|
00002f70 63 6b 0d 20 20 38 39 30 20 20 20 20 20 20 20 20 |ck. 890 |
00002f80 20 4c 44 41 20 23 28 65 72 72 6f 72 2b 64 69 66 | LDA #(error+dif|
00002f90 66 29 20 4d 4f 44 20 32 35 36 0d 20 20 39 30 30 |f) MOD 256. 900|
00002fa0 20 20 20 20 20 20 20 20 20 53 54 41 20 62 72 65 | STA bre|
00002fb0 61 6b 76 0d 20 20 39 31 30 20 20 20 20 20 20 20 |akv. 910 |
00002fc0 20 20 4c 44 41 20 23 28 65 72 72 6f 72 2b 64 69 | LDA #(error+di|
00002fd0 66 66 29 20 44 49 56 20 32 35 36 0d 20 20 39 32 |ff) DIV 256. 92|
00002fe0 30 20 20 20 20 20 20 20 20 20 53 54 41 20 62 72 |0 STA br|
00002ff0 65 61 6b 76 2b 31 0d 20 20 39 33 30 20 2e 63 6f |eakv+1. 930 .co|
00003000 6e 74 69 6e 75 65 0d 20 20 39 34 30 20 20 20 20 |ntinue. 940 |
00003010 20 20 20 20 20 4c 44 41 20 23 41 53 43 28 22 2a | LDA #ASC("*|
00003020 22 29 0d 20 20 39 35 30 20 20 20 20 20 20 20 20 |"). 950 |
00003030 20 4a 53 52 20 6f 73 61 73 63 69 0d 20 20 39 36 | JSR osasci. 96|
00003040 30 20 20 20 20 20 20 20 20 20 4c 44 41 20 23 30 |0 LDA #0|
00003050 0d 20 20 39 37 30 20 20 20 20 20 20 20 20 20 4c |. 970 L|
00003060 44 58 20 23 28 62 6c 6f 63 6b 2b 64 69 66 66 29 |DX #(block+diff)|
00003070 20 4d 4f 44 20 32 35 36 0d 20 20 39 38 30 20 20 | MOD 256. 980 |
00003080 20 20 20 20 20 20 20 4c 44 59 20 23 28 62 6c 6f | LDY #(blo|
00003090 63 6b 2b 64 69 66 66 29 20 44 49 56 20 32 35 36 |ck+diff) DIV 256|
000030a0 0d 20 20 39 39 30 20 20 20 20 20 20 20 20 20 4a |. 990 J|
000030b0 53 52 20 6f 73 77 6f 72 64 0d 20 31 30 30 30 20 |SR osword. 1000 |
000030c0 20 20 20 20 20 20 20 20 42 43 53 20 65 73 63 61 | BCS esca|
000030d0 70 65 0d 20 31 30 31 30 20 20 20 20 20 20 20 20 |pe. 1010 |
000030e0 20 4c 44 58 20 62 6c 6f 63 6b 2b 64 69 66 66 0d | LDX block+diff.|
000030f0 20 31 30 32 30 20 20 20 20 20 20 20 20 20 4c 44 | 1020 LD|
00003100 59 20 62 6c 6f 63 6b 2b 64 69 66 66 2b 31 0d 20 |Y block+diff+1. |
00003110 31 30 33 30 20 20 20 20 20 20 20 20 20 4a 53 52 |1030 JSR|
00003120 20 6f 73 63 6c 69 0d 20 31 30 34 30 20 20 20 20 | oscli. 1040 |
00003130 20 20 20 20 20 4a 4d 50 20 63 6f 6e 74 69 6e 75 | JMP continu|
00003140 65 2b 64 69 66 66 0d 20 31 30 35 30 20 2e 62 6c |e+diff. 1050 .bl|
00003150 6f 63 6b 0d 20 31 30 36 30 20 20 20 20 20 20 20 |ock. 1060 |
00003160 20 20 4f 50 54 20 46 4e 65 71 75 62 28 62 75 66 | OPT FNequb(buf|
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00003180 37 30 20 20 20 20 20 20 20 20 20 4f 50 54 20 46 |70 OPT F|
00003190 4e 65 71 75 62 28 62 75 66 66 65 72 20 44 49 56 |Nequb(buffer DIV|
000031a0 20 32 35 36 29 0d 20 31 30 38 30 20 20 20 20 20 | 256). 1080 |
000031b0 20 20 20 20 4f 50 54 20 46 4e 65 71 75 62 28 26 | OPT FNequb(&|
000031c0 46 45 29 0d 20 31 30 39 30 20 20 20 20 20 20 20 |FE). 1090 |
000031d0 20 20 4f 50 54 20 46 4e 65 71 75 62 28 26 32 30 | OPT FNequb(&20|
000031e0 29 0d 20 31 31 30 30 20 20 20 20 20 20 20 20 20 |). 1100 |
000031f0 4f 50 54 20 46 4e 65 71 75 62 28 26 37 46 29 0d |OPT FNequb(&7F).|
00003200 20 31 31 31 30 20 2e 65 73 63 61 70 65 0d 20 31 | 1110 .escape. 1|
00003210 31 32 30 20 20 20 20 20 20 20 20 20 4c 44 41 20 |120 LDA |
00003220 23 26 37 45 0d 20 31 31 33 30 20 20 20 20 20 20 |#&7E. 1130 |
00003230 20 20 20 4a 53 52 20 6f 73 62 79 74 65 20 20 20 | JSR osbyte |
00003240 20 5c 20 41 63 6b 6e 6f 77 6c 65 64 67 65 20 45 | \ Acknowledge E|
00003250 73 63 61 70 65 0d 20 31 31 34 30 20 20 20 20 20 |scape. 1140 |
00003260 20 20 20 20 42 52 4b 0d 20 31 31 35 30 20 20 20 | BRK. 1150 |
00003270 20 20 20 20 20 20 42 52 4b 0d 20 31 31 36 30 20 | BRK. 1160 |
00003280 20 20 20 20 20 20 20 20 4f 50 54 20 46 4e 65 71 | OPT FNeq|
00003290 75 73 28 22 45 73 63 61 70 65 22 29 0d 20 31 31 |us("Escape"). 11|
000032a0 37 30 20 20 20 20 20 20 20 20 20 42 52 4b 0d 20 |70 BRK. |
000032b0 31 31 38 30 20 2e 65 72 72 6f 72 0d 20 31 31 39 |1180 .error. 119|
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000032e0 20 20 20 4c 44 59 20 23 30 0d 20 31 32 31 30 20 | LDY #0. 1210 |
000032f0 2e 65 72 72 6f 72 6c 6f 6f 70 0d 20 31 32 32 30 |.errorloop. 1220|
00003300 20 20 20 20 20 20 20 20 20 49 4e 59 0d 20 31 32 | INY. 12|
00003310 33 30 20 20 20 20 20 20 20 20 20 4c 44 41 20 28 |30 LDA (|
00003320 65 72 72 76 65 63 29 2c 59 0d 20 31 32 34 30 20 |errvec),Y. 1240 |
00003330 20 20 20 20 20 20 20 20 42 45 51 20 6e 65 77 6c | BEQ newl|
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00003350 20 20 4a 53 52 20 6f 73 61 73 63 69 0d 20 31 32 | JSR osasci. 12|
00003360 36 30 20 20 20 20 20 20 20 20 20 42 4e 45 20 65 |60 BNE e|
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00003380 6e 65 77 6c 69 6e 65 0d 20 31 32 38 30 20 20 20 |newline. 1280 |
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000033a0 0d 20 31 32 39 30 20 20 20 20 20 20 20 20 20 4a |. 1290 J|
000033b0 4d 50 20 6c 61 6e 67 75 61 67 65 2b 64 69 66 66 |MP language+diff|
000033c0 0d 20 31 33 30 30 20 2e 6c 61 73 74 62 79 74 65 |. 1300 .lastbyte|
000033d0 0d 20 31 33 31 30 20 5d 0d 20 31 33 32 30 20 4e |. 1310 ]. 1320 N|
000033e0 45 58 54 0d 20 31 33 33 30 20 49 4e 50 55 54 27 |EXT. 1330 INPUT'|
000033f0 22 53 61 76 65 20 66 69 6c 65 6e 61 6d 65 20 3d |"Save filename =|
00003400 20 22 66 69 6c 65 6e 61 6d 65 24 0d 20 31 33 34 | "filename$. 134|
00003410 30 20 49 46 20 66 69 6c 65 6e 61 6d 65 24 3d 22 |0 IF filename$="|
00003420 22 20 45 4e 44 0d 20 31 33 35 30 20 24 73 61 76 |" END. 1350 $sav|
00003430 65 3d 22 53 41 56 45 20 22 2b 66 69 6c 65 6e 61 |e="SAVE "+filena|
00003440 6d 65 24 2b 22 20 22 2b 53 54 52 24 7e 28 48 49 |me$+" "+STR$~(HI|
00003450 4d 45 4d 29 2b 22 20 22 2b 53 54 52 24 7e 28 6c |MEM)+" "+STR$~(l|
00003460 61 73 0d 20 20 20 20 20 20 74 62 79 74 65 29 2b |as. tbyte)+|
00003470 22 20 46 46 46 46 38 30 30 30 20 46 46 46 46 38 |" FFFF8000 FFFF8|
00003480 30 30 30 22 0d 20 31 33 36 30 20 58 25 3d 73 61 |000". 1360 X%=sa|
00003490 76 65 20 4d 4f 44 20 32 35 36 0d 20 31 33 37 30 |ve MOD 256. 1370|
000034a0 20 59 25 3d 73 61 76 65 20 44 49 56 20 32 35 36 | Y%=save DIV 256|
000034b0 0d 20 31 33 38 30 20 2a 4f 50 54 31 2c 32 0d 20 |. 1380 *OPT1,2. |
000034c0 31 33 39 30 20 43 41 4c 4c 20 6f 73 63 6c 69 0d |1390 CALL oscli.|
000034d0 20 31 34 30 30 20 2a 4f 50 54 31 2c 30 0d 20 31 | 1400 *OPT1,0. 1|
000034e0 34 31 30 20 45 4e 44 0d 20 31 34 32 30 20 44 45 |410 END. 1420 DE|
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00003500 34 33 30 20 3f 50 25 3d 62 79 74 65 0d 20 31 34 |430 ?P%=byte. 14|
00003510 34 30 20 50 25 3d 50 25 2b 31 0d 20 31 34 35 30 |40 P%=P%+1. 1450|
00003520 20 3d 70 61 73 73 0d 20 31 34 36 30 20 44 45 46 | =pass. 1460 DEF|
00003530 46 4e 65 71 75 77 28 77 6f 72 64 29 0d 20 31 34 |FNequw(word). 14|
00003540 37 30 20 3f 50 25 3d 77 6f 72 64 20 4d 4f 44 20 |70 ?P%=word MOD |
00003550 32 35 36 0d 20 31 34 38 30 20 50 25 3f 31 3d 77 |256. 1480 P%?1=w|
00003560 6f 72 64 20 44 49 56 20 32 35 36 0d 20 31 34 39 |ord DIV 256. 149|
00003570 30 20 50 25 3d 50 25 2b 32 0d 20 31 35 30 30 20 |0 P%=P%+2. 1500 |
00003580 3d 70 61 73 73 0d 20 31 35 31 30 20 44 45 46 46 |=pass. 1510 DEFF|
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000035c0 34 30 20 3d 70 61 73 73 0d 20 31 35 35 30 20 44 |40 =pass. 1550 D|
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000035f0 6e 67 24 0d 20 31 35 37 30 20 50 25 3d 50 25 2b |ng$. 1570 P%=P%+|
00003600 4c 45 4e 28 73 74 72 69 6e 67 24 29 0d 20 31 35 |LEN(string$). 15|
00003610 38 30 20 3d 70 61 73 73 0d |80 =pass.|
00003619 
20-02-88/T\SWR17.m0
20-02-88/T\SWR17.m1
20-02-88/T\SWR17.m2
20-02-88/T\SWR17.m4
20-02-88/T\SWR17.m5
.