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02-09-88/T\SWR09
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 » telesoftware9.adl |
Filename: | 02-09-88/T\SWR09 |
Read OK: | ✔ |
File size: | 3B9C bytes |
Load address: | 0000 |
Exec address: | FFFFFFFF |
Duplicates
There is 1 duplicate copy of this file in the archive:
- CEEFAX disks » telesoftware4.adl » 25-12-87/T\SWR09
- CEEFAX disks » telesoftware9.adl » 02-09-88/T\SWR09
File contents
Mastering Sideways ROM & RAM - Module 09 - Numerical arguments -------------------------------------------------------------- In modules 6 and 7 you were shown how to use the MOS to read numerical arguments by defining new Osbyte and Osword routines. In this module I will show you one way of reading numerical arguments and converting them into binary. There is no one correct way of reading numerical arguments and, as with most programming problems, there are as many solutions as there are people to write them. The method I will demonstrate is quite useful for sideways ram programs because it uses the minimum amount of user memory and restores that memory after use. The method demonstrated in this module will read a hexadecimal argument in the range from &00 to &FFFF and convert the argument into a two byte binary number. The routine includes range and error checking to exclude invalid characters. The binary representation of the argument is stored in two bytes of zero page memory ready to be used by the rest of the routine. These two bytes can be restored before returning from the rom. When you design your SWR programs you should anticipate how they will be used. If the instructions for using your program tell the user to enter, for example, the hexadecimal argument one-two-three, your program should recognise &123 &0123 123 and 0123 as all the same, correct, argument. Your program should not insist on using leading zeros or an ampersand (&) prefix if a hexadecimal number is expected but it should accept them without generating an error. It is not a good idea to get your SWR program running with a * command, then prompt for a number and use Osrdch to read it byte after byte. That style of programming works but it looks very unprofessional and writing a program which allows the user to edit the number with the Delete key is quite complicated. The argument(s) should follow the command so that if, for example, you have written a program which prints the contents of a memory location and you want to use it to print the contents of location &900 your SWR interpreter should accept any of the commands in figure 9.1 to call the routine and print the answer. >*PEEK &900 <Return> >*PEEK &0900 <Return> >*peek "900" <Return> >*pe. 0900 <Return> Figure 9.1 Valid commands and arguments ---------------------------------------- Up to four ASCII characters can be used to represent a two byte hexadecimal number. The nybble represented by the first ASCII character depends on how many characters are used to represent the number. For example, the A in &AB represents the most significant nybble of the least significant byte but the A in &ABC represents the least significant nybble of the most significant byte. If you read the ASCII characters from right to left, instead of the more natural left to right, the first byte you read will always be the least significant nybble of the least significant byte. If you read the characters from left to right you either have to know in advance how many characters are used so that, if necessary, you can pad out the number with leading zeros or you have to type the leading zeros to establish the place value of each character in the argument. To convert the ASCII representation of a hexadecimal argument into binary you should start with the least significant nybble of the least significant byte unless you use an elaborate conversion algorithm or leading zeros. This presents a problem because the Gsread routine used to read the ASCII characters from the argument reads from left to right. To get round this problem you can read each nybble of the argument, convert it into binary and push it on the stack until you read the termination character. Then pull each nybble off the stack and they will be in reverse order, as if they had been read from right to left. If you keep a count of the number of nybbles read from the argument it is a simple matter to pull the nybbles off the stack and convert each nybble, or pair of nybbles, into a byte. This technique is illustrated in figure 9.2. .found CLC \ terminate with space, return or " JSR &FFC2 \ initialise argument with Gsinit LDX #0 \ initial result = &0000 STX &70 \ least sig. byte of result STX &71 \ most sig. byte of result DEX \ X will count number of nybbles - 1 .argloop JSR &FFC5 \ read character from argument with Gsread BCS endarg \ branch if termination character CMP #ASC("&") \ is it "&"? BEQ argloop \ ignore "&" JSR convert \ convert nybble into binary PHA \ push nybble on stack INX \ count nybble in X register BPL argloop \ branch for next character .endarg CPX #4 \ more than 4 characters? BCS error \ branch if too many PLA \ pull LS nybble of LS byte STA &70 \ store as LS byte DEX \ is that the only nybble? BMI finish \ branch if it is PLA \ pull MS nybble of LS byte ASL A \ shift ASL A \ left ASL A \ four ASL A \ bits ORA &70 \ OR with &70 STA &70 \ and store LS byte DEX \ was that the last nybble? BMI finish \ branch if it was PLA \ pull LS nybble of MS byte STA &71 \ store as MS byte DEX \ was that the last nybble? BMI finish \ branch if it was PLA \ pull MS nybble of MS byte ASL A \ shift ASL A \ left ASL A \ four ASL A \ bits ORA &71 \ OR with &71 STA &71 \ and store MS byte .finish Figure 9.2 Converting from ASCII to binary ----------------------------------------- After recognising the * command the interpreter will pass control to the label ".found". The carry flag should be cleared before initialising the argument so that either a second quotation mark, a carriage return or a space will be read as the termination character of the argument. In figure 9.2 the X register is loaded with zero and then the content of X is stored in the two consecutive memory locations to be used for the result. The X register will be used to count the number of ASCII characters read from the argument minus one. X is decremented to start with X = &FF when no characters have been read. The argument is read one character at a time, ignoring any leading ampersand. Each character is converted from an ASCII character into a binary nybble and pushed on the stack. The X register is incremented with every binary nybble pushed on the stack. The routine will keep reading until the termination character is found. After reading the termination character the number stored in the X register should be between 0 and 3 inclusive. If it is outside that range either too many characters have been included in the argument or the argument has been omitted. In either case a branch to an error routine will be made. When all the characters have been read from the argument the routine starts pulling the binary nybbles off the stack. The X register is decremented and tested after each nybble has been processed to see if that nybble was the first one read from the argument. There must be at least one nybble to pull off the stack and not more than four. The first nybble pulled off the stack can be stored in the memory location reserved for the least significant byte. If a second nybble is available it has all its bits shifted left four times and ORed with the first nybble to form the least significant byte. A third nybble can be stored in the memory location reserved for the most significant byte and a forth nybble should have all its bits shifted left four times and ORed with the third nybble to form the most significant byte. The result is then available from the two consecutive zero page memory locations. No other part of user memory or SWR has been used by the conversion. The error routine and the ASCII character to binary nybble conversion subroutine are only refered to by name in figure 9.2 but suitable actual routines can be found in the program PEEK. The program PEEK uses the conversion routine outlined in figure 9.2 to implement the new command *PEEK <hex.number>. To use the program load the object code it generates into SWR and press the Break key. You can use the new command to print the hexadecimal value of the number stored in any byte of the I/O processor's memory. For example, *PEEK &900, *PEEK 0900 and *PEEK "900" are all equivalent and will all print the number stored in &900 in the I/O processor's memory. The program uses a one-command interpreter (lines 300-570) similar to the ones used in the earlier modules of the course. It uses the routine in figure 9.2 to read the argument and store the binary conversion in two zero page bytes (lines 580-1050). The read and convert routine has been modified slightly to store the two zero page bytes by pushing them on the stack before making the conversion (lines 610-640). The two bytes can then be restored before returning to the MOS (lines 1100-1130). The two zero page bytes are used with post-indexed indirect addressing to load the accumulator with the byte specified by the argument (lines 1060-1070). The accumulator content is printed using the two subroutines in lines 1190-1340. After printing the result the zero page locations are restored (lines 1100-1130). The registers pushed on the stack by the interpreter are pulled off to balance the stack (lines 1140-1160). The accumulator is reset to zero (line 1170) to inform the other roms that the request has been recognised, and control is returned to the MOS (line 1180). The ASCII to binary conversion subroutine is in lines 1350 to 1480. As well as converting the ASCII character into a binary nybble the subroutine also checks for valid characters. If an invalid character is found a branch is made to an error routine (lines 1490-1660) similar to the one introduced in Module 8. Because errors can be detected at any stage of the conversion, restoring the zero page bytes when an error is found would add extra complications to the error routine. All the information you need to restore the zero page bytes from the error routine is available in the X register. If you need the exercise you could modify the error routine to restore the zero page bytes before printing the error message. If you do there is no need to balance the stack as well because it will be reset by BASIC when control passes to the BRK instruction at &100. 10 REM: PEEK 20 MODE7 30 HIMEM=&3C00 40 DIM save 50 50 diff=&8000-HIMEM 60 address=&70 70 errstack=&100 80 comvec=&F2 90 gsinit=&FFC2 100 gsread=&FFC5 110 osasci=&FFE3 120 osnewl=&FFE7 130 oscli=&FFF7 140 FOR pass = 0 TO 2 STEP 2 150 P%=HIMEM 160 [ OPT pass 170 BRK 180 BRK 190 BRK 200 JMP service+diff 210 OPT FNequb(&82) 220 OPT FNequb((copyright+diff) MOD 256) 230 BRK 240 .title 250 OPT FNequs("PEEK") 260 .copyright 270 BRK 280 OPT FNequs("(C) Gordon Horsington 1987") 290 BRK 300 .service 310 CMP #4 320 BEQ unrecognised 330 RTS 340 .unrecognised 350 PHA 360 TXA 370 PHA 380 TYA 390 PHA 400 LDX #&FF 410 .comloop 420 INX 430 LDA title+diff,X 440 BEQ found 450 LDA (comvec),Y 460 INY 470 CMP #ASC(".") 480 BEQ found 490 AND #&DF 500 CMP title+diff,X 510 BEQ comloop 520 PLA 530 TAY 540 PLA 550 TAX 560 PLA 570 RTS 580 .found 590 CLC 600 JSR gsinit 610 LDA address 620 PHA 630 LDA address+1 640 PHA 650 LDX #0 660 STX address 670 STX address+1 680 DEX 690 .argloop 700 JSR gsread 710 BCS endarg 720 CMP #ASC("&") 730 BEQ argloop 740 JSR convert+diff 750 PHA \ Push hex nybbles 760 INX 770 BPL argloop 780 .endarg 790 CPX #4 800 BCS error 810 PLA \ LS nybble low byte 820 STA address 830 DEX 840 BMI finish 850 PLA \ MS nybble low byte 860 ASL A 870 ASL A 880 ASL A 890 ASL A 900 ORA address 910 STA address \ LS byte 920 DEX 930 BMI finish 940 PLA \ LS nybble high byte 950 STA address+1 960 DEX 970 BMI finish 980 PLA \ MS nybble high byte 990 ASL A 1000 ASL A 1010 ASL A 1020 ASL A 1030 ORA address+1 1040 STA address+1 \ MS byte 1050 .finish 1060 LDY #0 1070 LDA (address),Y 1080 JSR hexbyte+diff 1090 JSR osnewl 1100 PLA 1110 STA address+1 1120 PLA 1130 STA address 1140 PLA 1150 PLA 1160 PLA 1170 LDA #0 1180 RTS 1190 .hexbyte 1200 PHA 1210 LSR A 1220 LSR A 1230 LSR A 1240 LSR A 1250 JSR nybble+diff 1260 PLA 1270 .nybble 1280 AND #&F 1290 SED 1300 CLC 1310 ADC #&90 1320 ADC #&40 1330 CLD 1340 JMP osasci 1350 .convert 1360 CMP #ASC("9")+1 1370 BCS letters 1380 CMP #ASC("0") 1390 BMI error 1400 AND #&F 1410 RTS 1420 .letters 1430 SBC #&37 1440 CMP #&A 1450 BMI error 1460 CMP #&10 1470 BCS error 1480 RTS 1490 .error 1500 LDA #(errormsg+diff) MOD 256 1510 STA address 1520 LDA #(errormsg+diff) DIV 256 1530 STA address+1 1540 LDY #&FF 1550 .errorloop 1560 INY 1570 LDA (address),Y 1580 STA errstack,Y 1590 BPL errorloop 1600 JMP errstack 1610 .errormsg 1620 BRK 1630 BRK 1640 OPT FNequs("Out of range") 1650 BRK 1660 OPT FNequb(&FF) 1670 .lastbyte 1680 ] 1690 NEXT 1700 INPUT'"Save filename = "filename$ 1710 IF filename$="" END 1720 $save="SAVE "+filename$+" "+STR$~(HIMEM)+" "+STR$~(las tbyte)+" FFFF8000 FFFF8000" 1730 X%=save MOD 256 1740 Y%=save DIV 256 1750 *OPT1,2 1760 CALL oscli 1770 *OPT1,0 1780 END 1790 DEFFNequb(byte) 1800 ?P%=byte 1810 P%=P%+1 1820 =pass 1830 DEFFNequw(word) 1840 ?P%=word MOD 256 1850 P%?1=word DIV 256 1860 P%=P%+2 1870 =pass 1880 DEFFNequd(double) 1890 !P%=double 1900 P%=P%+4 1910 =pass 1920 DEFFNequs(string$) 1930 $P%=string$ 1940 P%=P%+LEN(string$) 1950 =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 39 20 2d 20 4e 75 6d 65 72 |odule 09 - Numer| 00000030 69 63 61 6c 20 61 72 67 75 6d 65 6e 74 73 0d 2d |ical arguments.-| 00000040 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------| * 00000070 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0d 0d 20 |-------------.. | 00000080 20 49 6e 20 6d 6f 64 75 6c 65 73 20 36 20 61 6e | In modules 6 an| 00000090 64 20 37 20 79 6f 75 20 77 65 72 65 20 73 68 6f |d 7 you were sho| 000000a0 77 6e 20 68 6f 77 20 74 6f 20 75 73 65 20 74 68 |wn how to use th| 000000b0 65 20 4d 4f 53 20 74 6f 20 72 65 61 64 0d 6e 75 |e MOS to read.nu| 000000c0 6d 65 72 69 63 61 6c 20 61 72 67 75 6d 65 6e 74 |merical argument| 000000d0 73 20 62 79 20 64 65 66 69 6e 69 6e 67 20 6e 65 |s by defining ne| 000000e0 77 20 4f 73 62 79 74 65 20 61 6e 64 20 4f 73 77 |w Osbyte and Osw| 000000f0 6f 72 64 20 72 6f 75 74 69 6e 65 73 2e 20 49 6e |ord routines. In| 00000100 0d 74 68 69 73 20 6d 6f 64 75 6c 65 20 49 20 77 |.this module I w| 00000110 69 6c 6c 20 73 68 6f 77 20 79 6f 75 20 6f 6e 65 |ill show you one| 00000120 20 77 61 79 20 6f 66 20 72 65 61 64 69 6e 67 20 | way of reading | 00000130 6e 75 6d 65 72 69 63 61 6c 20 61 72 67 75 6d 65 |numerical argume| 00000140 6e 74 73 20 61 6e 64 0d 63 6f 6e 76 65 72 74 69 |nts and.converti| 00000150 6e 67 20 74 68 65 6d 20 69 6e 74 6f 20 62 69 6e |ng them into bin| 00000160 61 72 79 2e 0d 0d 20 20 54 68 65 72 65 20 69 73 |ary... There is| 00000170 20 6e 6f 20 6f 6e 65 20 63 6f 72 72 65 63 74 20 | no one correct | 00000180 77 61 79 20 6f 66 20 72 65 61 64 69 6e 67 20 6e |way of reading n| 00000190 75 6d 65 72 69 63 61 6c 20 61 72 67 75 6d 65 6e |umerical argumen| 000001a0 74 73 20 61 6e 64 2c 20 61 73 0d 77 69 74 68 20 |ts and, as.with | 000001b0 6d 6f 73 74 20 70 72 6f 67 72 61 6d 6d 69 6e 67 |most programming| 000001c0 20 70 72 6f 62 6c 65 6d 73 2c 20 74 68 65 72 65 | problems, there| 000001d0 20 61 72 65 20 61 73 20 6d 61 6e 79 20 73 6f 6c | are as many sol| 000001e0 75 74 69 6f 6e 73 20 61 73 20 74 68 65 72 65 0d |utions as there.| 000001f0 61 72 65 20 70 65 6f 70 6c 65 20 74 6f 20 77 72 |are people to wr| 00000200 69 74 65 20 74 68 65 6d 2e 20 54 68 65 20 6d 65 |ite them. The me| 00000210 74 68 6f 64 20 49 20 77 69 6c 6c 20 64 65 6d 6f |thod I will demo| 00000220 6e 73 74 72 61 74 65 20 69 73 20 71 75 69 74 65 |nstrate is quite| 00000230 0d 75 73 65 66 75 6c 20 66 6f 72 20 73 69 64 65 |.useful for side| 00000240 77 61 79 73 20 72 61 6d 20 70 72 6f 67 72 61 6d |ways ram program| 00000250 73 20 62 65 63 61 75 73 65 20 69 74 20 75 73 65 |s because it use| 00000260 73 20 74 68 65 20 6d 69 6e 69 6d 75 6d 20 61 6d |s the minimum am| 00000270 6f 75 6e 74 20 6f 66 0d 75 73 65 72 20 6d 65 6d |ount of.user mem| 00000280 6f 72 79 20 61 6e 64 20 72 65 73 74 6f 72 65 73 |ory and restores| 00000290 20 74 68 61 74 20 6d 65 6d 6f 72 79 20 61 66 74 | that memory aft| 000002a0 65 72 20 75 73 65 2e 0d 0d 20 20 54 68 65 20 6d |er use... The m| 000002b0 65 74 68 6f 64 20 64 65 6d 6f 6e 73 74 72 61 74 |ethod demonstrat| 000002c0 65 64 20 69 6e 20 74 68 69 73 20 6d 6f 64 75 6c |ed in this modul| 000002d0 65 20 77 69 6c 6c 20 72 65 61 64 20 61 20 68 65 |e will read a he| 000002e0 78 61 64 65 63 69 6d 61 6c 0d 61 72 67 75 6d 65 |xadecimal.argume| 000002f0 6e 74 20 69 6e 20 74 68 65 20 72 61 6e 67 65 20 |nt in the range | 00000300 66 72 6f 6d 20 26 30 30 20 74 6f 20 26 46 46 46 |from &00 to &FFF| 00000310 46 20 61 6e 64 20 63 6f 6e 76 65 72 74 20 74 68 |F and convert th| 00000320 65 20 61 72 67 75 6d 65 6e 74 20 69 6e 74 6f 0d |e argument into.| 00000330 61 20 74 77 6f 20 62 79 74 65 20 62 69 6e 61 72 |a two byte binar| 00000340 79 20 6e 75 6d 62 65 72 2e 20 54 68 65 20 72 6f |y number. The ro| 00000350 75 74 69 6e 65 20 69 6e 63 6c 75 64 65 73 20 72 |utine includes r| 00000360 61 6e 67 65 20 61 6e 64 20 65 72 72 6f 72 0d 63 |ange and error.c| 00000370 68 65 63 6b 69 6e 67 20 74 6f 20 65 78 63 6c 75 |hecking to exclu| 00000380 64 65 20 69 6e 76 61 6c 69 64 20 63 68 61 72 61 |de invalid chara| 00000390 63 74 65 72 73 2e 20 54 68 65 20 62 69 6e 61 72 |cters. The binar| 000003a0 79 20 72 65 70 72 65 73 65 6e 74 61 74 69 6f 6e |y representation| 000003b0 20 6f 66 0d 74 68 65 20 61 72 67 75 6d 65 6e 74 | of.the argument| 000003c0 20 69 73 20 73 74 6f 72 65 64 20 69 6e 20 74 77 | is stored in tw| 000003d0 6f 20 62 79 74 65 73 20 6f 66 20 7a 65 72 6f 20 |o bytes of zero | 000003e0 70 61 67 65 20 6d 65 6d 6f 72 79 20 72 65 61 64 |page memory read| 000003f0 79 20 74 6f 20 62 65 0d 75 73 65 64 20 62 79 20 |y to be.used by | 00000400 74 68 65 20 72 65 73 74 20 6f 66 20 74 68 65 20 |the rest of the | 00000410 72 6f 75 74 69 6e 65 2e 20 54 68 65 73 65 20 74 |routine. These t| 00000420 77 6f 20 62 79 74 65 73 20 63 61 6e 20 62 65 20 |wo bytes can be | 00000430 72 65 73 74 6f 72 65 64 0d 62 65 66 6f 72 65 20 |restored.before | 00000440 72 65 74 75 72 6e 69 6e 67 20 66 72 6f 6d 20 74 |returning from t| 00000450 68 65 20 72 6f 6d 2e 0d 0d 20 20 57 68 65 6e 20 |he rom... When | 00000460 79 6f 75 20 64 65 73 69 67 6e 20 79 6f 75 72 20 |you design your | 00000470 53 57 52 20 70 72 6f 67 72 61 6d 73 20 79 6f 75 |SWR programs you| 00000480 20 73 68 6f 75 6c 64 20 61 6e 74 69 63 69 70 61 | should anticipa| 00000490 74 65 20 68 6f 77 20 74 68 65 79 0d 77 69 6c 6c |te how they.will| 000004a0 20 62 65 20 75 73 65 64 2e 20 49 66 20 74 68 65 | be used. If the| 000004b0 20 69 6e 73 74 72 75 63 74 69 6f 6e 73 20 66 6f | instructions fo| 000004c0 72 20 75 73 69 6e 67 20 79 6f 75 72 20 70 72 6f |r using your pro| 000004d0 67 72 61 6d 20 74 65 6c 6c 20 74 68 65 20 75 73 |gram tell the us| 000004e0 65 72 0d 74 6f 20 65 6e 74 65 72 2c 20 66 6f 72 |er.to enter, for| 000004f0 20 65 78 61 6d 70 6c 65 2c 20 74 68 65 20 68 65 | example, the he| 00000500 78 61 64 65 63 69 6d 61 6c 20 61 72 67 75 6d 65 |xadecimal argume| 00000510 6e 74 20 6f 6e 65 2d 74 77 6f 2d 74 68 72 65 65 |nt one-two-three| 00000520 2c 20 79 6f 75 72 0d 70 72 6f 67 72 61 6d 20 73 |, your.program s| 00000530 68 6f 75 6c 64 20 72 65 63 6f 67 6e 69 73 65 20 |hould recognise | 00000540 26 31 32 33 20 26 30 31 32 33 20 31 32 33 20 61 |&123 &0123 123 a| 00000550 6e 64 20 30 31 32 33 20 61 73 20 61 6c 6c 20 74 |nd 0123 as all t| 00000560 68 65 20 73 61 6d 65 2c 0d 63 6f 72 72 65 63 74 |he same,.correct| 00000570 2c 20 61 72 67 75 6d 65 6e 74 2e 20 59 6f 75 72 |, argument. Your| 00000580 20 70 72 6f 67 72 61 6d 20 73 68 6f 75 6c 64 20 | program should | 00000590 6e 6f 74 20 69 6e 73 69 73 74 20 6f 6e 20 75 73 |not insist on us| 000005a0 69 6e 67 20 6c 65 61 64 69 6e 67 0d 7a 65 72 6f |ing leading.zero| 000005b0 73 20 6f 72 20 61 6e 20 61 6d 70 65 72 73 61 6e |s or an ampersan| 000005c0 64 20 28 26 29 20 70 72 65 66 69 78 20 69 66 20 |d (&) prefix if | 000005d0 61 20 68 65 78 61 64 65 63 69 6d 61 6c 20 6e 75 |a hexadecimal nu| 000005e0 6d 62 65 72 20 69 73 20 65 78 70 65 63 74 65 64 |mber is expected| 000005f0 0d 62 75 74 20 69 74 20 73 68 6f 75 6c 64 20 61 |.but it should a| 00000600 63 63 65 70 74 20 74 68 65 6d 20 77 69 74 68 6f |ccept them witho| 00000610 75 74 20 67 65 6e 65 72 61 74 69 6e 67 20 61 6e |ut generating an| 00000620 20 65 72 72 6f 72 2e 0d 0d 20 20 49 74 20 69 73 | error... It is| 00000630 20 6e 6f 74 20 61 20 67 6f 6f 64 20 69 64 65 61 | not a good idea| 00000640 20 74 6f 20 67 65 74 20 79 6f 75 72 20 53 57 52 | to get your SWR| 00000650 20 70 72 6f 67 72 61 6d 20 72 75 6e 6e 69 6e 67 | program running| 00000660 20 77 69 74 68 20 61 20 2a 0d 63 6f 6d 6d 61 6e | with a *.comman| 00000670 64 2c 20 74 68 65 6e 20 70 72 6f 6d 70 74 20 66 |d, then prompt f| 00000680 6f 72 20 61 20 6e 75 6d 62 65 72 20 61 6e 64 20 |or a number and | 00000690 75 73 65 20 4f 73 72 64 63 68 20 74 6f 20 72 65 |use Osrdch to re| 000006a0 61 64 20 69 74 20 62 79 74 65 20 61 66 74 65 72 |ad it byte after| 000006b0 0d 62 79 74 65 2e 20 54 68 61 74 20 73 74 79 6c |.byte. That styl| 000006c0 65 20 6f 66 20 70 72 6f 67 72 61 6d 6d 69 6e 67 |e of programming| 000006d0 20 77 6f 72 6b 73 20 62 75 74 20 69 74 20 6c 6f | works but it lo| 000006e0 6f 6b 73 20 76 65 72 79 20 75 6e 70 72 6f 66 65 |oks very unprofe| 000006f0 73 73 69 6f 6e 61 6c 0d 61 6e 64 20 77 72 69 74 |ssional.and writ| 00000700 69 6e 67 20 61 20 70 72 6f 67 72 61 6d 20 77 68 |ing a program wh| 00000710 69 63 68 20 61 6c 6c 6f 77 73 20 74 68 65 20 75 |ich allows the u| 00000720 73 65 72 20 74 6f 20 65 64 69 74 20 74 68 65 20 |ser to edit the | 00000730 6e 75 6d 62 65 72 20 77 69 74 68 0d 74 68 65 20 |number with.the | 00000740 44 65 6c 65 74 65 20 6b 65 79 20 69 73 20 71 75 |Delete key is qu| 00000750 69 74 65 20 63 6f 6d 70 6c 69 63 61 74 65 64 2e |ite complicated.| 00000760 20 54 68 65 20 61 72 67 75 6d 65 6e 74 28 73 29 | The argument(s)| 00000770 20 73 68 6f 75 6c 64 20 66 6f 6c 6c 6f 77 20 74 | should follow t| 00000780 68 65 0d 63 6f 6d 6d 61 6e 64 20 73 6f 20 74 68 |he.command so th| 00000790 61 74 20 69 66 2c 20 66 6f 72 20 65 78 61 6d 70 |at if, for examp| 000007a0 6c 65 2c 20 79 6f 75 20 68 61 76 65 20 77 72 69 |le, you have wri| 000007b0 74 74 65 6e 20 61 20 70 72 6f 67 72 61 6d 20 77 |tten a program w| 000007c0 68 69 63 68 0d 70 72 69 6e 74 73 20 74 68 65 20 |hich.prints the | 000007d0 63 6f 6e 74 65 6e 74 73 20 6f 66 20 61 20 6d 65 |contents of a me| 000007e0 6d 6f 72 79 20 6c 6f 63 61 74 69 6f 6e 20 61 6e |mory location an| 000007f0 64 20 79 6f 75 20 77 61 6e 74 20 74 6f 20 75 73 |d you want to us| 00000800 65 20 69 74 20 74 6f 0d 70 72 69 6e 74 20 74 68 |e it to.print th| 00000810 65 20 63 6f 6e 74 65 6e 74 73 20 6f 66 20 6c 6f |e contents of lo| 00000820 63 61 74 69 6f 6e 20 26 39 30 30 20 79 6f 75 72 |cation &900 your| 00000830 20 53 57 52 20 69 6e 74 65 72 70 72 65 74 65 72 | SWR interpreter| 00000840 20 73 68 6f 75 6c 64 20 61 63 63 65 70 74 0d 61 | should accept.a| 00000850 6e 79 20 6f 66 20 74 68 65 20 63 6f 6d 6d 61 6e |ny of the comman| 00000860 64 73 20 69 6e 20 66 69 67 75 72 65 20 39 2e 31 |ds in figure 9.1| 00000870 20 74 6f 20 63 61 6c 6c 20 74 68 65 20 72 6f 75 | to call the rou| 00000880 74 69 6e 65 20 61 6e 64 20 70 72 69 6e 74 20 74 |tine and print t| 00000890 68 65 0d 61 6e 73 77 65 72 2e 0d 0d 0d 0d 0d 3e |he.answer......>| 000008a0 2a 50 45 45 4b 20 26 39 30 30 20 3c 52 65 74 75 |*PEEK &900 <Retu| 000008b0 72 6e 3e 0d 3e 2a 50 45 45 4b 20 26 30 39 30 30 |rn>.>*PEEK &0900| 000008c0 20 3c 52 65 74 75 72 6e 3e 0d 3e 2a 70 65 65 6b | <Return>.>*peek| 000008d0 20 22 39 30 30 22 20 3c 52 65 74 75 72 6e 3e 0d | "900" <Return>.| 000008e0 3e 2a 70 65 2e 20 30 39 30 30 20 3c 52 65 74 75 |>*pe. 0900 <Retu| 000008f0 72 6e 3e 0d 0d 46 69 67 75 72 65 20 39 2e 31 20 |rn>..Figure 9.1 | 00000900 20 56 61 6c 69 64 20 63 6f 6d 6d 61 6e 64 73 20 | Valid commands | 00000910 61 6e 64 20 61 72 67 75 6d 65 6e 74 73 0d 2d 2d |and arguments.--| 00000920 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------| * 00000940 2d 2d 2d 2d 2d 2d 0d 0d 0d 0d 0d 20 20 55 70 20 |------..... Up | 00000950 74 6f 20 66 6f 75 72 20 41 53 43 49 49 20 63 68 |to four ASCII ch| 00000960 61 72 61 63 74 65 72 73 20 63 61 6e 20 62 65 20 |aracters can be | 00000970 75 73 65 64 20 74 6f 20 72 65 70 72 65 73 65 6e |used to represen| 00000980 74 20 61 20 74 77 6f 20 62 79 74 65 0d 68 65 78 |t a two byte.hex| 00000990 61 64 65 63 69 6d 61 6c 20 6e 75 6d 62 65 72 2e |adecimal number.| 000009a0 20 54 68 65 20 6e 79 62 62 6c 65 20 72 65 70 72 | The nybble repr| 000009b0 65 73 65 6e 74 65 64 20 62 79 20 74 68 65 20 66 |esented by the f| 000009c0 69 72 73 74 20 41 53 43 49 49 0d 63 68 61 72 61 |irst ASCII.chara| 000009d0 63 74 65 72 20 64 65 70 65 6e 64 73 20 6f 6e 20 |cter depends on | 000009e0 68 6f 77 20 6d 61 6e 79 20 63 68 61 72 61 63 74 |how many charact| 000009f0 65 72 73 20 61 72 65 20 75 73 65 64 20 74 6f 20 |ers are used to | 00000a00 72 65 70 72 65 73 65 6e 74 20 74 68 65 0d 6e 75 |represent the.nu| 00000a10 6d 62 65 72 2e 20 46 6f 72 20 65 78 61 6d 70 6c |mber. For exampl| 00000a20 65 2c 20 74 68 65 20 41 20 69 6e 20 26 41 42 20 |e, the A in &AB | 00000a30 72 65 70 72 65 73 65 6e 74 73 20 74 68 65 20 6d |represents the m| 00000a40 6f 73 74 20 73 69 67 6e 69 66 69 63 61 6e 74 0d |ost significant.| 00000a50 6e 79 62 62 6c 65 20 6f 66 20 74 68 65 20 6c 65 |nybble of the le| 00000a60 61 73 74 20 73 69 67 6e 69 66 69 63 61 6e 74 20 |ast significant | 00000a70 62 79 74 65 20 62 75 74 20 74 68 65 20 41 20 69 |byte but the A i| 00000a80 6e 20 26 41 42 43 20 72 65 70 72 65 73 65 6e 74 |n &ABC represent| 00000a90 73 20 74 68 65 0d 6c 65 61 73 74 20 73 69 67 6e |s the.least sign| 00000aa0 69 66 69 63 61 6e 74 20 6e 79 62 62 6c 65 20 6f |ificant nybble o| 00000ab0 66 20 74 68 65 20 6d 6f 73 74 20 73 69 67 6e 69 |f the most signi| 00000ac0 66 69 63 61 6e 74 20 62 79 74 65 2e 0d 0d 20 20 |ficant byte... | 00000ad0 49 66 20 79 6f 75 20 72 65 61 64 20 74 68 65 20 |If you read the | 00000ae0 41 53 43 49 49 20 63 68 61 72 61 63 74 65 72 73 |ASCII characters| 00000af0 20 66 72 6f 6d 20 72 69 67 68 74 20 74 6f 20 6c | from right to l| 00000b00 65 66 74 2c 20 69 6e 73 74 65 61 64 20 6f 66 20 |eft, instead of | 00000b10 74 68 65 0d 6d 6f 72 65 20 6e 61 74 75 72 61 6c |the.more natural| 00000b20 20 6c 65 66 74 20 74 6f 20 72 69 67 68 74 2c 20 | left to right, | 00000b30 74 68 65 20 66 69 72 73 74 20 62 79 74 65 20 79 |the first byte y| 00000b40 6f 75 20 72 65 61 64 20 77 69 6c 6c 20 61 6c 77 |ou read will alw| 00000b50 61 79 73 20 62 65 20 74 68 65 0d 6c 65 61 73 74 |ays be the.least| 00000b60 20 73 69 67 6e 69 66 69 63 61 6e 74 20 6e 79 62 | significant nyb| 00000b70 62 6c 65 20 6f 66 20 74 68 65 20 6c 65 61 73 74 |ble of the least| 00000b80 20 73 69 67 6e 69 66 69 63 61 6e 74 20 62 79 74 | significant byt| 00000b90 65 2e 20 49 66 20 79 6f 75 20 72 65 61 64 0d 74 |e. If you read.t| 00000ba0 68 65 20 63 68 61 72 61 63 74 65 72 73 20 66 72 |he characters fr| 00000bb0 6f 6d 20 6c 65 66 74 20 74 6f 20 72 69 67 68 74 |om left to right| 00000bc0 20 79 6f 75 20 65 69 74 68 65 72 20 68 61 76 65 | you either have| 00000bd0 20 74 6f 20 6b 6e 6f 77 20 69 6e 20 61 64 76 61 | to know in adva| 00000be0 6e 63 65 0d 68 6f 77 20 6d 61 6e 79 20 63 68 61 |nce.how many cha| 00000bf0 72 61 63 74 65 72 73 20 61 72 65 20 75 73 65 64 |racters are used| 00000c00 20 73 6f 20 74 68 61 74 2c 20 69 66 20 6e 65 63 | so that, if nec| 00000c10 65 73 73 61 72 79 2c 20 79 6f 75 20 63 61 6e 20 |essary, you can | 00000c20 70 61 64 20 6f 75 74 0d 74 68 65 20 6e 75 6d 62 |pad out.the numb| 00000c30 65 72 20 77 69 74 68 20 6c 65 61 64 69 6e 67 20 |er with leading | 00000c40 7a 65 72 6f 73 20 6f 72 20 79 6f 75 20 68 61 76 |zeros or you hav| 00000c50 65 20 74 6f 20 74 79 70 65 20 74 68 65 20 6c 65 |e to type the le| 00000c60 61 64 69 6e 67 20 7a 65 72 6f 73 20 74 6f 0d 65 |ading zeros to.e| 00000c70 73 74 61 62 6c 69 73 68 20 74 68 65 20 70 6c 61 |stablish the pla| 00000c80 63 65 20 76 61 6c 75 65 20 6f 66 20 65 61 63 68 |ce value of each| 00000c90 20 63 68 61 72 61 63 74 65 72 20 69 6e 20 74 68 | character in th| 00000ca0 65 20 61 72 67 75 6d 65 6e 74 2e 0d 0d 20 20 54 |e argument... T| 00000cb0 6f 20 63 6f 6e 76 65 72 74 20 74 68 65 20 41 53 |o convert the AS| 00000cc0 43 49 49 20 72 65 70 72 65 73 65 6e 74 61 74 69 |CII representati| 00000cd0 6f 6e 20 6f 66 20 61 20 68 65 78 61 64 65 63 69 |on of a hexadeci| 00000ce0 6d 61 6c 20 61 72 67 75 6d 65 6e 74 20 69 6e 74 |mal argument int| 00000cf0 6f 0d 62 69 6e 61 72 79 20 79 6f 75 20 73 68 6f |o.binary you sho| 00000d00 75 6c 64 20 73 74 61 72 74 20 77 69 74 68 20 74 |uld start with t| 00000d10 68 65 20 6c 65 61 73 74 20 73 69 67 6e 69 66 69 |he least signifi| 00000d20 63 61 6e 74 20 6e 79 62 62 6c 65 20 6f 66 20 74 |cant nybble of t| 00000d30 68 65 20 6c 65 61 73 74 0d 73 69 67 6e 69 66 69 |he least.signifi| 00000d40 63 61 6e 74 20 62 79 74 65 20 75 6e 6c 65 73 73 |cant byte unless| 00000d50 20 79 6f 75 20 75 73 65 20 61 6e 20 65 6c 61 62 | you use an elab| 00000d60 6f 72 61 74 65 20 63 6f 6e 76 65 72 73 69 6f 6e |orate conversion| 00000d70 20 61 6c 67 6f 72 69 74 68 6d 20 6f 72 0d 6c 65 | algorithm or.le| 00000d80 61 64 69 6e 67 20 7a 65 72 6f 73 2e 20 54 68 69 |ading zeros. Thi| 00000d90 73 20 70 72 65 73 65 6e 74 73 20 61 20 70 72 6f |s presents a pro| 00000da0 62 6c 65 6d 20 62 65 63 61 75 73 65 20 74 68 65 |blem because the| 00000db0 20 47 73 72 65 61 64 20 72 6f 75 74 69 6e 65 20 | Gsread routine | 00000dc0 75 73 65 64 0d 74 6f 20 72 65 61 64 20 74 68 65 |used.to read the| 00000dd0 20 41 53 43 49 49 20 63 68 61 72 61 63 74 65 72 | ASCII character| 00000de0 73 20 66 72 6f 6d 20 74 68 65 20 61 72 67 75 6d |s from the argum| 00000df0 65 6e 74 20 72 65 61 64 73 20 66 72 6f 6d 20 6c |ent reads from l| 00000e00 65 66 74 20 74 6f 0d 72 69 67 68 74 2e 20 54 6f |eft to.right. To| 00000e10 20 67 65 74 20 72 6f 75 6e 64 20 74 68 69 73 20 | get round this | 00000e20 70 72 6f 62 6c 65 6d 20 79 6f 75 20 63 61 6e 20 |problem you can | 00000e30 72 65 61 64 20 65 61 63 68 20 6e 79 62 62 6c 65 |read each nybble| 00000e40 20 6f 66 20 74 68 65 0d 61 72 67 75 6d 65 6e 74 | of the.argument| 00000e50 2c 20 63 6f 6e 76 65 72 74 20 69 74 20 69 6e 74 |, convert it int| 00000e60 6f 20 62 69 6e 61 72 79 20 61 6e 64 20 70 75 73 |o binary and pus| 00000e70 68 20 69 74 20 6f 6e 20 74 68 65 20 73 74 61 63 |h it on the stac| 00000e80 6b 20 75 6e 74 69 6c 20 79 6f 75 0d 72 65 61 64 |k until you.read| 00000e90 20 74 68 65 20 74 65 72 6d 69 6e 61 74 69 6f 6e | the termination| 00000ea0 20 63 68 61 72 61 63 74 65 72 2e 20 54 68 65 6e | character. Then| 00000eb0 20 70 75 6c 6c 20 65 61 63 68 20 6e 79 62 62 6c | pull each nybbl| 00000ec0 65 20 6f 66 66 20 74 68 65 20 73 74 61 63 6b 0d |e off the stack.| 00000ed0 61 6e 64 20 74 68 65 79 20 77 69 6c 6c 20 62 65 |and they will be| 00000ee0 20 69 6e 20 72 65 76 65 72 73 65 20 6f 72 64 65 | in reverse orde| 00000ef0 72 2c 20 61 73 20 69 66 20 74 68 65 79 20 68 61 |r, as if they ha| 00000f00 64 20 62 65 65 6e 20 72 65 61 64 20 66 72 6f 6d |d been read from| 00000f10 20 72 69 67 68 74 0d 74 6f 20 6c 65 66 74 2e 0d | right.to left..| 00000f20 0d 20 20 49 66 20 79 6f 75 20 6b 65 65 70 20 61 |. If you keep a| 00000f30 20 63 6f 75 6e 74 20 6f 66 20 74 68 65 20 6e 75 | count of the nu| 00000f40 6d 62 65 72 20 6f 66 20 6e 79 62 62 6c 65 73 20 |mber of nybbles | 00000f50 72 65 61 64 20 66 72 6f 6d 20 74 68 65 20 61 72 |read from the ar| 00000f60 67 75 6d 65 6e 74 0d 69 74 20 69 73 20 61 20 73 |gument.it is a s| 00000f70 69 6d 70 6c 65 20 6d 61 74 74 65 72 20 74 6f 20 |imple matter to | 00000f80 70 75 6c 6c 20 74 68 65 20 6e 79 62 62 6c 65 73 |pull the nybbles| 00000f90 20 6f 66 66 20 74 68 65 20 73 74 61 63 6b 20 61 | off the stack a| 00000fa0 6e 64 20 63 6f 6e 76 65 72 74 0d 65 61 63 68 20 |nd convert.each | 00000fb0 6e 79 62 62 6c 65 2c 20 6f 72 20 70 61 69 72 20 |nybble, or pair | 00000fc0 6f 66 20 6e 79 62 62 6c 65 73 2c 20 69 6e 74 6f |of nybbles, into| 00000fd0 20 61 20 62 79 74 65 2e 20 54 68 69 73 20 74 65 | a byte. This te| 00000fe0 63 68 6e 69 71 75 65 20 69 73 0d 69 6c 6c 75 73 |chnique is.illus| 00000ff0 74 72 61 74 65 64 20 69 6e 20 66 69 67 75 72 65 |trated in figure| 00001000 20 39 2e 32 2e 0d 0d 0d 0d 0d 2e 66 6f 75 6e 64 | 9.2.......found| 00001010 0d 20 20 20 20 20 20 20 20 43 4c 43 20 20 20 20 |. CLC | 00001020 20 20 20 20 20 20 20 5c 20 74 65 72 6d 69 6e 61 | \ termina| 00001030 74 65 20 77 69 74 68 20 73 70 61 63 65 2c 20 72 |te with space, r| 00001040 65 74 75 72 6e 20 6f 72 20 22 0d 20 20 20 20 20 |eturn or ". | 00001050 20 20 20 4a 53 52 20 26 46 46 43 32 20 20 20 20 | JSR &FFC2 | 00001060 20 5c 20 69 6e 69 74 69 61 6c 69 73 65 20 61 72 | \ initialise ar| 00001070 67 75 6d 65 6e 74 20 77 69 74 68 20 47 73 69 6e |gument with Gsin| 00001080 69 74 0d 20 20 20 20 20 20 20 20 4c 44 58 20 23 |it. LDX #| 00001090 30 20 20 20 20 20 20 20 20 5c 20 69 6e 69 74 69 |0 \ initi| 000010a0 61 6c 20 72 65 73 75 6c 74 20 3d 20 26 30 30 30 |al result = &000| 000010b0 30 0d 20 20 20 20 20 20 20 20 53 54 58 20 26 37 |0. STX &7| 000010c0 30 20 20 20 20 20 20 20 5c 20 6c 65 61 73 74 20 |0 \ least | 000010d0 73 69 67 2e 20 62 79 74 65 20 6f 66 20 72 65 73 |sig. byte of res| 000010e0 75 6c 74 0d 20 20 20 20 20 20 20 20 53 54 58 20 |ult. STX | 000010f0 26 37 31 20 20 20 20 20 20 20 5c 20 6d 6f 73 74 |&71 \ most| 00001100 20 73 69 67 2e 20 62 79 74 65 20 6f 66 20 72 65 | sig. byte of re| 00001110 73 75 6c 74 0d 20 20 20 20 20 20 20 20 44 45 58 |sult. DEX| 00001120 20 20 20 20 20 20 20 20 20 20 20 5c 20 58 20 77 | \ X w| 00001130 69 6c 6c 20 63 6f 75 6e 74 20 6e 75 6d 62 65 72 |ill count number| 00001140 20 6f 66 20 6e 79 62 62 6c 65 73 20 2d 20 31 0d | of nybbles - 1.| 00001150 2e 61 72 67 6c 6f 6f 70 0d 20 20 20 20 20 20 20 |.argloop. | 00001160 20 4a 53 52 20 26 46 46 43 35 20 20 20 20 20 5c | JSR &FFC5 \| 00001170 20 72 65 61 64 20 63 68 61 72 61 63 74 65 72 20 | read character | 00001180 66 72 6f 6d 20 61 72 67 75 6d 65 6e 74 20 77 69 |from argument wi| 00001190 74 68 20 47 73 72 65 61 64 0d 20 20 20 20 20 20 |th Gsread. | 000011a0 20 20 42 43 53 20 65 6e 64 61 72 67 20 20 20 20 | BCS endarg | 000011b0 5c 20 62 72 61 6e 63 68 20 69 66 20 74 65 72 6d |\ branch if term| 000011c0 69 6e 61 74 69 6f 6e 20 63 68 61 72 61 63 74 65 |ination characte| 000011d0 72 0d 20 20 20 20 20 20 20 20 43 4d 50 20 23 41 |r. CMP #A| 000011e0 53 43 28 22 26 22 29 20 5c 20 69 73 20 69 74 20 |SC("&") \ is it | 000011f0 22 26 22 3f 0d 20 20 20 20 20 20 20 20 42 45 51 |"&"?. BEQ| 00001200 20 61 72 67 6c 6f 6f 70 20 20 20 5c 20 69 67 6e | argloop \ ign| 00001210 6f 72 65 20 22 26 22 0d 20 20 20 20 20 20 20 20 |ore "&". | 00001220 4a 53 52 20 63 6f 6e 76 65 72 74 20 20 20 5c 20 |JSR convert \ | 00001230 63 6f 6e 76 65 72 74 20 6e 79 62 62 6c 65 20 69 |convert nybble i| 00001240 6e 74 6f 20 62 69 6e 61 72 79 0d 20 20 20 20 20 |nto binary. | 00001250 20 20 20 50 48 41 20 20 20 20 20 20 20 20 20 20 | PHA | 00001260 20 5c 20 70 75 73 68 20 6e 79 62 62 6c 65 20 6f | \ push nybble o| 00001270 6e 20 73 74 61 63 6b 0d 20 20 20 20 20 20 20 20 |n stack. | 00001280 49 4e 58 20 20 20 20 20 20 20 20 20 20 20 5c 20 |INX \ | 00001290 63 6f 75 6e 74 20 6e 79 62 62 6c 65 20 69 6e 20 |count nybble in | 000012a0 58 20 72 65 67 69 73 74 65 72 0d 20 20 20 20 20 |X register. | 000012b0 20 20 20 42 50 4c 20 61 72 67 6c 6f 6f 70 20 20 | BPL argloop | 000012c0 20 5c 20 62 72 61 6e 63 68 20 66 6f 72 20 6e 65 | \ branch for ne| 000012d0 78 74 20 63 68 61 72 61 63 74 65 72 0d 2e 65 6e |xt character..en| 000012e0 64 61 72 67 0d 20 20 20 20 20 20 20 20 43 50 58 |darg. CPX| 000012f0 20 23 34 20 20 20 20 20 20 20 20 5c 20 6d 6f 72 | #4 \ mor| 00001300 65 20 74 68 61 6e 20 34 20 63 68 61 72 61 63 74 |e than 4 charact| 00001310 65 72 73 3f 0d 20 20 20 20 20 20 20 20 42 43 53 |ers?. BCS| 00001320 20 65 72 72 6f 72 20 20 20 20 20 5c 20 62 72 61 | error \ bra| 00001330 6e 63 68 20 69 66 20 74 6f 6f 20 6d 61 6e 79 0d |nch if too many.| 00001340 20 20 20 20 20 20 20 20 50 4c 41 20 20 20 20 20 | PLA | 00001350 20 20 20 20 20 20 5c 20 70 75 6c 6c 20 4c 53 20 | \ pull LS | 00001360 6e 79 62 62 6c 65 20 6f 66 20 4c 53 20 62 79 74 |nybble of LS byt| 00001370 65 0d 20 20 20 20 20 20 20 20 53 54 41 20 26 37 |e. STA &7| 00001380 30 20 20 20 20 20 20 20 5c 20 73 74 6f 72 65 20 |0 \ store | 00001390 61 73 20 4c 53 20 62 79 74 65 0d 20 20 20 20 20 |as LS byte. | 000013a0 20 20 20 44 45 58 20 20 20 20 20 20 20 20 20 20 | DEX | 000013b0 20 5c 20 69 73 20 74 68 61 74 20 74 68 65 20 6f | \ is that the o| 000013c0 6e 6c 79 20 6e 79 62 62 6c 65 3f 0d 20 20 20 20 |nly nybble?. | 000013d0 20 20 20 20 42 4d 49 20 66 69 6e 69 73 68 20 20 | BMI finish | 000013e0 20 20 5c 20 62 72 61 6e 63 68 20 69 66 20 69 74 | \ branch if it| 000013f0 20 69 73 0d 20 20 20 20 20 20 20 20 50 4c 41 20 | is. PLA | 00001400 20 20 20 20 20 20 20 20 20 20 5c 20 70 75 6c 6c | \ pull| 00001410 20 4d 53 20 6e 79 62 62 6c 65 20 6f 66 20 4c 53 | MS nybble of LS| 00001420 20 62 79 74 65 0d 20 20 20 20 20 20 20 20 41 53 | byte. AS| 00001430 4c 20 41 20 20 20 20 20 20 20 20 20 5c 20 73 68 |L A \ sh| 00001440 69 66 74 0d 20 20 20 20 20 20 20 20 41 53 4c 20 |ift. ASL | 00001450 41 20 20 20 20 20 20 20 20 20 5c 20 6c 65 66 74 |A \ left| 00001460 0d 20 20 20 20 20 20 20 20 41 53 4c 20 41 20 20 |. ASL A | 00001470 20 20 20 20 20 20 20 5c 20 66 6f 75 72 0d 20 20 | \ four. | 00001480 20 20 20 20 20 20 41 53 4c 20 41 20 20 20 20 20 | ASL A | 00001490 20 20 20 20 5c 20 62 69 74 73 0d 20 20 20 20 20 | \ bits. | 000014a0 20 20 20 4f 52 41 20 26 37 30 20 20 20 20 20 20 | ORA &70 | 000014b0 20 5c 20 4f 52 20 77 69 74 68 20 26 37 30 0d 20 | \ OR with &70. | 000014c0 20 20 20 20 20 20 20 53 54 41 20 26 37 30 20 20 | STA &70 | 000014d0 20 20 20 20 20 5c 20 61 6e 64 20 73 74 6f 72 65 | \ and store| 000014e0 20 4c 53 20 62 79 74 65 0d 20 20 20 20 20 20 20 | LS byte. | 000014f0 20 44 45 58 20 20 20 20 20 20 20 20 20 20 20 5c | DEX \| 00001500 20 77 61 73 20 74 68 61 74 20 74 68 65 20 6c 61 | was that the la| 00001510 73 74 20 6e 79 62 62 6c 65 3f 0d 20 20 20 20 20 |st nybble?. | 00001520 20 20 20 42 4d 49 20 66 69 6e 69 73 68 20 20 20 | BMI finish | 00001530 20 5c 20 62 72 61 6e 63 68 20 69 66 20 69 74 20 | \ branch if it | 00001540 77 61 73 0d 20 20 20 20 20 20 20 20 50 4c 41 20 |was. PLA | 00001550 20 20 20 20 20 20 20 20 20 20 5c 20 70 75 6c 6c | \ pull| 00001560 20 4c 53 20 6e 79 62 62 6c 65 20 6f 66 20 4d 53 | LS nybble of MS| 00001570 20 62 79 74 65 0d 20 20 20 20 20 20 20 20 53 54 | byte. ST| 00001580 41 20 26 37 31 20 20 20 20 20 20 20 5c 20 73 74 |A &71 \ st| 00001590 6f 72 65 20 61 73 20 4d 53 20 62 79 74 65 0d 20 |ore as MS byte. | 000015a0 20 20 20 20 20 20 20 44 45 58 20 20 20 20 20 20 | DEX | 000015b0 20 20 20 20 20 5c 20 77 61 73 20 74 68 61 74 20 | \ was that | 000015c0 74 68 65 20 6c 61 73 74 20 6e 79 62 62 6c 65 3f |the last nybble?| 000015d0 0d 20 20 20 20 20 20 20 20 42 4d 49 20 66 69 6e |. BMI fin| 000015e0 69 73 68 20 20 20 20 5c 20 62 72 61 6e 63 68 20 |ish \ branch | 000015f0 69 66 20 69 74 20 77 61 73 0d 20 20 20 20 20 20 |if it was. | 00001600 20 20 50 4c 41 20 20 20 20 20 20 20 20 20 20 20 | PLA | 00001610 5c 20 70 75 6c 6c 20 4d 53 20 6e 79 62 62 6c 65 |\ pull MS nybble| 00001620 20 6f 66 20 4d 53 20 62 79 74 65 0d 20 20 20 20 | of MS byte. | 00001630 20 20 20 20 41 53 4c 20 41 20 20 20 20 20 20 20 | ASL A | 00001640 20 20 5c 20 73 68 69 66 74 0d 20 20 20 20 20 20 | \ shift. | 00001650 20 20 41 53 4c 20 41 20 20 20 20 20 20 20 20 20 | ASL A | 00001660 5c 20 6c 65 66 74 0d 20 20 20 20 20 20 20 20 41 |\ left. A| 00001670 53 4c 20 41 20 20 20 20 20 20 20 20 20 5c 20 66 |SL A \ f| 00001680 6f 75 72 0d 20 20 20 20 20 20 20 20 41 53 4c 20 |our. ASL | 00001690 41 20 20 20 20 20 20 20 20 20 5c 20 62 69 74 73 |A \ bits| 000016a0 0d 20 20 20 20 20 20 20 20 4f 52 41 20 26 37 31 |. ORA &71| 000016b0 20 20 20 20 20 20 20 5c 20 4f 52 20 77 69 74 68 | \ OR with| 000016c0 20 26 37 31 0d 20 20 20 20 20 20 20 20 53 54 41 | &71. STA| 000016d0 20 26 37 31 20 20 20 20 20 20 20 5c 20 61 6e 64 | &71 \ and| 000016e0 20 73 74 6f 72 65 20 4d 53 20 62 79 74 65 0d 2e | store MS byte..| 000016f0 66 69 6e 69 73 68 0d 0d 0d 46 69 67 75 72 65 20 |finish...Figure | 00001700 39 2e 32 20 20 43 6f 6e 76 65 72 74 69 6e 67 20 |9.2 Converting | 00001710 66 72 6f 6d 20 41 53 43 49 49 20 74 6f 20 62 69 |from ASCII to bi| 00001720 6e 61 72 79 0d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |nary.-----------| 00001730 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------| 00001740 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0d 0d |--------------..| 00001750 0d 0d 0d 20 20 41 66 74 65 72 20 72 65 63 6f 67 |... 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If an | 00002790 69 6e 76 61 6c 69 64 20 63 68 61 72 61 63 74 65 |invalid characte| 000027a0 72 0d 69 73 20 66 6f 75 6e 64 20 61 20 62 72 61 |r.is found a bra| 000027b0 6e 63 68 20 69 73 20 6d 61 64 65 20 74 6f 20 61 |nch is made to a| 000027c0 6e 20 65 72 72 6f 72 20 72 6f 75 74 69 6e 65 20 |n error routine | 000027d0 28 6c 69 6e 65 73 20 31 34 39 30 2d 31 36 36 30 |(lines 1490-1660| 000027e0 29 0d 73 69 6d 69 6c 61 72 20 74 6f 20 74 68 65 |).similar to the| 000027f0 20 6f 6e 65 20 69 6e 74 72 6f 64 75 63 65 64 20 | one introduced | 00002800 69 6e 20 4d 6f 64 75 6c 65 20 38 2e 0d 0d 20 20 |in Module 8... | 00002810 42 65 63 61 75 73 65 20 65 72 72 6f 72 73 20 63 |Because errors c| 00002820 61 6e 20 62 65 20 64 65 74 65 63 74 65 64 20 61 |an be detected a| 00002830 74 20 61 6e 79 20 73 74 61 67 65 20 6f 66 20 74 |t any stage of t| 00002840 68 65 20 63 6f 6e 76 65 72 73 69 6f 6e 2c 0d 72 |he conversion,.r| 00002850 65 73 74 6f 72 69 6e 67 20 74 68 65 20 7a 65 72 |estoring the zer| 00002860 6f 20 70 61 67 65 20 62 79 74 65 73 20 77 68 65 |o page bytes whe| 00002870 6e 20 61 6e 20 65 72 72 6f 72 20 69 73 20 66 6f |n an error is fo| 00002880 75 6e 64 20 77 6f 75 6c 64 20 61 64 64 20 65 78 |und would add ex| 00002890 74 72 61 0d 63 6f 6d 70 6c 69 63 61 74 69 6f 6e |tra.complication| 000028a0 73 20 74 6f 20 74 68 65 20 65 72 72 6f 72 20 72 |s to the error r| 000028b0 6f 75 74 69 6e 65 2e 20 41 6c 6c 20 74 68 65 20 |outine. All the | 000028c0 69 6e 66 6f 72 6d 61 74 69 6f 6e 20 79 6f 75 20 |information you | 000028d0 6e 65 65 64 20 74 6f 0d 72 65 73 74 6f 72 65 20 |need to.restore | 000028e0 74 68 65 20 7a 65 72 6f 20 70 61 67 65 20 62 79 |the zero page by| 000028f0 74 65 73 20 66 72 6f 6d 20 74 68 65 20 65 72 72 |tes from the err| 00002900 6f 72 20 72 6f 75 74 69 6e 65 20 69 73 20 61 76 |or routine is av| 00002910 61 69 6c 61 62 6c 65 20 69 6e 20 74 68 65 0d 58 |ailable in the.X| 00002920 20 72 65 67 69 73 74 65 72 2e 20 49 66 20 79 6f | register. If yo| 00002930 75 20 6e 65 65 64 20 74 68 65 20 65 78 65 72 63 |u need the exerc| 00002940 69 73 65 20 79 6f 75 20 63 6f 75 6c 64 20 6d 6f |ise you could mo| 00002950 64 69 66 79 20 74 68 65 20 65 72 72 6f 72 0d 72 |dify the error.r| 00002960 6f 75 74 69 6e 65 20 74 6f 20 72 65 73 74 6f 72 |outine to restor| 00002970 65 20 74 68 65 20 7a 65 72 6f 20 70 61 67 65 20 |e the zero page | 00002980 62 79 74 65 73 20 62 65 66 6f 72 65 20 70 72 69 |bytes before pri| 00002990 6e 74 69 6e 67 20 74 68 65 20 65 72 72 6f 72 0d |nting the error.| 000029a0 6d 65 73 73 61 67 65 2e 20 49 66 20 79 6f 75 20 |message. If you | 000029b0 64 6f 20 74 68 65 72 65 20 69 73 20 6e 6f 20 6e |do there is no n| 000029c0 65 65 64 20 74 6f 20 62 61 6c 61 6e 63 65 20 74 |eed to balance t| 000029d0 68 65 20 73 74 61 63 6b 20 61 73 20 77 65 6c 6c |he stack as well| 000029e0 0d 62 65 63 61 75 73 65 20 69 74 20 77 69 6c 6c |.because it will| 000029f0 20 62 65 20 72 65 73 65 74 20 62 79 20 42 41 53 | be reset by BAS| 00002a00 49 43 20 77 68 65 6e 20 63 6f 6e 74 72 6f 6c 20 |IC when control | 00002a10 70 61 73 73 65 73 20 74 6f 20 74 68 65 20 42 52 |passes to the BR| 00002a20 4b 0d 69 6e 73 74 72 75 63 74 69 6f 6e 20 61 74 |K.instruction at| 00002a30 20 26 31 30 30 2e 0d 0d 0d 0d 20 20 20 31 30 20 | &100..... 10 | 00002a40 52 45 4d 3a 20 50 45 45 4b 0d 20 20 20 32 30 20 |REM: PEEK. 20 | 00002a50 4d 4f 44 45 37 0d 20 20 20 33 30 20 48 49 4d 45 |MODE7. 30 HIME| 00002a60 4d 3d 26 33 43 30 30 0d 20 20 20 34 30 20 44 49 |M=&3C00. 40 DI| 00002a70 4d 20 73 61 76 65 20 35 30 0d 20 20 20 35 30 20 |M save 50. 50 | 00002a80 64 69 66 66 3d 26 38 30 30 30 2d 48 49 4d 45 4d |diff=&8000-HIMEM| 00002a90 0d 20 20 20 36 30 20 61 64 64 72 65 73 73 3d 26 |. 60 address=&| 00002aa0 37 30 0d 20 20 20 37 30 20 65 72 72 73 74 61 63 |70. 70 errstac| 00002ab0 6b 3d 26 31 30 30 0d 20 20 20 38 30 20 63 6f 6d |k=&100. 80 com| 00002ac0 76 65 63 3d 26 46 32 0d 20 20 20 39 30 20 67 73 |vec=&F2. 90 gs| 00002ad0 69 6e 69 74 3d 26 46 46 43 32 0d 20 20 31 30 30 |init=&FFC2. 100| 00002ae0 20 67 73 72 65 61 64 3d 26 46 46 43 35 0d 20 20 | gsread=&FFC5. | 00002af0 31 31 30 20 6f 73 61 73 63 69 3d 26 46 46 45 33 |110 osasci=&FFE3| 00002b00 0d 20 20 31 32 30 20 6f 73 6e 65 77 6c 3d 26 46 |. 120 osnewl=&F| 00002b10 46 45 37 0d 20 20 31 33 30 20 6f 73 63 6c 69 3d |FE7. 130 oscli=| 00002b20 26 46 46 46 37 0d 20 20 31 34 30 20 46 4f 52 20 |&FFF7. 140 FOR | 00002b30 70 61 73 73 20 3d 20 30 20 54 4f 20 32 20 53 54 |pass = 0 TO 2 ST| 00002b40 45 50 20 32 0d 20 20 31 35 30 20 50 25 3d 48 49 |EP 2. 150 P%=HI| 00002b50 4d 45 4d 0d 20 20 31 36 30 20 5b 20 20 20 20 20 |MEM. 160 [ | 00002b60 20 20 4f 50 54 20 70 61 73 73 0d 20 20 31 37 30 | OPT pass. 170| 00002b70 20 20 20 20 20 20 20 20 20 42 52 4b 0d 20 20 31 | BRK. 1| 00002b80 38 30 20 20 20 20 20 20 20 20 20 42 52 4b 0d 20 |80 BRK. | 00002b90 20 31 39 30 20 20 20 20 20 20 20 20 20 42 52 4b | 190 BRK| 00002ba0 0d 20 20 32 30 30 20 20 20 20 20 20 20 20 20 4a |. 200 J| 00002bb0 4d 50 20 73 65 72 76 69 63 65 2b 64 69 66 66 0d |MP service+diff.| 00002bc0 20 20 32 31 30 20 20 20 20 20 20 20 20 20 4f 50 | 210 OP| 00002bd0 54 20 46 4e 65 71 75 62 28 26 38 32 29 0d 20 20 |T FNequb(&82). | 00002be0 32 32 30 20 20 20 20 20 20 20 20 20 4f 50 54 20 |220 OPT | 00002bf0 46 4e 65 71 75 62 28 28 63 6f 70 79 72 69 67 68 |FNequb((copyrigh| 00002c00 74 2b 64 69 66 66 29 20 4d 4f 44 20 32 35 36 29 |t+diff) MOD 256)| 00002c10 0d 20 20 32 33 30 20 20 20 20 20 20 20 20 20 42 |. 230 B| 00002c20 52 4b 0d 20 20 32 34 30 20 2e 74 69 74 6c 65 0d |RK. 240 .title.| 00002c30 20 20 32 35 30 20 20 20 20 20 20 20 20 20 4f 50 | 250 OP| 00002c40 54 20 46 4e 65 71 75 73 28 22 50 45 45 4b 22 29 |T FNequs("PEEK")| 00002c50 0d 20 20 32 36 30 20 2e 63 6f 70 79 72 69 67 68 |. 260 .copyrigh| 00002c60 74 0d 20 20 32 37 30 20 20 20 20 20 20 20 20 20 |t. 270 | 00002c70 42 52 4b 0d 20 20 32 38 30 20 20 20 20 20 20 20 |BRK. 280 | 00002c80 20 20 4f 50 54 20 46 4e 65 71 75 73 28 22 28 43 | OPT FNequs("(C| 00002c90 29 20 47 6f 72 64 6f 6e 20 48 6f 72 73 69 6e 67 |) Gordon Horsing| 00002ca0 74 6f 6e 20 31 39 38 37 22 29 0d 20 20 32 39 30 |ton 1987"). 290| 00002cb0 20 20 20 20 20 20 20 20 20 42 52 4b 0d 20 20 33 | BRK. 3| 00002cc0 30 30 20 2e 73 65 72 76 69 63 65 0d 20 20 33 31 |00 .service. 31| 00002cd0 30 20 20 20 20 20 20 20 20 20 43 4d 50 20 23 34 |0 CMP #4| 00002ce0 0d 20 20 33 32 30 20 20 20 20 20 20 20 20 20 42 |. 320 B| 00002cf0 45 51 20 75 6e 72 65 63 6f 67 6e 69 73 65 64 0d |EQ unrecognised.| 00002d00 20 20 33 33 30 20 20 20 20 20 20 20 20 20 52 54 | 330 RT| 00002d10 53 0d 20 20 33 34 30 20 2e 75 6e 72 65 63 6f 67 |S. 340 .unrecog| 00002d20 6e 69 73 65 64 0d 20 20 33 35 30 20 20 20 20 20 |nised. 350 | 00002d30 20 20 20 20 50 48 41 0d 20 20 33 36 30 20 20 20 | PHA. 360 | 00002d40 20 20 20 20 20 20 54 58 41 0d 20 20 33 37 30 20 | TXA. 370 | 00002d50 20 20 20 20 20 20 20 20 50 48 41 0d 20 20 33 38 | PHA. 38| 00002d60 30 20 20 20 20 20 20 20 20 20 54 59 41 0d 20 20 |0 TYA. | 00002d70 33 39 30 20 20 20 20 20 20 20 20 20 50 48 41 0d |390 PHA.| 00002d80 20 20 34 30 30 20 20 20 20 20 20 20 20 20 4c 44 | 400 LD| 00002d90 58 20 23 26 46 46 0d 20 20 34 31 30 20 2e 63 6f |X #&FF. 410 .co| 00002da0 6d 6c 6f 6f 70 0d 20 20 34 32 30 20 20 20 20 20 |mloop. 420 | 00002db0 20 20 20 20 49 4e 58 0d 20 20 34 33 30 20 20 20 | INX. 430 | 00002dc0 20 20 20 20 20 20 4c 44 41 20 74 69 74 6c 65 2b | LDA title+| 00002dd0 64 69 66 66 2c 58 0d 20 20 34 34 30 20 20 20 20 |diff,X. 440 | 00002de0 20 20 20 20 20 42 45 51 20 66 6f 75 6e 64 0d 20 | BEQ found. | 00002df0 20 34 35 30 20 20 20 20 20 20 20 20 20 4c 44 41 | 450 LDA| 00002e00 20 28 63 6f 6d 76 65 63 29 2c 59 0d 20 20 34 36 | (comvec),Y. 46| 00002e10 30 20 20 20 20 20 20 20 20 20 49 4e 59 0d 20 20 |0 INY. | 00002e20 34 37 30 20 20 20 20 20 20 20 20 20 43 4d 50 20 |470 CMP | 00002e30 23 41 53 43 28 22 2e 22 29 0d 20 20 34 38 30 20 |#ASC("."). 480 | 00002e40 20 20 20 20 20 20 20 20 42 45 51 20 66 6f 75 6e | BEQ foun| 00002e50 64 0d 20 20 34 39 30 20 20 20 20 20 20 20 20 20 |d. 490 | 00002e60 41 4e 44 20 23 26 44 46 0d 20 20 35 30 30 20 20 |AND #&DF. 500 | 00002e70 20 20 20 20 20 20 20 43 4d 50 20 74 69 74 6c 65 | CMP title| 00002e80 2b 64 69 66 66 2c 58 0d 20 20 35 31 30 20 20 20 |+diff,X. 510 | 00002e90 20 20 20 20 20 20 42 45 51 20 63 6f 6d 6c 6f 6f | BEQ comloo| 00002ea0 70 0d 20 20 35 32 30 20 20 20 20 20 20 20 20 20 |p. 520 | 00002eb0 50 4c 41 0d 20 20 35 33 30 20 20 20 20 20 20 20 |PLA. 530 | 00002ec0 20 20 54 41 59 0d 20 20 35 34 30 20 20 20 20 20 | TAY. 540 | 00002ed0 20 20 20 20 50 4c 41 0d 20 20 35 35 30 20 20 20 | PLA. 550 | 00002ee0 20 20 20 20 20 20 54 41 58 0d 20 20 35 36 30 20 | TAX. 560 | 00002ef0 20 20 20 20 20 20 20 20 50 4c 41 0d 20 20 35 37 | PLA. 57| 00002f00 30 20 20 20 20 20 20 20 20 20 52 54 53 0d 20 20 |0 RTS. | 00002f10 35 38 30 20 2e 66 6f 75 6e 64 0d 20 20 35 39 30 |580 .found. 590| 00002f20 20 20 20 20 20 20 20 20 20 43 4c 43 0d 20 20 36 | CLC. 6| 00002f30 30 30 20 20 20 20 20 20 20 20 20 4a 53 52 20 67 |00 JSR g| 00002f40 73 69 6e 69 74 0d 20 20 36 31 30 20 20 20 20 20 |sinit. 610 | 00002f50 20 20 20 20 4c 44 41 20 61 64 64 72 65 73 73 0d | LDA address.| 00002f60 20 20 36 32 30 20 20 20 20 20 20 20 20 20 50 48 | 620 PH| 00002f70 41 0d 20 20 36 33 30 20 20 20 20 20 20 20 20 20 |A. 630 | 00002f80 4c 44 41 20 61 64 64 72 65 73 73 2b 31 0d 20 20 |LDA address+1. | 00002f90 36 34 30 20 20 20 20 20 20 20 20 20 50 48 41 0d |640 PHA.| 00002fa0 20 20 36 35 30 20 20 20 20 20 20 20 20 20 4c 44 | 650 LD| 00002fb0 58 20 23 30 0d 20 20 36 36 30 20 20 20 20 20 20 |X #0. 660 | 00002fc0 20 20 20 53 54 58 20 61 64 64 72 65 73 73 0d 20 | STX address. | 00002fd0 20 36 37 30 20 20 20 20 20 20 20 20 20 53 54 58 | 670 STX| 00002fe0 20 61 64 64 72 65 73 73 2b 31 0d 20 20 36 38 30 | address+1. 680| 00002ff0 20 20 20 20 20 20 20 20 20 44 45 58 0d 20 20 36 | DEX. 6| 00003000 39 30 20 2e 61 72 67 6c 6f 6f 70 0d 20 20 37 30 |90 .argloop. 70| 00003010 30 20 20 20 20 20 20 20 20 20 4a 53 52 20 67 73 |0 JSR gs| 00003020 72 65 61 64 0d 20 20 37 31 30 20 20 20 20 20 20 |read. 710 | 00003030 20 20 20 42 43 53 20 65 6e 64 61 72 67 0d 20 20 | BCS endarg. | 00003040 37 32 30 20 20 20 20 20 20 20 20 20 43 4d 50 20 |720 CMP | 00003050 23 41 53 43 28 22 26 22 29 0d 20 20 37 33 30 20 |#ASC("&"). 730 | 00003060 20 20 20 20 20 20 20 20 42 45 51 20 61 72 67 6c | BEQ argl| 00003070 6f 6f 70 0d 20 20 37 34 30 20 20 20 20 20 20 20 |oop. 740 | 00003080 20 20 4a 53 52 20 63 6f 6e 76 65 72 74 2b 64 69 | JSR convert+di| 00003090 66 66 0d 20 20 37 35 30 20 20 20 20 20 20 20 20 |ff. 750 | 000030a0 20 50 48 41 20 20 20 20 20 20 20 20 20 20 20 5c | PHA \| 000030b0 20 50 75 73 68 20 68 65 78 20 6e 79 62 62 6c 65 | Push hex nybble| 000030c0 73 0d 20 20 37 36 30 20 20 20 20 20 20 20 20 20 |s. 760 | 000030d0 49 4e 58 0d 20 20 37 37 30 20 20 20 20 20 20 20 |INX. 770 | 000030e0 20 20 42 50 4c 20 61 72 67 6c 6f 6f 70 0d 20 20 | BPL argloop. | 000030f0 37 38 30 20 2e 65 6e 64 61 72 67 0d 20 20 37 39 |780 .endarg. 79| 00003100 30 20 20 20 20 20 20 20 20 20 43 50 58 20 23 34 |0 CPX #4| 00003110 0d 20 20 38 30 30 20 20 20 20 20 20 20 20 20 42 |. 800 B| 00003120 43 53 20 65 72 72 6f 72 0d 20 20 38 31 30 20 20 |CS error. 810 | 00003130 20 20 20 20 20 20 20 50 4c 41 20 20 20 20 20 20 | PLA | 00003140 20 20 20 20 20 5c 20 4c 53 20 6e 79 62 62 6c 65 | \ LS nybble| 00003150 20 6c 6f 77 20 62 79 74 65 0d 20 20 38 32 30 20 | low byte. 820 | 00003160 20 20 20 20 20 20 20 20 53 54 41 20 61 64 64 72 | STA addr| 00003170 65 73 73 0d 20 20 38 33 30 20 20 20 20 20 20 20 |ess. 830 | 00003180 20 20 44 45 58 0d 20 20 38 34 30 20 20 20 20 20 | DEX. 840 | 00003190 20 20 20 20 42 4d 49 20 66 69 6e 69 73 68 0d 20 | BMI finish. | 000031a0 20 38 35 30 20 20 20 20 20 20 20 20 20 50 4c 41 | 850 PLA| 000031b0 20 20 20 20 20 20 20 20 20 20 20 5c 20 4d 53 20 | \ MS | 000031c0 6e 79 62 62 6c 65 20 6c 6f 77 20 62 79 74 65 0d |nybble low byte.| 000031d0 20 20 38 36 30 20 20 20 20 20 20 20 20 20 41 53 | 860 AS| 000031e0 4c 20 41 0d 20 20 38 37 30 20 20 20 20 20 20 20 |L A. 870 | 000031f0 20 20 41 53 4c 20 41 0d 20 20 38 38 30 20 20 20 | ASL A. 880 | 00003200 20 20 20 20 20 20 41 53 4c 20 41 0d 20 20 38 39 | ASL A. 89| 00003210 30 20 20 20 20 20 20 20 20 20 41 53 4c 20 41 0d |0 ASL A.| 00003220 20 20 39 30 30 20 20 20 20 20 20 20 20 20 4f 52 | 900 OR| 00003230 41 20 61 64 64 72 65 73 73 0d 20 20 39 31 30 20 |A address. 910 | 00003240 20 20 20 20 20 20 20 20 53 54 41 20 61 64 64 72 | STA addr| 00003250 65 73 73 20 20 20 5c 20 4c 53 20 62 79 74 65 0d |ess \ LS byte.| 00003260 20 20 39 32 30 20 20 20 20 20 20 20 20 20 44 45 | 920 DE| 00003270 58 0d 20 20 39 33 30 20 20 20 20 20 20 20 20 20 |X. 930 | 00003280 42 4d 49 20 66 69 6e 69 73 68 0d 20 20 39 34 30 |BMI finish. 940| 00003290 20 20 20 20 20 20 20 20 20 50 4c 41 20 20 20 20 | PLA | 000032a0 20 20 20 20 20 20 20 5c 20 4c 53 20 6e 79 62 62 | \ LS nybb| 000032b0 6c 65 20 68 69 67 68 20 62 79 74 65 0d 20 20 39 |le high byte. 9| 000032c0 35 30 20 20 20 20 20 20 20 20 20 53 54 41 20 61 |50 STA a| 000032d0 64 64 72 65 73 73 2b 31 0d 20 20 39 36 30 20 20 |ddress+1. 960 | 000032e0 20 20 20 20 20 20 20 44 45 58 0d 20 20 39 37 30 | DEX. 970| 000032f0 20 20 20 20 20 20 20 20 20 42 4d 49 20 66 69 6e | BMI fin| 00003300 69 73 68 0d 20 20 39 38 30 20 20 20 20 20 20 20 |ish. 980 | 00003310 20 20 50 4c 41 20 20 20 20 20 20 20 20 20 20 20 | PLA | 00003320 5c 20 4d 53 20 6e 79 62 62 6c 65 20 68 69 67 68 |\ MS nybble high| 00003330 20 62 79 74 65 0d 20 20 39 39 30 20 20 20 20 20 | byte. 990 | 00003340 20 20 20 20 41 53 4c 20 41 0d 20 31 30 30 30 20 | ASL A. 1000 | 00003350 20 20 20 20 20 20 20 20 41 53 4c 20 41 0d 20 31 | ASL A. 1| 00003360 30 31 30 20 20 20 20 20 20 20 20 20 41 53 4c 20 |010 ASL | 00003370 41 0d 20 31 30 32 30 20 20 20 20 20 20 20 20 20 |A. 1020 | 00003380 41 53 4c 20 41 0d 20 31 30 33 30 20 20 20 20 20 |ASL A. 1030 | 00003390 20 20 20 20 4f 52 41 20 61 64 64 72 65 73 73 2b | ORA address+| 000033a0 31 0d 20 31 30 34 30 20 20 20 20 20 20 20 20 20 |1. 1040 | 000033b0 53 54 41 20 61 64 64 72 65 73 73 2b 31 20 5c 20 |STA address+1 \ | 000033c0 4d 53 20 62 79 74 65 0d 20 31 30 35 30 20 2e 66 |MS byte. 1050 .f| 000033d0 69 6e 69 73 68 0d 20 31 30 36 30 20 20 20 20 20 |inish. 1060 | 000033e0 20 20 20 20 4c 44 59 20 23 30 0d 20 31 30 37 30 | LDY #0. 1070| 000033f0 20 20 20 20 20 20 20 20 20 4c 44 41 20 28 61 64 | LDA (ad| 00003400 64 72 65 73 73 29 2c 59 0d 20 31 30 38 30 20 20 |dress),Y. 1080 | 00003410 20 20 20 20 20 20 20 4a 53 52 20 68 65 78 62 79 | JSR hexby| 00003420 74 65 2b 64 69 66 66 0d 20 31 30 39 30 20 20 20 |te+diff. 1090 | 00003430 20 20 20 20 20 20 4a 53 52 20 6f 73 6e 65 77 6c | JSR osnewl| 00003440 0d 20 31 31 30 30 20 20 20 20 20 20 20 20 20 50 |. 1100 P| 00003450 4c 41 0d 20 31 31 31 30 20 20 20 20 20 20 20 20 |LA. 1110 | 00003460 20 53 54 41 20 61 64 64 72 65 73 73 2b 31 0d 20 | STA address+1. | 00003470 31 31 32 30 20 20 20 20 20 20 20 20 20 50 4c 41 |1120 PLA| 00003480 0d 20 31 31 33 30 20 20 20 20 20 20 20 20 20 53 |. 1130 S| 00003490 54 41 20 61 64 64 72 65 73 73 0d 20 31 31 34 30 |TA address. 1140| 000034a0 20 20 20 20 20 20 20 20 20 50 4c 41 0d 20 31 31 | PLA. 11| 000034b0 35 30 20 20 20 20 20 20 20 20 20 50 4c 41 0d 20 |50 PLA. | 000034c0 31 31 36 30 20 20 20 20 20 20 20 20 20 50 4c 41 |1160 PLA| 000034d0 0d 20 31 31 37 30 20 20 20 20 20 20 20 20 20 4c |. 1170 L| 000034e0 44 41 20 23 30 0d 20 31 31 38 30 20 20 20 20 20 |DA #0. 1180 | 000034f0 20 20 20 20 52 54 53 0d 20 31 31 39 30 20 2e 68 | RTS. 1190 .h| 00003500 65 78 62 79 74 65 0d 20 31 32 30 30 20 20 20 20 |exbyte. 1200 | 00003510 20 20 20 20 20 50 48 41 0d 20 31 32 31 30 20 20 | PHA. 1210 | 00003520 20 20 20 20 20 20 20 4c 53 52 20 41 0d 20 31 32 | LSR A. 12| 00003530 32 30 20 20 20 20 20 20 20 20 20 4c 53 52 20 41 |20 LSR A| 00003540 0d 20 31 32 33 30 20 20 20 20 20 20 20 20 20 4c |. 1230 L| 00003550 53 52 20 41 0d 20 31 32 34 30 20 20 20 20 20 20 |SR A. 1240 | 00003560 20 20 20 4c 53 52 20 41 0d 20 31 32 35 30 20 20 | LSR A. 1250 | 00003570 20 20 20 20 20 20 20 4a 53 52 20 6e 79 62 62 6c | JSR nybbl| 00003580 65 2b 64 69 66 66 0d 20 31 32 36 30 20 20 20 20 |e+diff. 1260 | 00003590 20 20 20 20 20 50 4c 41 0d 20 31 32 37 30 20 2e | PLA. 1270 .| 000035a0 6e 79 62 62 6c 65 0d 20 31 32 38 30 20 20 20 20 |nybble. 1280 | 000035b0 20 20 20 20 20 41 4e 44 20 23 26 46 0d 20 31 32 | AND #&F. 12| 000035c0 39 30 20 20 20 20 20 20 20 20 20 53 45 44 0d 20 |90 SED. | 000035d0 31 33 30 30 20 20 20 20 20 20 20 20 20 43 4c 43 |1300 CLC| 000035e0 0d 20 31 33 31 30 20 20 20 20 20 20 20 20 20 41 |. 1310 A| 000035f0 44 43 20 23 26 39 30 0d 20 31 33 32 30 20 20 20 |DC #&90. 1320 | 00003600 20 20 20 20 20 20 41 44 43 20 23 26 34 30 0d 20 | ADC #&40. | 00003610 31 33 33 30 20 20 20 20 20 20 20 20 20 43 4c 44 |1330 CLD| 00003620 0d 20 31 33 34 30 20 20 20 20 20 20 20 20 20 4a |. 1340 J| 00003630 4d 50 20 6f 73 61 73 63 69 0d 20 31 33 35 30 20 |MP osasci. 1350 | 00003640 2e 63 6f 6e 76 65 72 74 0d 20 31 33 36 30 20 20 |.convert. 1360 | 00003650 20 20 20 20 20 20 20 43 4d 50 20 23 41 53 43 28 | CMP #ASC(| 00003660 22 39 22 29 2b 31 0d 20 31 33 37 30 20 20 20 20 |"9")+1. 1370 | 00003670 20 20 20 20 20 42 43 53 20 6c 65 74 74 65 72 73 | BCS letters| 00003680 0d 20 31 33 38 30 20 20 20 20 20 20 20 20 20 43 |. 1380 C| 00003690 4d 50 20 23 41 53 43 28 22 30 22 29 0d 20 31 33 |MP #ASC("0"). 13| 000036a0 39 30 20 20 20 20 20 20 20 20 20 42 4d 49 20 65 |90 BMI e| 000036b0 72 72 6f 72 0d 20 31 34 30 30 20 20 20 20 20 20 |rror. 1400 | 000036c0 20 20 20 41 4e 44 20 23 26 46 0d 20 31 34 31 30 | AND #&F. 1410| 000036d0 20 20 20 20 20 20 20 20 20 52 54 53 0d 20 31 34 | RTS. 14| 000036e0 32 30 20 2e 6c 65 74 74 65 72 73 0d 20 31 34 33 |20 .letters. 143| 000036f0 30 20 20 20 20 20 20 20 20 20 53 42 43 20 23 26 |0 SBC #&| 00003700 33 37 0d 20 31 34 34 30 20 20 20 20 20 20 20 20 |37. 1440 | 00003710 20 43 4d 50 20 23 26 41 0d 20 31 34 35 30 20 20 | CMP #&A. 1450 | 00003720 20 20 20 20 20 20 20 42 4d 49 20 65 72 72 6f 72 | BMI error| 00003730 0d 20 31 34 36 30 20 20 20 20 20 20 20 20 20 43 |. 1460 C| 00003740 4d 50 20 23 26 31 30 0d 20 31 34 37 30 20 20 20 |MP #&10. 1470 | 00003750 20 20 20 20 20 20 42 43 53 20 65 72 72 6f 72 0d | BCS error.| 00003760 20 31 34 38 30 20 20 20 20 20 20 20 20 20 52 54 | 1480 RT| 00003770 53 0d 20 31 34 39 30 20 2e 65 72 72 6f 72 0d 20 |S. 1490 .error. | 00003780 31 35 30 30 20 20 20 20 20 20 20 20 20 4c 44 41 |1500 LDA| 00003790 20 23 28 65 72 72 6f 72 6d 73 67 2b 64 69 66 66 | #(errormsg+diff| 000037a0 29 20 4d 4f 44 20 32 35 36 0d 20 31 35 31 30 20 |) MOD 256. 1510 | 000037b0 20 20 20 20 20 20 20 20 53 54 41 20 61 64 64 72 | STA addr| 000037c0 65 73 73 0d 20 31 35 32 30 20 20 20 20 20 20 20 |ess. 1520 | 000037d0 20 20 4c 44 41 20 23 28 65 72 72 6f 72 6d 73 67 | LDA #(errormsg| 000037e0 2b 64 69 66 66 29 20 44 49 56 20 32 35 36 0d 20 |+diff) DIV 256. | 000037f0 31 35 33 30 20 20 20 20 20 20 20 20 20 53 54 41 |1530 STA| 00003800 20 61 64 64 72 65 73 73 2b 31 0d 20 31 35 34 30 | address+1. 1540| 00003810 20 20 20 20 20 20 20 20 20 4c 44 59 20 23 26 46 | LDY #&F| 00003820 46 0d 20 31 35 35 30 20 2e 65 72 72 6f 72 6c 6f |F. 1550 .errorlo| 00003830 6f 70 0d 20 31 35 36 30 20 20 20 20 20 20 20 20 |op. 1560 | 00003840 20 49 4e 59 0d 20 31 35 37 30 20 20 20 20 20 20 | INY. 1570 | 00003850 20 20 20 4c 44 41 20 28 61 64 64 72 65 73 73 29 | LDA (address)| 00003860 2c 59 0d 20 31 35 38 30 20 20 20 20 20 20 20 20 |,Y. 1580 | 00003870 20 53 54 41 20 65 72 72 73 74 61 63 6b 2c 59 0d | STA errstack,Y.| 00003880 20 31 35 39 30 20 20 20 20 20 20 20 20 20 42 50 | 1590 BP| 00003890 4c 20 65 72 72 6f 72 6c 6f 6f 70 0d 20 31 36 30 |L errorloop. 160| 000038a0 30 20 20 20 20 20 20 20 20 20 4a 4d 50 20 65 72 |0 JMP er| 000038b0 72 73 74 61 63 6b 0d 20 31 36 31 30 20 2e 65 72 |rstack. 1610 .er| 000038c0 72 6f 72 6d 73 67 0d 20 31 36 32 30 20 20 20 20 |rormsg. 1620 | 000038d0 20 20 20 20 20 42 52 4b 0d 20 31 36 33 30 20 20 | BRK. 1630 | 000038e0 20 20 20 20 20 20 20 42 52 4b 0d 20 31 36 34 30 | BRK. 1640| 000038f0 20 20 20 20 20 20 20 20 20 4f 50 54 20 46 4e 65 | OPT FNe| 00003900 71 75 73 28 22 4f 75 74 20 6f 66 20 72 61 6e 67 |qus("Out of rang| 00003910 65 22 29 0d 20 31 36 35 30 20 20 20 20 20 20 20 |e"). 1650 | 00003920 20 20 42 52 4b 0d 20 31 36 36 30 20 20 20 20 20 | BRK. 1660 | 00003930 20 20 20 20 4f 50 54 20 46 4e 65 71 75 62 28 26 | OPT FNequb(&| 00003940 46 46 29 0d 20 31 36 37 30 20 2e 6c 61 73 74 62 |FF). 1670 .lastb| 00003950 79 74 65 0d 20 31 36 38 30 20 5d 0d 20 31 36 39 |yte. 1680 ]. 169| 00003960 30 20 4e 45 58 54 0d 20 31 37 30 30 20 49 4e 50 |0 NEXT. 1700 INP| 00003970 55 54 27 22 53 61 76 65 20 66 69 6c 65 6e 61 6d |UT'"Save filenam| 00003980 65 20 3d 20 22 66 69 6c 65 6e 61 6d 65 24 0d 20 |e = "filename$. | 00003990 31 37 31 30 20 49 46 20 66 69 6c 65 6e 61 6d 65 |1710 IF filename| 000039a0 24 3d 22 22 20 45 4e 44 0d 20 31 37 32 30 20 24 |$="" END. 1720 $| 000039b0 73 61 76 65 3d 22 53 41 56 45 20 22 2b 66 69 6c |save="SAVE "+fil| 000039c0 65 6e 61 6d 65 24 2b 22 20 22 2b 53 54 52 24 7e |ename$+" "+STR$~| 000039d0 28 48 49 4d 45 4d 29 2b 22 20 22 2b 53 54 52 24 |(HIMEM)+" "+STR$| 000039e0 7e 28 6c 61 73 0d 20 20 20 20 20 20 74 62 79 74 |~(las. tbyt| 000039f0 65 29 2b 22 20 46 46 46 46 38 30 30 30 20 46 46 |e)+" FFFF8000 FF| 00003a00 46 46 38 30 30 30 22 0d 20 31 37 33 30 20 58 25 |FF8000". 1730 X%| 00003a10 3d 73 61 76 65 20 4d 4f 44 20 32 35 36 0d 20 31 |=save MOD 256. 1| 00003a20 37 34 30 20 59 25 3d 73 61 76 65 20 44 49 56 20 |740 Y%=save DIV | 00003a30 32 35 36 0d 20 31 37 35 30 20 2a 4f 50 54 31 2c |256. 1750 *OPT1,| 00003a40 32 0d 20 31 37 36 30 20 43 41 4c 4c 20 6f 73 63 |2. 1760 CALL osc| 00003a50 6c 69 0d 20 31 37 37 30 20 2a 4f 50 54 31 2c 30 |li. 1770 *OPT1,0| 00003a60 0d 20 31 37 38 30 20 45 4e 44 0d 20 31 37 39 30 |. 1780 END. 1790| 00003a70 20 44 45 46 46 4e 65 71 75 62 28 62 79 74 65 29 | DEFFNequb(byte)| 00003a80 0d 20 31 38 30 30 20 3f 50 25 3d 62 79 74 65 0d |. 1800 ?P%=byte.| 00003a90 20 31 38 31 30 20 50 25 3d 50 25 2b 31 0d 20 31 | 1810 P%=P%+1. 1| 00003aa0 38 32 30 20 3d 70 61 73 73 0d 20 31 38 33 30 20 |820 =pass. 1830 | 00003ab0 44 45 46 46 4e 65 71 75 77 28 77 6f 72 64 29 0d |DEFFNequw(word).| 00003ac0 20 31 38 34 30 20 3f 50 25 3d 77 6f 72 64 20 4d | 1840 ?P%=word M| 00003ad0 4f 44 20 32 35 36 0d 20 31 38 35 30 20 50 25 3f |OD 256. 1850 P%?| 00003ae0 31 3d 77 6f 72 64 20 44 49 56 20 32 35 36 0d 20 |1=word DIV 256. | 00003af0 31 38 36 30 20 50 25 3d 50 25 2b 32 0d 20 31 38 |1860 P%=P%+2. 18| 00003b00 37 30 20 3d 70 61 73 73 0d 20 31 38 38 30 20 44 |70 =pass. 1880 D| 00003b10 45 46 46 4e 65 71 75 64 28 64 6f 75 62 6c 65 29 |EFFNequd(double)| 00003b20 0d 20 31 38 39 30 20 21 50 25 3d 64 6f 75 62 6c |. 1890 !P%=doubl| 00003b30 65 0d 20 31 39 30 30 20 50 25 3d 50 25 2b 34 0d |e. 1900 P%=P%+4.| 00003b40 20 31 39 31 30 20 3d 70 61 73 73 0d 20 31 39 32 | 1910 =pass. 192| 00003b50 30 20 44 45 46 46 4e 65 71 75 73 28 73 74 72 69 |0 DEFFNequs(stri| 00003b60 6e 67 24 29 0d 20 31 39 33 30 20 24 50 25 3d 73 |ng$). 1930 $P%=s| 00003b70 74 72 69 6e 67 24 0d 20 31 39 34 30 20 50 25 3d |tring$. 1940 P%=| 00003b80 50 25 2b 4c 45 4e 28 73 74 72 69 6e 67 24 29 0d |P%+LEN(string$).| 00003b90 20 31 39 35 30 20 3d 70 61 73 73 0d | 1950 =pass.| 00003b9c