Atari 8-bit Source code

100 DIM VAR$(3),PM$(256),C$(11):POKE 106,PEEK(106)-8:GRAPHICS 0:LOC=PEEK(106)*256+1024:LEN=256:POKE 752, 1
110 PRINT:VAR$="PM$":POKE 704,30:GOSUB 290:PM$=CHR$(0):PM$(256)=CHR$(0):PM$(2)=PM$(1):C$=PM$
120 FOR X=3 TO 9:READ AZ:C$(X,X)=CHR$(AZ):NEXT X:POKE 559,62:POKE 53277,3:POKE 54279,PEEK(106):PMV=40:PMH=60
130 ST=STICK(0):IF ST=15 THEN 130
140 IF ST=5 THEN PMH=PMH+1:PMV=PMV+2
150 IF ST=6 THEN PMH=PMH+1:PMV=PMV-2
160 IF ST=7 THEN PMH=PMH+1
170 IF ST=9 THEN PMH=PMH-1:PMV=PMV+2
180 IF ST=10 THEN PMH=PMH-1:PMV=PMV-2
190 IF ST=11 THEN PMH=PMH-1
200 IF ST=13 THEN PMV=PMV+2
210 IF ST=14 THEN PMV=PMV-2
220 IF PMV<1 THEN PMV=256
230 IF PMV>256 THEN PMV=1
240 IF PMH<30 THEN PMH=220
250 IF PMH>220 THEN PMH=30
260 POKE 53248,PMH:PM$(PMV)=C$
270 GOTO 130
280 DATA 68,170,136,68,34,170,68
290 VNTP=PEEK(130)+PEEK(131)*256
300 VNTD=PEEK(132)+PEEK(133)*256
310 VVTP=PEEK(134)+PEEK(135)*256
320 STARP=PEEK(140)+PEEK(141)*256
330 AZ1=-1
340 AZ1=AZ1+1:FOR AZ=1 TO LEN(VAR$)
350 AZ2=PEEK(VNTP):IF AZ2>127 AND AZ<LEN(VAR$) THEN 370
360 IF AZ2-128*(AZ2>127)=ASC(VAR$(AZ)) THEN VNTP=VNTP+1:NEXT AZ:GOTO 400
370 IF PEEK(VNTP)<128 THEN VNTP=VNTP+1:GOTO 370
380 VNTP=VNTP+1:IF VNTP<VNTD THEN 340
390 GRAPHICS 0:? VAR$;" ISN'T A LEGAL VARIABLE":END
400 AZ=VVTP+AZ1*8+2:IF PEEK(AZ-2)<> 129 THEN 380
410 AZ1=LOC-STARP:GOSUB 430:AZ1=LEN:GOSUB 430:AZ1=LEN:GOSUB 430
420 RETURN
430 AZ2=INT(AZ1/256):AZ1=AZ1-AZ2*256:POKE AZ,AZ1:POKE AZ+1,AZ2:AZ=AZ+2:RETURN