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img0042.txt
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img0042.txt
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FILE: EOSABS:EOS TF HEWLETT-PACKARD: A_uOS O00 (c) Coleco 1983Conf identia}! Sat, 8 Sep 1984, 23.38 PAGE 38
LOCATION OBJECT CODE LINE SOURCE LINE
1442 ;
1443 ; Name: FILLVRAM
1444 ;
1445 ; Function: Fill a VRAM memory buffer with a constant byte value.
1446 ;
1447 ; Entry: A - constant byte vaiue to be written
1446 ; DE - number of bytes itnthe VRAM memory buffer
1449 ; HL - starting VRAM address to be written to
1450 ;
1451 ; Exit: None.
1452 ;
1453 ; Registers used: AF, C, DE
1454 ;
1455 Size: ROM - 18 bytes
1456 RAM - O bytes
1457 -
1458 Comments: This version of FILL_VRAM is provided for stand alone operation.
1459 This routine does a direct access to the COLECOVISION I/O ports.
1460
1461 Comparision: edited for documentation
1462 uneeded call to READREGISTER taken out
1463
1464
E053 1465 FILL VRAM:
EO59 F5 1466 PUSH AF -Save the data to fill with
EOSA CDEIES 1467 CALL SET_WRITE ;Sets the ctrl port data and
EOSD E1 1468 POP HL ;popping AF into HL to restore the fill data
EOSE 1469 FILL: . ;repeat
1470 ; get back a copy of the saved constant
EOSE ED61 1471 ouT {[C],.H ; write the constant out to the VRAM buffer
EO6O 18 1472 DEC DE ; byte count = byte count - 1
EOG1 7A 1473 LD A,O suntil byte count = O
E062 B83 1474 OR E
EO63 20F9 1475 JR NZ,FILL
EO65S C9 1476 RET ;all done