mirror of
https://github.com/nathanriggs/AppleIIAsm-Collection.git
synced 2025-02-18 15:30:36 +00:00
45 lines
1.5 KiB
NASM
45 lines
1.5 KiB
NASM
*
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*``````````````````````````````*
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* TXTCLR (NATHAN RIGGS) *
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* *
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* INPUT: *
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* *
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* .A = FILL CHARACTER *
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* *
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* OUTPUT: *
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* *
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* FILLS THE SCREEN WITH THE *
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* GIVEN CHARACTER. FILLS BY *
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* SECTION TO AVOID CHANGING *
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* SCREENHOLE VALUES. *
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* *
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* DESTROYS: NZCIDV *
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* ^^ *
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* *
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* CYCLES: 42+ *
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* SIZE: 37 BYTES *
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*,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
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*
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]F EQU ZPB1 ; FILL CHARACTER
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*
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TXTCLR
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*
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STA ]F ; {4C3B} STORE FILL CHAR IN MEM
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LDY #$78 ; {2C2B} LENGTH OF EACH SCREEN SECTION
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:LP1
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STA $400,Y ; {5C3B} 1ST SECTION
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STA $480,Y ; {5C3B} 2ND SECTION
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STA $500,Y ; {5C3B} 3RD SECTION
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STA $580,Y ; {5C3B} 4TH SECTION
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CPY #120 ; {2C2B} -- #80
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BPL :NDB ; {3C2B}
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STA $600,Y ; {5C3B} 5TH SECTION
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STA $680,Y ; {5C3B} 6TH SECTION
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STA $700,Y ; {5C3B} 7TH SECTION
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STA $780,Y ; {5C3B} 8TH SECTION
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:NDB
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DEY ; {2C1B} DECREASE BYTE COUNTER
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BPL :LP1 ; {3C2B} IF POSITIVE, KEEP LOOPING
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RTS ; {6C1B} RETURN TO CALLING ROUTINE
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*
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