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33 lines
783 B
ArmAsm
33 lines
783 B
ArmAsm
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; Tiny Text
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; by Vince `deater` Weaver, vince@deater.net --- d e s i r e ---
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; scrolling hexadecimal numbers
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; hard to do much in 8-bytes on Apple II
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; zero page locations
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; ROM calls
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SETGR = $FB40 ; set lo-res graphics code, clear screen
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PRHEX = $FDE3 ; print hex digit
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COUT = $FDED ; output A to screen
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COUT1 = $FDF0 ; output A to screen
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; load to zero page
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.zeropage
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tiny_text:
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tiny_loop:
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lda $00,X ; get value from zero page
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jsr PRHEX ; convert to hex digit and print, with scroll
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; jsr COUT
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inx ; move to next location
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bvc tiny_loop ; branch always (depends on the V flag
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; being clear, which it should be?)
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; we could maybe use a proper branch code
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; if we can prove the output of COUT has
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; any guarantees
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