54 lines
1.5 KiB
ArmAsm
54 lines
1.5 KiB
ArmAsm
__MAIN = $1000
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.include "dos33.inc"
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.include "ca65.inc"
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KEYBOARD = $C000
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KEYSTROBE = $C010
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TXTCLR = $C050 ; Mode Graphics
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MIXCLR = $C052 ; Full screen
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MIXSET = $C053 ; Split screen
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PAGE1 = $C054
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HIRES = $C057 ; Mode HGR
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HgrLo = $F5
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HgrHi = $F6
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glyph = $FE
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DrawChar = $310
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DemoCharInspect:
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BIT PAGE1 ; Page 1
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BIT TXTCLR ; not text, but graphics
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BIT MIXSET ; Split screen text/graphics
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BIT HIRES ; HGR, no GR
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LDA #0 ; glyph=0
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STA glyph ; save which glyph to draw
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.a LDA #0 ; screen = 0x2000
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STA HgrLo ;
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LDA #$20 ; HGR Page 1
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STA HgrHi ;
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LDA glyph ; A = glyph
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LDY #00 ; Y = col
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JSR DrawChar
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.b LDA KEYBOARD ; read A=key
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BPL .b ; no key?
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STA KEYSTROBE ; debounce key
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CMP #$88 ; key == <-- ? CTRL-H
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BNE .d ;
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DEC glyph ; yes, --glyph
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.c LDA glyph ; glyph &= 0x7F
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AND #$7F ;
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STA glyph ;
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BPL .a ; always branch, draw prev char
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.d CMP #$95 ; key == --> ? CTRL-U
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BNE .e ;
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INC glyph ; yes, ++glyph
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CLC ; always branch
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BCC .c ; draw prev char
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.e CMP #$9B ; key == ESC ?
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BNE .b ;
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RTS ; yes, exit
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__END:
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