45 lines
577 B
ArmAsm
45 lines
577 B
ArmAsm
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.define putchar,getchar
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! output routine in monitor for the nascom
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CRT = 0x013B
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! output a charcter
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! entry: ascii character in a
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.text
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putchar:
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push hl
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push bc
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ld hl,tab
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ld b,5
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1: cp (hl)
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jr z,fetch
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inc hl
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inc hl
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djnz 1b
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2: call CRT
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pop bc
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pop hl
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ret
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fetch: inc hl
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ld a,(hl)
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jr 2b
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! conversion table for nascom characters
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tab: .byte 0x0D,0x00
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.byte 0x1B,0x1E
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.byte 0x08,0x1D
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.byte 0x0A,0x1F
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.byte 0x7F,0x00
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KBD = 0x69
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get character from keyboard
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getchar:
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call KBD
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jr nc,getchar
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cp 0x1F
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jr z,CR
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cp 0x1D
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jr z,BS
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ret
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CR: ld a,0xA
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ret
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BS: ld a,0x8
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ret
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