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30 lines
1.0 KiB
NASM
30 lines
1.0 KiB
NASM
;title LPTPORT.ASM - Switch Printer Ports Between LPT1: and LPT2:
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;
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; (C) Copyright 1984, Dickinson Associates Inc.
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;
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ROM_BIOS_DATA segment at 40h ; Low Memory "BIOS" Parameters at 40H
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org 8h ; Printer port addresses are at byte 8
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PRINTER_BASE dw 4 dup(?) ; Four words for Printer Port
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; I/O Address Locations
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ROM_BIOS_DATA ends ; End of data segment
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;
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CODE_SEG segment para 'code'
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;
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assume ds:ROM_BIOS_DATA, cs:CODE_SEG, ss:NOTHING, es:NOTHING
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org 100h ; .COM format program
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;
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BEGIN:
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mov ax,ROM_BIOS_DATA ; Make ROM_BIOS_DATA addressable
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mov ds,ax ; via DS register.
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;
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mov ax,PRINTER_BASE[0] ; Move LPT1: port address to AX
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mov bx,PRINTER_BASE[2] ; Move LPT2: port address to BX
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mov PRINTER_BASE[0],bx ; Switch the port addresses around
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mov PRINTER_BASE[2],ax ; by moving them back in reverse order.
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;
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ret ; Back to PC-DOS
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;
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CODE_SEG ends ; End of code segment
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;
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end BEGIN ; End of program
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