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RS232OFF.ASM
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Assembly Source File
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1989-02-11
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823b
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41 lines
;RS232OFF.ASM - Turn off RS232 on all 4 COM ports
;By Keith Petersen, W8SDZ - February 11, 1989
;Assemble with A86 shareware assembler
cli ;we don't want to be interrupted while we do this
mov al,0 ;get a zero for resetting everything
;First turn off the UART interrupts on all four ports
mov dx,03f9h ;com1
out dx,al
mov dx,02f9h ;com2
out dx,al
mov dx,03e9h ;com3
out dx,al
mov dx,02e9h ;com4
out dx,al
;Now turn off DTR and RTS on all four ports
mov dx,03fch ;com1
out dx,al
mov dx,02fch ;com2
out dx,al
mov dx,03ech ;com3
out dx,al
mov dx,02ech ;com4
out dx,al
;We're done
int 20h ;standard end program interrupt