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- title Processor to turn off COM DTR
- ;
- ; This program turns off the DTR signal on the communications
- ; port of a Zenith Z100 micro. This makes the Z100 compatible
- ; with the Gandalf PACX communications switch. The execution
- ; of this program should be the FIRST thing in the AUTOEXEC.BAT
- ; file. It MUST be before the DATE & TIME calls.
- ;
- ; This program is necesary because the vanila ZDOS leaves
- ; the DTR signal on after a reset or boot. A preferable
- ; solution would be to fix ZDOS, but this works too. Note that
- ; in either case it is the user's terminal emulator's resposibility
- ; to insure that DTR is raised at the beginning of a session AND
- ; lowered at the end.
- ;
- ; Mitch Blank
- ;
- name OFF
- code segment byte public 'code'
- assume cs:code,ds:code,es:code,ss:code
- org 100h
- start: mov al,4 ; Turn off DTR & RTS
- out 0EFh,al
- int 20h
- code ends
- end start
-
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