On 28 Dec 2019 at 18:11, tom ehlert wrote:
> >When I couldn't get a reading on my scope I decided a more direct approach
> >by piping direct from
> the console:
> >ECHO TEST>COM1
>
> good idea. unfortunately this only works with proper DTR/CTS/RTS/... status
> lines
> connected.
>
>
> Tom
Ma
Dear Matt,
first and foremost, thumbs up for approaching the problem with an
oscilloscope. This is the right tool for the job.
Mr. Bret Johnson (himself a programming wizard/veteran) has already
provided a super-gentle debugging intro...
If I remember correctly, the DOS and BIOS services that
> MODE COM1:BAUD=9600 DATA=8 STOP=1 PARITY=N DTR=OFF RTS=OFF
MODE (for anyDOS) does nothing sensible about DTR/RTS.
(it might set the status line outputs, I don't know.
there is no way to change the input of status line behaviour.
> I suspect that DTR/RTS being on is the reason why I cannot wri
The first thing you should do is to make sure COM1 is even set up correctly on
your computer. On older computers the COM ports were automatically enabled,
but on newer computers they aren't always turned on. I think the easiest way
to check is to get into DEBUG (from the DOS prompt and enter:
