[Coco] Re: Coco printer primer...

Gene Heskett gene.heskett at verizon.net
Wed Feb 15 23:31:49 EST 2006

On Wednesday 15 February 2006 17:58, Torsten Dittel wrote:
>> I have access to an Okidata 320T (OS compatible down to MS DOS, and
>> emulates IBM ProPrinter III, Epson Fx-80, ANSI and Oki Microline)
>> with a RS-232C serial adapter that works great. Would making a
>> serial cable to work with the 'bit banger' port (do not have a
>> RS-232c cart yet) be difficult? I know on a PC this wouldn't be a
>> problem, but, using the four pins from the b/b port to a 25 pin
>> sounds too easy of a solution...
>Well, the signal levels of RS-232 (logical "one" is between -12V and
>-3V, "zero" between +3V and +12V) are different from what's on the
>bitbanger port (0V or 5V). Normally you'd need a small circuit with
> it's own power supply which contains a MAX232 compatible IC which
> will adapt the CoCo's levels to the standard. However, some printers
> might accept the CoCo's signals and I'm sure there's a workaround
> without too much hardware efforts. Another question is if you have
> real CTS/RTS hardware handshake or XON/XOFF protocol software
> handshake.

I think your bit-banger is busted if its only doing 0-5 volts.  The one 
time I checked one of mine it was doing + and - around 7.5 volts, more 
than enough to meet the 232 specs.

Cheers, Gene
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