Tony Duell wrote:
Hi - I am
attempting to install a CGA card onto a AT&T 6300 Personal
Computer. It currently has only a 25-pin CRT port for a terminal dumb
terminal (w/o keyboard). I need the dip switch map so I can set for the
If that's the machine I think it is, that DB25 is _not_ for a terminal.
It's not a seiral port, it's not a parallel port, it's video output for
special Olivetti monitors. IIRC there are power lines (at least +12V --
the runoured 70V is a myth!) there as well to power a monochrome monitor.
Bingo, that's right. And more sad news for the OP: You cannot install
a CGA card in an AT&T PC 6300 (or Olivetti M24 for that matter). There
are electronics on that card that are necessary for the operation of the
machine.
There were EGA cards released that were "compatible" (meaning, inserting
them disabled the onboard CGA) but those are few and far between. There
was a hardware hack for adding VGA but I've lost it due to time.
The DB25 pinout for the monitor is here:
http://www.hardwarebook.net/connector/av/attpc6300.html
AT&T isn't CGA either; it's 640x400, so I'm not entirely sure if
building a db25 to db9 would work... but you could certainly try, since
there are 1-to-1 mappings of CGA to the 25 pins in that connector (8 of
them are GND for example).
--
Jim Leonard (trixter at
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