WTD: AT&T 6300 Personal Computer mother bd dip switch map

[Jim Leonard]

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 oldskool.org)            http://www.oldskool.org/
Help our electronic games project:           http://www.mobygames.com/
Or check out some trippy MindCandy at     http://www.mindcandydvd.com/
A child borne of the home computer wars: http://trixter.wordpress.com/