IBM AT Drive Types

[Chris M]

The scanning frequencies of the EGA and MDA cards should be real close (MDA outputs 348 lines of res, the EGA 350). You shouldn't have a problem there (I won't comment about the jumpering/shorting though), but keep in mind the original IBM mono monitor was very very touchy. If you plugged it into a CGA card, it was known to...ummm...explode...
 I won't swear to it, but I had thought there was a way of configuring it specifically for a mono monitor. Don't hold me to it though.

Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> On this topic, I recently located an original IBM Monochrome monitor, so
> for me it's now just a matter of pulling out the EGA Techref and
> jumpering the IBM EGA card in my AT for EGA monochrome and plugging the

One thing a lot of people forget : There's a jumper on the board near the 
DE9 connector which selects where pin 2 of said DE9 goes (LSB of one of 
the colours for an EGA monitor, ground for an MDA or CGA monitor). If you 
set that to the EGA position and then connect an MDA (or for that matter 
CGA) monitor, you're shorting an output line to ground via the monitor 
cable. It probably won't do any harm, but why risk it...


-tony


		
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