-=> /* Quoting Murray Lesser to Frank Sexton */ <=-
 ML> I don't think there ever were a set of "official AT
 ML> specs" - at least not published by IBM.
 FS> How was IBM able to build more than one machine the
 FS> same if there were no specs?  I thought they had XT
 FS> specs and AT specs that they went by and that these
 FS> were eventually adopted by "clone" makers.
 ML> Hi Frank--
 ML> Strictly speaking, you are correct.  Most certainly,
 ML> IBM had/has internal specs for their products.  What I
 ML> should have said: IBM never published the full PC/AT
 ML> specs externally, except (probably) as non-disclosure
 ML> documents for patent licensees.
Either way, the only point I was making is that 03f8
(COM1-IRQ4) and 02f8 (COM2=IRQ3) are specified in those
specs and are generally adhered to by all software I've
seen as well as all hardware I've seen.  That cannot be
said for the COM3 and COM4 addresses of 03e8 and 04e8 since
there were only two com ports in the original XT/AT specs.
Therefore the fact that some video cards interfere with
02e8 (COM4) is not recognized by the video card
manufactures as a bad thing on their part.  If the video
card interfered with COM1 or COM2 I'm sure they'd fix it
quick.  That's the only point I was making.  The COM4
interference isn't seen by the video card manufacturers as
their problem.  It is left up to "us" to work it out if
necessary.  For me that ment selling a few video cards with
this problem and replacing them with others.  A real PITA.
-Frank
(fsexton@xpert.net - http://www.concentric.net/~fsexton)
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