On 14 Mar 98 at 20:12, Rick Poepping wrote:

> > 1. Do I have to purchase a new case due to the incompatible AT and ATX
> > standards?
>
> Definitely! At the very least the cards are rotated 90 degrees on an ATX
> versus an AT.

  That's one way to look at it, but I think this description could
confuse anyone who has never seen an ATX board.

  On an AT board, the CPU is usually between the slots and the front
of the case, and so its fan may prevent installation of full-length
cards (there are still some around...) in as many as 3 or 4 slots.

  An ATX motherboard extends for about 6" past where the AT keyboard
connector would be, and so the board is often not much "deeper" than
the length of the slot connectors.  CPU and RAM are generally in the
area between Slot 1 and the poser supply.  [ATX poser supply cooling
is designed assuming the CPU will be in this area.]

  So if you align the slots of an ATX board over those on an AT board
of similar features, you'll find that the AT board extends toward the
front of the case, and the ATX extends twoard the power supply.
  The orientation of the slots within the case is still the same;
that's why I think saying that "the cards are rotated 90 degrees" is
a confusing description.
  [There is another new "low profile" form factor, NLX, in which
expansion cards are installed parallel to the motherboard into a
"riser" card, as they were on the PS/2-30 and various compact designs
since.  You could say that in that sort of design "the cards are
rotated 90 degrees", but it's not ATX.]

David G