patrick@cos.UUCP (05/15/87)
I recently bought an AT-clone. When I bought it I was told
by the seller that "It was probably more usefull to get 640K put on
my motherboard rather than 1Meg". He went into several reasons, but
because I don't think I understood them I will not try to rephase them.
My question stems from a inconsistency in logic (phrased below):
Given that:
I thought on the IBM PC/XT that the space between 640K and 1Meg
was used for various peripherals, and as such was not
"generally useable".
So I deduced that:
Because the AT is very compatible with the PC/XT, the AT also
uses the space between 640K and 1Meg for various peripherals,
and so the space between 640K and 1Meg is not "generally usable"
SO NOW, I have the problem that:
If you stick 1Meg into an AT, How does the AT "use" the space
between 640K and 1Meg???? Confussion sets in :^)
My question is:
If the AT motherboard is stuffed with 1Meg of RAM is the RAM split
up into two physically addressable areas (i.e., 0-512K, and 1000K-1500K,
or 0-640K, and 1000K-1340K)?
Ok. So maybe my question is stupid, maybe I should learn more about the
AT... but, please don't insult me any more than you feel it is deserved.
Please send responses directly to to me. If I more than a handfull of
interested people I will post the answer(s) I have received.
patrick (Patrick Steranka @ Corporation for Open Systems)
-- patrick@cos.com
-- {seismo!sundc, hadron, hqda-ai}!cos!patrickgeller@eli.UUCP (David Geller) (05/16/87)
My experiences with placing one Mbyte of RAM on an AT clone has been upsetting. My system (clones that we assemble) do not like the extra address area filled. When placed with RAM (the best brands, various speed) parity errors (NMI, etc) would pop up often - especially with a Princeton Graphics (Cannon) LS-300 scanner and Wyse 700 monitor installed. The scanner is a DMA device with its own card (what else, right - ether DMA...) Anyhow - the system works like a champ with a measly 640K RAM. David Geller UUCP: ..!seismo!sundc!eli!geller Electric Logic, Inc. Telex: 6503003778 2025 Eye Street, N.W., Suite 220 MCI Mail: PRESS Washington, D.C. 20006 Compuserve: 72667,1312