lane@cs.dal.ca (John Wright/Dr. Pat Lane) (03/08/90)
Here's a question Qualitas tech support couldn't answer, at least not
to my satisfaction.
I have a Cache-32 NEAT 286 with a Chips & Technologies chip set and a
AMI BIOS. There's a 80387 and I'm running DOS 4.01. I recently
installed 386MAX ver 4.05. If you have over 640K installed in the
machine, the C&T chipset automatically reserves 384K for ROM shadowing.
(so on a 2 Meg machine you get 640K base RAM and 1024K of extended).
The ROM shadowing can be turned on or off for segments C000-C3FF,
C400-C7FF and F000-FFFF, a total of 96K.
My question is what do they do with the other 288K! And if they do
something important with it, what do they do if there is less than
1Meg in the machine and the memory isn't physically there.
You can turn all ROM shadowing off but you still don't get the 384K
back. Now 386-to-the-Max (a great addition to any 386, BTW) can get
*some* of this back (you have to specify the "SHADOWRAM" keyword on
the 386MAX.SYS line) but on my system it only gets 176K back and it
uses some of that for its own ROM shadowing scheme. Again, I ask:
where does the rest of the RAM go (208K in this case)?
The Qualitas person opined that the Chipset/BIOS needed it for its own
nefarious purposes but that led to my question as to what that might be
and what happened if you had a 512K or 640K machine without any extra RAM.
Thanks for any enlightenment.
--
John Wright ////////////////// Phone: 902-424-3805 or 902-424-6527
Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8
Cdn/Eannet:lane@cs.dal.cdn Uucp:lane@dalcs.uucp or {uunet watmath}!dalcs!lane
Arpa:lane%dalcs.uucp@uunet.uu.net Internet:lane@cs.dal.caphil@pepsi.amd.com (Phil Ngai) (03/09/90)
In article <1990Mar8.004459.19945@cs.dal.ca> lane@cs.dal.ca (John Wright/Dr. Pat Lane) writes: |My question is what do they do with the other 288K! And if they do |something important with it, what do they do if there is less than |1Meg in the machine and the memory isn't physically there. I'm not going to take the trouble to add up all 288K of your bytes for you but you can get started by realizing that shadow RAM, while it can be used, can not be relocated. If there is a resource at a shadow RAM address which can not use shadow RAM, then that S.R. can not be used at all. For example, if you have VGA, then all of the A000-BFFF (128 Kbytes) is used for the video display memory and all of that S.R. is totally useless. In summary, C&T's decision to force you to use shadow RAM was not in your best interest. |The Qualitas person opined that the Chipset/BIOS needed it for its own |nefarious purposes but that led to my question as to what that might be |and what happened if you had a 512K or 640K machine without any extra RAM. This is a complete airhead type of answer. I expected better from Qualitas. I would certainly recommend Qualitas 386Max over QD QEMM-386. -- Phil Ngai, phil@amd.com {uunet,decwrl,ucbvax}!amdcad!phil A PC without DESQview is like Unix without ^Z.