Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!ames!xanth!nic.MR.NET!shamash!nis!sialis!orbit!pnet51!shawn
From: shawn@pnet51.cts.com (Shawn Stanley)
Newsgroups: comp.sys.ibm.pc
Subject: Re: what to do about 384K of extended memory?
Message-ID: <786@orbit.UUCP>
Date: 4 Jun 89 18:05:10 GMT
Sender: root@orbit.UUCP
Organization: People-Net [pnet51], Minneapolis, MN.
Lines: 29

boerner@ut-emx.UUCP (Brendan B. Boerner) writes:
>Suppose you bought a computer, such as an IBM PS/2 Model 60 for
>instance, which comes with 1Meg of RAM.  You then have 640K of
>conventional memory and 384K of extended memory.  What happens when
>you buy another 512K or 1024K of extended memory?  As far as I can
>tell, when adding extended memory, you can only set the DIP switches
>(for non PS/2 memory boards) at every 512K mark.  It would seem that
>you could a) set the board to start at address 0x180000 (1.5Meg mark)
>and leave a hole between the end of the 384K which starts at the 1Meg
>mark and the added extended memory, i.e. a 128K hole between 0x120000
>and 0x180000 or b) set the board to start at 0x100000 and lose the
>384K.  Can anyone please confirm, deny or clarify this?

I think it depends on your software (and your hardware, but you've covered
that).  For instance, I used to use a Dell machine that had 384K that could be
used in many different ways from MS-DOS, including swapping the BIOS into it
to speed up the system.  Also, the memory was visible to SCO Xenix, thus I had
a base of 1Mb to work with.  (The system shipped with 1Mb; we got another Mb
later on.)

However, my CompuAdd system has 384K of the original 1Mb that can't be used by
SCO Xenix, although its uses are similar through MS-DOS to the Dell system. 
When another 1Mb is added, I end up having a 1640K SCO Xenix system out of a
2Mb total on the system memory board.

I'm not sure what OS/2 would do with the system.

UUCP: {uunet!rosevax, amdahl!bungia, chinet, killer}!orbit!pnet51!shawn
INET: shawn@pnet51.cts.com