boerner@ut-emx.UUCP (Brendan B. Boerner) (06/04/89)
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? Brendan ------------------ Brendan B. Boerner Phone: 512/471-3241 Microcomputer Services The University of Texas @ Austin Internet: boerner@emx.utexas.edu UUCP: ...!cs.utexas.edu!ut-emx!boerner BITNET: CCGB001@UTXVM.BITNET
shawn@pnet51.cts.com (Shawn Stanley) (06/05/89)
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