root@grumbly.UUCP (Superuser) (03/16/90)
I have 8 megs of main memory on my SCO Unix 3.2.1 system. When it comes up it reports total memory as 7808 k instead of 8192 k. Where is the missing 384 k?
goer@sophist.uucp (Richard Goerwitz) (03/17/90)
In article <2@grumbly.UUCP> root@grumbly.UUCP (Superuser) writes: >I have 8 megs of main memory on my SCO Unix 3.2.1 system. When it comes up >it reports total memory as 7808 k instead of 8192 k. Where is the missing >384 k? Hint: Subtract your 384 k from 1024 k (the total amount of memory addressable by an 8088/6 chip), and presto, you get the answer 640 (the amount of user memory accessible via standard PC architecture). That "upper" 384 k is used by all PC's and their descendents for various things like the system BIOS, video memory, etc. -Richard L. Goerwitz goer%sophist@uchicago.bitnet goer@sophist.uchicago.edu rutgers!oddjob!gide!sophist!goer
ron@mlfarm.uucp (Ronald Florence) (03/17/90)
In article <8111@tank.uchicago.edu> goer@sophist.uucp (Richard Goerwitz) writes: > That "upper" 384 k is used by all PC's and their descendents for > various things like the system BIOS, video memory, etc. The upper 384K is used by "some" PCs. This is the startup memory of Xenix 2.3.2 on our ps2/80 with 6 mb of ram installed: mem: total = 6144k, reserved = 4k, kernel = 1340k, user = 4800k -- Ronald Florence ron@mlfarm.uu.net {yale,uunet}!hsi!mlfarm!ron
jfh@rpp386.cactus.org (John F. Haugh II) (03/19/90)
In article <RON.90Mar17104720@mlfarm.uucp> ron@mlfarm.uucp (Ronald Florence) writes: >In article <8111@tank.uchicago.edu> goer@sophist.uucp (Richard Goerwitz) writes: > > That "upper" 384 k is used by all PC's and their descendents for > > various things like the system BIOS, video memory, etc. > >The upper 384K is used by "some" PCs. This is the startup memory of >Xenix 2.3.2 on our ps2/80 with 6 mb of ram installed: > > mem: total = 6144k, reserved = 4k, kernel = 1340k, user = 4800k I used to have 2048K of memory, and POST reported there was exactly 2048K of memory, and XENIX agreed. Then I added another 2048K, and POST reported only 3712K, which is 384K shy of what one might expect. The answer, in the case of a Wyse 3216 is that the hardware can remap the 384K if you have only 2MB, but when you have more than one board it has to leave the ending address of the memory alone so the next card will start at a reasonable address. Apparently IBM did the right thing with the PS/2 and Wyse didn't. -- John F. Haugh II UUCP: ...!cs.utexas.edu!rpp386!jfh Ma Bell: (512) 832-8832 Domain: jfh@rpp386.cactus.org
bob@consult.UUCP (Bob Willey) (03/24/90)
In article <18158@rpp386.cactus.org> jfh@rpp386.cactus.org (John F. Haugh II) writes: >In article <RON.90Mar17104720@mlfarm.uucp> ron@mlfarm.uucp (Ronald Florence) writes: >>In article <8111@tank.uchicago.edu> goer@sophist.uucp (Richard Goerwitz) writes: >> > That "upper" 384 k is used by all PC's and their descendents for >> > various things like the system BIOS, video memory, etc. >Then I added another 2048K, and POST reported only 3712K, which is >384K shy of what one might expect. >The answer, in the case of a Wyse 3216 is that the hardware can >remap the 384K if you have only 2MB, but when you have more than >one board it has to leave the ending address of the memory alone >so the next card will start at a reasonable address. Well,,, You don't quite have it right. You can use all the memory (including shadow ram). There was an upgrade (about a year ago), which would allow you to utilize all the memory (get back your 384K), no matter how much memory you are using 2mb, 4mb, 8mb, etc. I know because up until about 2 weeks ago we had a Wyse 3216 in our office here, plus several in customer sites. So the answer is, YES you can utilize all the memory, you just need the right update. Hope this helps. ... bob willey ...