langston@convex.COM (Kevin Langston) (10/31/90)
I just learned that the Micronics 386/33 reserves the 384K chunk whether you tell it to use shadowing or not. I am running 386 Xenix 2.3 and I would like to know if there is any performance to be gained by using this memory for BIOS shadowing under a protected OS, or does Xenix duplicate the BIOS functionality some other way? Thanks for any tips, suggestions, or meaningful explanations, -- |From the| Kevin Langston @ Convex Computer Corporation, Richardson, Texas |virtual | UUCP: {uiucdcs,_______,sun,uunet,harvard,rutgers}!convex!langston |desk of | OR: langston@convex.COM "A conclusion is merely a place holder." ========== "Oh, I'm sorry. Was that out loud?" Cliff on _C_h_e_e_r_s =============
pgd@bbt.se (11/01/90)
In article <107963@convex.convex.com> langston@convex.COM (Kevin Langston) writes: > >I just learned that the Micronics 386/33 reserves the 384K chunk whether >you tell it to use shadowing or not. I am running 386 Xenix 2.3 and I would >like to know if there is any performance to be gained by using this memory >for BIOS shadowing under a protected OS, or does Xenix duplicate the BIOS >functionality some other way? > >Thanks for any tips, suggestions, or meaningful explanations, I don't think that is true. We have machines with four different versions of Micronics motherboards. (one old TTL 20MHz, one newer 20Mhz, one TTL 25MHz, and some ASIC 25MHz) None of them reserve the shadow RAM specially. So I find it very unlikely that a later model, the 33MHz motherboard does that. They all have dip-switches to reserve memory, but Xenix is ignoring all that, and is using all memory. You can easily see how much memory Xenix is using, at boot time. Compare that with the amount of memory you know you have in the machine. (Check the "total memory" number) Xenix is using the bios only for booting. After that it is completely ignored. Everything the bios is doing, is done by the xenix kernel.
shwake@raysnec.UUCP (Ray Shwake) (11/04/90)
pgd@bbt.se writes: >I don't think that is true. We have machines with four different >versions of Micronics motherboards. (one old TTL 20MHz, one newer >20Mhz, one TTL 25MHz, and some ASIC 25MHz) None of them reserve the >shadow RAM specially. So I find it very unlikely that a later model, >the 33MHz motherboard does that. They all have dip-switches to reserve >memory, but Xenix is ignoring all that, and is using all memory. Don't know if this is universally the case. I'm running Xenix/386 on an NEC 386/20 (C/T chipset, Phoenix BIOS) which reserves 384k. Neither Xenix nor ISC UNIX (which I also run on this box) access this memory, as verified at boot time. Of course, if someone *does* know a way to access this memory, please advise!
karl@robot.in-berlin.de (Karl-P. Huestegge) (11/06/90)
shwake@raysnec.UUCP (Ray Shwake) writes: > Don't know if this is universally the case. I'm running Xenix/386 >on an NEC 386/20 (C/T chipset, Phoenix BIOS) which reserves 384k. Neither >Xenix nor ISC UNIX (which I also run on this box) access this memory, as >verified at boot time. Of course, if someone *does* know a way to access >this memory, please advise! Sorry, there is no way to access the 384k. The 386 C&T chipset doesn't support this. You only have an advantage under DOS with the shadow ram. -- Karl-Peter Huestegge karl@robot.in-berlin.de Berlin Friedenau ..fub!utopia!robot!karl