gregs@meaddata.com (Greg Smith) (12/13/90)
I have a Northgate 386/16Mz system and would like to find some way to increase the CPU performance. I have 1Mb of memory and would like to find some software to shadow my ROM and see if that helps. Is the shadowing option usually in the BIOS itself? My machine boots with the option to change the setup or do diagnostics built in (courtesy of AMI I think) but it does not offer the shadowing option. I'm also considering getting more memory. Due to motherboard considerations it will be cheapest to replace my 1MB of memory with 4MB DRAM's. Can you increase the performance by buying faster memory? Does the rating on the chip refer to the maximum, tested, error-free speed of the chip ? What controls the memory speed? Can that be upgraded so memory fetches will be returned faster? A software Engineer, a hardware literate (but not a guru), Thanks, Greg
grege@gold.gvg.tek.com (Greg Ebert) (12/13/90)
gregs@meaddata.com (Greg Smith) writes: >[...] >I have 1Mb of memory and would like to find some software >to shadow my ROM and see if that helps. Shadowing requires special hardware, as well as some customizations to your BIOS, which will be supplied by the hardware manufacturer. Here's how it works: Assuming shadowing is enabled, the system and video BIOS code is copied into RAM which has the same physical address as the BIOS. After copying, the RAM is write protected (Gee, I wonder why :-] ) and then all memory-accesses to the BIOS addresses are routed to shadow RAM, instead of going out onto the system bus. This is where the speedup occurs: Bus cycles are *required* to run at a minimum of 250nsec, whereas a local-memory access is only a fraction of this (ie, < 100nsec). > >Can you >increase the performance by buying faster memory? Generally, no. Memory cycles must be run in an integral number of wait states, and the number of wait states is usually coded into state-machines surrounding the processor. Before you flame me, I'm only talking about memory which is coupled to the processor *without* the system bus. ----- Boycott redwood products ---------------------------- Recycle ----- ##### {uunet!tektronix!gold!grege} Register to vote, then ## | ## grege@gold.gvg.tek.com vote responsibly # | # # /|\ # Support high oil prices, waste tax $$ on war, evade domestic #/ | \# problems, and die young on foreign soil- Just say YES to Bush #######
liberato@dri.com (Jimmy Liberato) (12/28/90)
In article <1792@gold.gvg.tek.com> grege@gold.gvg.tek.com (Greg Ebert) writes: > > gregs@meaddata.com (Greg Smith) writes: > >>[...] >>I have 1Mb of memory and would like to find some software >>to shadow my ROM and see if that helps. > >Shadowing requires special hardware, as well as some customizations to >your BIOS, which will be supplied by the hardware manufacturer. >... But isn't it true that the "special hardware" can simply be a 386 chip? Now if the original poster had a 286 then special hardware (Chips&Technologies NEAT chipset) would indeed be necessary. With a 386 he would only need a memory manager (QEMM 5.1, 386totheMax, DRDOS 5.0, etc.) to capitalize on the inherent memory mapping abilities of the 386. -- Jimmy Liberato liberato@dri.com ...uunet!drivax!liberato