Hello, just wondering, if I were to replace the 20 ns cache with 15ns cache, will it make a major difference on performance on the ram timings?
will the tag ram need to be faster than 15ns should I upgrade?
On a 40MHz 386 board, I can generally set the fastest cache timings with 20ns cache, but if you're running a 486 then 15ns cache might help you tighten things enough to see a measurable performance increase.
"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium
From the info I could gather a 15ns cache is able to be driven at 40mhz with the fastest settings. So 20ns caches may play along at 33mhz at the tightest timings. In theory it could work at 50mhz but that's of course hypothetical.
It does also depend on how many cache banks you have. Often a dual bank offers higher performance with similar spec'd cache rams which means you can have faster settings with chips having identical latency when compared to a single bank system.
Mode, as in Writeback or Writethrough, also matters - latter often enables more aggressive settings.
Then there's also the quality of the ICs - by accident I have acquired Cypress srams which withstand higher speeds then both the generic chinese- and authentic Winbond -12ns ones. Albeit these seem to be from a select batch that also bears slightly different type codes.
In short, experiment.
