First post, by Tymo486DX2

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I am looking for all the best UMC chipsets on 66Mhz host bus.
I mean full list of UMC (only) chipsets.
Does anyone have list like that?
Can You send some links?

I am interested in 66Mhz for host bus and IDE (EIDE) double controller &
four ports of RAM - 72pin EDO RAM
128 MB each one, together 512MB RAM handling on the board.

EIDE controller at 66MHz too. Ultra ATA 66.
Only UMC brand.

Does anyone knows desc of that chipset or full motherboard mark?
I have read that it is ever possible to work with UMC board at 66Mhz boards.
I have about 10 motherbords with UMC chipsets but I am not sure which one is the best and if it will work with full demand features.


Route 66 MHz😎

Reply 1 of 4, by Horun

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Do not know. You will not get any VLB IDE card running 100% stable at 66Mhz even with wait states AFAIK. Know of no ISA or VLB "EIDE controller at 66MHz too", not one was "Ultra ATA 66" because that came out in 1999 way after VLB so that leaves only PCI. Oh and am fairly sure that PCI standard was 33Mhz not 66mhz on 486, first pci-66mhz spec release was 1995 but implimented until later so doubt you will find 66mhz PCI on any 486 board. Good luck !
oops bad gramar

Hate posting a reply and have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. 🤣 Second computer a 286 12Mhz with real IDE drive ! After that came 386, 486, Pentium, P.Pro and everything after....

Reply 2 of 4, by Anonymous Coward

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As for graphics cards, I was able to get my ARK1000VL cards working at 66MHz with 1ws. At that speed you definitely don't want any other VLB devices anyway. Best run your disk controller on ISA/EISA/PCI.

"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

Reply 4 of 4, by amadeus777999

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Support won't do much - you'll have to test if it's really working.

The UM888x boards that I tested were "perfectly" stable at 50mhz(+fastest timings) but after that things started falling apart. Timings is the main issue - pumping at high frequencies but with delay counts only to end up marginally faster or even slower is a bit fruitless.