First post, by feipoa
Does anyone have detailed information on the UMC UM8881F Northbridge chip sub-revisions?
It appears that not all UM8881F chips support the same features. The identifier following the datecode appears to be a sub-revision. About 12 years ago I hard ordered some spare UM8881F chips and specified a datecode of 1997+. Unfortunately, what arrived in the mail were chips with a datecode of 1995. Last week, I replaced the the UM8881F 9651-EYA chip on my PC Chips M919 with a UM8881F 9527-BTS chip. The options in the BIOS to select between EDO and FPM disappeared, as did the option to enable the Cyrix Cx5x86 Linear Burst mode. Attempting to use EDO memory with the -BTS chip doesn't work (screen goes blank after POST). Attempting to use Linear Burst mode results in a full system hang-up.
Curiously, and if my memory is correct, my Shuttle HOT-433 (early versions 1-3) contained the UM8881F Northbridge with datecode 9527-BCT and it had no problem with EDO memory, so I am confused why the M919 doesn't like EDO now that I've changed northbridge. I remember reading in the unofficial PC Chips M919 manual that an -E** was needed following the datecode for EDO to work, but this doesn't appear true for the HOT-433.
Perhaps someone has some detailed information on these UM8881F sub-versions?