Today I repair and test a budget model FIC 486VCHD motherboard. This board refused to boot due to a dead RTC module, but also had terrible memory latency. Join me today as I get this board repaired and dig into a surprising caching problem that impacts many 486 boards from the early 90s.

DS12887A+ RTC modules from DigiKey:
https://www.digikey.ca/en/products/de...

24pin DIP sockets:
https://www.digikey.ca/en/products/de...

Necroware’s nwX287 modules:
https://github.com/necroware/nwX287

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00:00 Introduction
00:34 It’s Broken
01:47 RTC Replacement Options
02:23 Replacing the RTC Module
04:48 Terrible Memory Performance
06:01 Disabling the L2 Cache
06:23 L2 Cache Configuration
07:14 The Dirty Bit
09:37 Adding AlterRAM
10:07 An Expensive Mistake
11:24 Conclusion