First post, by fabiensanglard
I tried to upgrade my 2168 from 128K to 256K. Got a 32KiB 20ns TAG and four 32KiB 25ns chip 28 PIN dips. Also reset jumpers J16/J17 according to documentation
And the machine won't POST. After investigation, it seems that despite its name, the CY7C199-20PC TAG I got has an access time of 10ns instead of 20ns. I wonder if that could be the cause of the failure. Anybody has succesffully upgraded the L2 cache of a IBM PS/1 TYPE 2133, 2155, 2168?