Anonymous Coward wrote on 2020-01-18, 19:44:
How about a more interesting read? Specifically, the databook for the IBM SLC/DLC chips. Last time I checked it was MIA, so if you have it please share.
I have been reading up on some of your other projects (google searched a few things and some of your threads came up) - pretty neat!
I've been searching for the IBM docs forever. The only ones I can find are slightly newer, and mostly about the more modern IBM 486 chips. But, the cache document and the voltage document talk about the SLC chips.
Voltage (confirms 5v I/O tolerant, but 3.6v drive):
I've also been hunting for “IBM Corporation, 486SLC Microprocessor Data Sheet, IBM Corporation, Essex Junction, VT, 1993” which doesn't seem to exist on the Internet in any form but patent/datasheet references.
I have a BridgeBoard thread on AmiBay going here:
http://www.amibay.com/showthread.php?102965-A … PC-Bridgeboards
Undoubtedly you will have seen everything I reference below:
https://web.archive.org/web/20030708095607/ht … rand=IBM+Option
The second doc confirms the pin compatibility (IBM words):
What is an IBM 486SLC2 processor?
It is an IBM-developed derivative of the Intel 386SX chip, called the 486SLC2. The 486SLC2 processor includes the instruction set of the 486SX, rather than the 386. It only uses the same socket pin configuration as the 386SX."
I know I said Japan/European folks have been swapping for ages but it turns out that's the TI chips (ugh) - that's where I started before I found the IBM ones. I reverse engineered from a few sacrificial IBM boards (ruined by batteries) to make sure the pinout matched - from what I could tell as you can see in that image there, where the IBM SLC chips differ is that they use some of the signal lines that are "NC/not connected" on the 386sx. So it's (as far as I can tell) okay to ground those.
Apologies for saying that folks have been doing this forever, I forgot that this was a thing I spent a lot of time on on my own (long story, but I have some amnesia).