heres a pentium OD socket for you: http://www.mpja.com/ZIF-Socket-168-Pin-Grid-S … nfo/11436%20IS/

AFAIK that's a Socket1, 168 pins, for the 486 OD series. Unfortunately not the 237/238 pins necessary for the Pentium OD.

Nice project

ah, well thats a horse of a different color. Sadly, I dont have a cheap easy solution, but I found a company that at least pretends to make a 237/8 pin 19x19 socket. It isnt a easy lever style but the hard to remove version.

http://www.arieselec.com/products/data/14033- … cket-header.htm

I would guess making one or two will NOT be very cost effective, but if you order a box of them, maybe you can re-sell them on ebay for other people looking for sockets. Its that or you de-solder one off another board. 🙁

If you need some Pentium instructions but don't want to mod the socket, maybe try one of the Cyrix 5x86 CPUs.

I considered the Cyrix chips but they would likely have a similar issue since the CPUID instruction is disabled in them by default.

Besides I already have the Pentium OD on hand and I'm not one to let good hardware go to waste. I also managed to find a source for new cheap-ish PGA169 and PGA237 LIF (aka "no lever") connectors. That was, afaik, the biggest challenge in the entire project. 😁

I'll keep you guys updated on the progress in the next few weeks when the parts arrive.

Took much longer to reply than expected due to travel over the holidays, sorry.

End result? It works great! External cache is completely disabled though, must have forgotten a line somewhere. I'll have to comb through the Pentium Overdrive datasheet again.

Still, completely home-made Socket3-Socket1 interposer: victory. 😁

If there's interest, I'll take a few pictures.

Maeslin wrote:

Took much longer to reply than expected due to travel over the holidays, sorry. […]
Show full quote

Took much longer to reply than expected due to travel over the holidays, sorry.

End result? It works great! External cache is completely disabled though, must have forgotten a line somewhere. I'll have to comb through the Pentium Overdrive datasheet again.

Still, completely home-made Socket3-Socket1 interposer: victory. 😁

If there's interest, I'll take a few pictures.

In fact I DEMAND pictures. Also full details of how you did it. Also, if you feel up to it and want to make a project for me regarding adding L2 cache to a 68040...

I would like to see some pictures. I am a big fan of the Pentium Overdrive, I have a bunch of the 83mhz versions and two of the 63mhz versions. I also like single board computers, I have one sitting in a passive backplane in an industrial computer that is a Pentium 200MMX, I've only used it to play DOOM. I have plans to overclock some of the 83mhz Overdrives to 100mhz and study their behavior and compare to Socket 5 Pentiums and Socket 4 Pentiums.

Maeslin wrote:

Took much longer to reply than expected due to travel over the holidays, sorry. […]
Show full quote

Took much longer to reply than expected due to travel over the holidays, sorry.

End result? It works great! External cache is completely disabled though, must have forgotten a line somewhere. I'll have to comb through the Pentium Overdrive datasheet again.

Still, completely home-made Socket3-Socket1 interposer: victory. 😁

If there's interest, I'll take a few pictures.

Definitely I'd want to see some pics of that little piece of hardware magic you concocted 😁

Also interested in seeing pictures of your concoction. 😀

I thought it was already established that an interposer was not really required to use a POD83 in a 168pin socket. It seems all the extra pins were just grounds or something.

Mostly power and ground pins, a few POD83-specific ones as well as 7 or 8 that are moved around from their normal '486' position and that are pretty important (reset signal, init signal, cache type control, etc.). You'd have to reroute those or risk getting very odd results / have the chip in an undefined state.

I also needed the vertical clearance given by an interposer otherwise the extra pins of the POPD83 would have been touching other components. :p

Tetrium wrote:

Maeslin wrote:

Definitely I'd want to see some pics of that little piece of hardware magic you concocted 😁

After much delay, here are the shots. and a few explanations.

I used the original Intel datasheets on the 486 as well as the datasheet of the POPD83 Pentium Overdrive. The latter contains a very convenient comparative diagram of pinout differences, what the new ones do and which should be routed where for mismatches. Copied the whole thing in Altium, measured the socket pin dimensions with an electronic caliper, adjusted a few things (hole sizes, etc.) and connected traces as required. Unfortunately write-back cache cannot be enabled as there are a number of write-back-cache-specific signals present on Socket3 which have absolutely no analog on Socket1.

4-layer PCB made by OSHPark, with Ground and VCC planes tying all the power pins together. Holes in the PCB were made large enough to fit around the 'wide' section of the socket pins, making it completely unobtrusive. Outer pins of the Socket3 were cut flat at the neck and soldered in the adapter PCB. Matching pins of the Socket 3 were left full length, their wide sections carefully soldered to the PCB and the remainder of their pins (the full useable length) inserted in the Socket1.

Honestly? Finding the damn sockets was the hardest part of the whole project by a long shot. 😵

From the top:

From the bottom:

From the side, P54D CPU removed:

From the side, CPU inserted:

Where did you find the 237 pin socket? I've looked in the past, but always came up empty handed.

Anonymous Coward wrote:

Where did you find the 237 pin socket? I've looked in the past, but always came up empty handed.

Wow, sorry it took so long to notice this reply 😵

Here's the exact socket I used. Got 5 of them in case I screwed up so I still have a few on hand.: http://www.questcomp.com/questdetails.aspx?pn … nid=218455&pt=0
http://www.questcomp.com/questdetails.aspx?pn … nid=218798&pt=0 should be a valid alternative as well.

Sorry to necropost but thought someone might want to see the original images posted by Maeslin
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