VOGONS


First post, by JDZero

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I apologize if this topic was covered elsewhere, and will delete this should I be directed to a thread that has already covered this.

A while ago, a co-worker gave me their old 486 computer that they had found in a house they had just bought. After a quick once over, I found a Freetech/Flexus 01-00392 Revision A VLB board inside it, sporting a Socket 3 ZIFF socket. I ended up tossing the rusted out case, and have yet to do anything with the non-functioning 3 1/2 and 5 1/4 drives, instead grabbing a different case that accommodated for vertical expansion slots (it originally came with an ISA Riser card 😜 ) --

At first I was happy to just install a 100mhz Intel 486 in there and call it a day, but recently I was able to grab a Pentium Overdrive (63mhz) CPU, and thought "What the hell?" ..

Of course, the old 486 is small has a lesser pin count than a POD, so I didn't really pay too close attention until I got the CPU in, and then I discovered that two of the pin holes had a wire installed in them. From looking over the pin layout of a Socket 3, the two pin holes that are wired together are S1 (VSS) and T1 (WB/WT) =

My questions:

Question 1 - Has anyone come across this sort of setup before?
Question 2 - Is this important for the Socket functionality?
Question 3 - Can it be removed safely in case it isn't important?

Reply 1 of 5, by cyclone3d

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The WT/WV one was to force the cache mode setting for the CPU. The other one may have been to make a CPU work on the board that was not officially supported...or maybe they were hoth for the cache setting.

Should be able to be removed but I would remember the wire mod in case you ever want to put it back the way it was.

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Reply 2 of 5, by JDZero

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cyclone3d wrote on 2026-07-08, 00:23:

The WT/WV one was to force the cache mode setting for the CPU. The other one may have been to make a CPU work on the board that was not officially supported...or maybe they were hoth for the cache setting.

Should be able to be removed but I would remember the wire mod in case you ever want to put it back the way it was.

Thanks for the fast reply!

Well, I'll see if I can even properly remove it without breaking anything. Noting the bridge location, at least I'll have a picture reference.

Reply 3 of 5, by jakethompson1

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See pages 95-100 of https://theretroweb.com/misc/documentation/29 … d9447018695.pdf
In particular on page 97, it addresses the issue that INV, HITM#, CACHE#, WB/WT#, INIT, and FERR# move to a different place on the POD vs. the P24D. Their recommendation is that the motherboard connect the two locations together, but if your board doesn't do this (my EFA 4DMS-HL3G doesn't do all of them either) and doesn't provide a jumper for both the POD and P24D version, the wire you found might have been a workaround.

Grounding WB/WT# forces the POD into write-through, suggesting the prior owner couldn't get write-back working. If you consult the pinout differences in the above datasheet, it's possible that you can use a multimeter and additional wires to connect all the write-back related pins to their proper places and get it working.

Reply 4 of 5, by Matth79

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Doesn't look like the CPU pins would go in. It's taking up the entire holes - POD would be blocked.
Appears it may be a bodge to force a 486 with WB to use WT mode

Reply 5 of 5, by JDZero

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So I went ahead and removed the bridge wire - it's just a drop-in mod (You could easily remove it with your fingers if you could grip it) - And yeah, as Matth79 said, it cannot be used with a POD, due to the pin alignment.

As far as the mode goes, I would need to look at the 486DX2 that it came with to see what why they added the bridge. I dropped in a DX4-100 about a month ago (I'll eventually make a thread for the PC build), and so far it seems to be fine? I may try to remove it again to see if there's any actual difference.