Can you give other examples of boards that can use your upgrade module?

I have ordered already something exotic that probably has the same layout.
I do not want to throw spoilers at people. I will make a video about that.
Either-way for me it is very simple to modify the adapter and reorder.

I remember when I was younger I had always heard about how there existed 386SX systems with removeable CPUs. I would often rummage through junk bins in used computers stores looking for such a motherboard. This was before eBay listings had many pictures, and search engines didn't have an image search, so the ability to locate such things was extremely limited.
Even today, finding such a board is rare. From what I can tell, the majority of boards configured this way were in OEM systems. Every time I find a board like this on eBay, I try to document it. Needless to say, I haven't found too many. But during my searches, I occasionally noticed a 386SX board with solder pads for what looked like a test socket...but the pinout never seemed to be very consistent.
One day over 15 years ago I managed to purchase several desoldered 386 QFP100 test sockets that had a staggered pinout. I searched for a long time for a board that I could solder one onto. I think in all my searching I only ever found 1 or 2 boards that looked like they might accept my sockets, but I think both of them were very old and not worthwhile.
There are at least 4 or 5 pinouts for 386SX test sockets that I am aware of. They all seem to be about equally uncommon. I think I may have seen the one on your M396 on perhaps one other board. The most common one I run into is used by the military grade 386SX in PGA, which is also extremely rare.

DTK 386sx systems came in a socketed cpu version

whaka wrote on 2022-05-02, 20:00:

ohhh i realize i didn't put my contribution here. i successfully upgraded 2 PS/2's with SXLC2 50 and 40 Mhz chip. […]
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ohhh i realize i didn't put my contribution here.
i successfully upgraded 2 PS/2's with SXLC2 50 and 40 Mhz chip.

first is a model 35 (isa) originally with a SX20, successfully upgraded with the SXLC2 50 G50 (without 3,3v mod) , overclocked to 33 MHz. and for bonus, cache is enabled by bios.
and clock doubling work with software control, and 66 MHz is possible totally reliably. but i added a heatsink, clock doubling also mean heat doubling 😀.

second is a model 55SX (mca) originally SX16, successfully upgraded with the 40 Mhz (so real 5V part) , tried overclock to 20 MHz but fail. cache is enabled by bios.
clock doubling doesn't work, the machine crash. don't kno

- model 55SX
hi, i'm also modifying an ibm 55sx by mounting a 486-50 processor.. i wanted to ask.. how far can i put the quartz of the clock without the system exploding?!?!?!?

hi, i'm also modifying an ibm 55sx by mounting a 486-50 processor.. i wanted to ask.. how far can i put the quartz of the clock without the system exploding?!?!?!?

The timing test in the BIOS fails on a 55SX for any speed crystal above ~18Mhz... i.e. it complains and won't boot.

edit: for clarity, it's a double speed crystal, that means you can't replace the 32Mhz with a 40Mhz, but a 36 might be okay and a 38 is a coin flip depending how warm or cold the system is at boot.

ok.. so I have to put a quartz no higher than 36Mhz.. with the 486 I hope to get some benefit..

even without overclock you'll get a substantial benefit, the cache by itself is already a good improvement.
and as i said it's enabled right at boot 😀

386—>486 build

This is my 386 upgrade thread :p

Curious if anyone else has any ideas why I can’t get clock doubling to work?

Sorry to revive this thread. I am going to upgrade a 35sx ISA with a Ti486sxlc2-G50 and was wondering how your mod is doing? Did you had any problema this far? Can i do a pure swap or do i need to mod it to give 3.3v to the core?

whaka wrote on 2022-05-02, 20:00:

ohhh i realize i didn't put my contribution here. i successfully upgraded 2 PS/2's with SXLC2 50 and 40 Mhz chip. […]
Show full quote

ohhh i realize i didn't put my contribution here.
i successfully upgraded 2 PS/2's with SXLC2 50 and 40 Mhz chip.

first is a model 35 (isa) originally with a SX20, successfully upgraded with the SXLC2 50 G50 (without 3,3v mod) , overclocked to 33 MHz. and for bonus, cache is enabled by bios.
and clock doubling work with software control, and 66 MHz is possible totally reliably. but i added a heatsink, clock doubling also mean heat doubling 😀.

second is a model 55SX (mca) originally SX16, successfully upgraded with the 40 Mhz (so real 5V part) , tried overclock to 20 MHz but fail. cache is enabled by bios.
clock doubling doesn't work, the machine crash. don't know why.

some pictures :

- model 35

- model 55SX

as i said, i use it with 5V. i put a little heatsink on it as it run hot at clockdoubled frequency.
i just clocked down from 33 to 30 because i got some crash from time to time.

overclocking also give an issue with mouse and keyboard hanging at boot with windows 3.x. don't know why, but it's only with 3.x.
no issue with DOS, 95 or OS/2.
maybe it's just my machine, but if you can try and report it'll be appreciated 😀

Is everyone who can't run the clock past 33Mhz using a heatgun to solder the chip?

I've soldered two Ti486SXLC-50's using a soldering iron & flux. One I only tested at 33Mhz (66Mhz double clocked), the other ran at 100Mhz double clocked...

MikeSG wrote on 2024-09-06, 14:54:

Is everyone who can't run the clock past 33Mhz using a heatgun to solder the chip?

I've soldered two Ti486SXLC-50's using a soldering iron & flux. One I only tested at 33Mhz (66Mhz double clocked), the other ran at 100Mhz double clocked...

It’s a thought… but in theory a unpowered chip should survive. The components are supposed to be able to survive SMT techniques.. mind your temperature.

Some chips are moisture sensitive and can't handle heat much above operating temperature... The Ti486SXLC isn't labelled as such, but I can't think of another explanation.

There's is a potential keyboard controller problem with boards using the old 74F04 hex inverters. Newer controllers recommended the open-collector type. 7406.

Dear member,

Can I conclude here that I can use a 486SXLC2-G50-PQ to solder on my 386sx mainboard which has the qfp 386sxl 25 AMD on it (without any voltage mods)?
A short confirm and I will also start this project 😀

Thanks

BTW I have since found out that the 6th Edition of Muellers Upgrading and Repairing PCs has debug code for patching an IBM PS/2 BIOS to ignore the speed check.

Marco wrote on 2024-12-23, 07:24:

Dear member,

Can I conclude here that I can use a 486SXLC2-G50-PQ to solder on my 386sx mainboard which has the qfp 386sxl 25 AMD on it (without any voltage mods)?

looks like G50 requires 3.3V supply?

Indeed but people here state that with heatsink it is running fine. I hope this can be confirmed because these pure 5V versions (050) are nowhere to find.