I tried to figure it out but...

I have 5 MB-4D50L (OPTi chipset) mainboards which have jumper settings and sockets for either 386, 486 or 486SLC, no manual. They are equipped with a 486DX-33 which they work with. I tried to make two of them work with 386s but it didn't work, the settings of some of the jumpers for 386 are not printed on the board. (Funny thing, when pulling the 486 a socket for a 387DX will be revealed)

The one I will try to bid (none of these on ebay of course) is a MB with an integrated AMD 386 DX-40 and has a socket for either 387 coprocessor or 486 processor. It's based on Opti 82C495, has one VLB slot, 8 30-pin SIMM sockets and 128 kB cache.

Sounds similar except mine have 2 VLB slots. I can't be of any more help though.

I also have the MB-4D50L. I believe it is made by a French company called "ASI". You can get the jumper settings from TH99...BUT look for MB-4D33L instead as it has the same jumper layout. I have personally tested this board with an i386, Cyrix DLC and an IBM blue lightning upgrade. The jumper settings are nasty, but it does work fine if set correctly. The VLB doesn't work so great with the 386 chip though, it's really slow.

Thanks, it worked (I had an incident with something starting to smell but it still works - the first VLB slot didn't like a graphics card) .

Cache works with 386. Linear framebuffer works with the 386 so VLB works.

Some simple benchmarks:
386@33MHz, S3 864 graphics card, no NPU
9337 Dhrystones
171.1K Whetstones
24.9 FPS banked (vbetest 640x480x8bpp - FPS values are not too accurate as it waits for vertical retrace)
24.9 FPS linear framebuffer

386@33MHz, S3 86C805 graphics card, no NPU
18.0 FPS banked
18.0 FPS linear framebuffer

386@33MHz, ET4000/W32 graphics card, no NPU
19.8 FPS banked
30.0 FPS linear framebuffer

386@33MHz, Cirrus GD5428, no NPU
15.0 FPS banked
19.8 FPS linear framebuffer

386@33MHz, S3 864 graphics card, with 80387 NPU
2759.8K Whetstones
others as above

386@33MHz, S3 864 graphics card, no NPU, cache disabled
3315 Dhrystones
71.3K Whetstones

486@33MHz, S3 864 graphics card
16170 Dhrystones
5655.7K Whetstones
24.9 FPS banked
37.5 FPS linear framebuffer

486@33MHz, S3 864 graphics card, both caches off
3069 Dhrystones
1661.9K Whetstones
9.3 FPS banked
12.3 FPS linear framebuffer

Thanks a lot for the benchmark scores!

nice becnchmarks!!!!

I think you'll find that the VLB works much better with the hybrid 386/486 chips. I have an IBM 486DLC2-66 installed, and the thing really flies.

GL1zdA wrote:

The one I will try to bid (none of these on ebay of course) ....

Wait a second, wait a second!
What's going on?

Did I miss anything in the retro-computing life? Why not on eBay "of course"? Is there any other marketplace to look into? Is that why many old stuff are never found on eBay?

thanks!