I’m guessing memory timing or a bad chip

Have you tried an actual 386dx ?

rmay635703 wrote on 2022-06-29, 18:31:

I’m guessing memory timing or a bad chip

Have you tried an actual 386dx ?

Yes, I tried a 386DX, a different 486DLC, and the jumper settings for 80386DX vs. CX486DLC. None of it made a difference.
I also tried all combinations of memory/cache settings, from 0-3 wait states. And multiple sets of 4x4mb 60ns modules.

I too gave up on that dream - I had an EISA VLB 486/386 board, worked perfectly with the 486, would not take any form of 386 no matter what. At least you've got a manual for yours. I now have an IBM PS 1000 with a Blue Lightning chip in it 😁

My BIOS had (under advanced options) a "Enable 386" mode (or it may have said DLC too) - look around in there perhaps.

Jed118 wrote on 2022-06-29, 18:58:

I too gave up on that dream - I had an EISA VLB 486/386 board, worked perfectly with the 486, would not take any form of 386 no matter what. At least you've got a manual for yours. I now have an IBM PS 1000 with a Blue Lightning chip in it 😁

My BIOS had (under advanced options) a "Enable 386" mode (or it may have said DLC too) - look around in there perhaps.

Man, sorry to hear. Seems some builds just aren't meant to be. When it comes to 386/486 VLB boards, I've already missed/lost several auctions, even had other buyers beat me to buy-it-nows.
Nice PS/1000, I watched your video on it just now.

No sign of "Enable 386" in the BIOS unfortunately. Perhaps it's a hidden option... if anyone on here has a ROM programmer, I could maybe send you the board to play with.

I'd like to kindly direct you to the listing for your board on The Ultimate Retro

https://www.ultimateretro.net/en/motherboards/1383

Please stop linking to stason. UR is a community project run by guys from this very forum

AT bus clock CLK2IN/6 is too fast I believe. CLK2 would be 66 or 80 MHz for a 33 or 66 MHz 386, so 11 or 13 1/3 MHz. You want CLK2IN/8 or CLK2IN/10 if you have those...
A 486 doesn't use the double-speed clock which might make a difference...

Hmm is it actually ok to jumper the board for 128K cache yet have all 8 chips in? I would make the jumpers match that it's 256K double bank...

CLK2IN/8 is the lowest it goes. I tried CLK2IN/4 and /8, but it makes no difference. With either setting I can boot to Win95 and the sound card works (but memtest fails), so maybe they meant CLKIN instead of CLK2IN.

I tried both 128K and 256K jumpers, and enabling/disabling the cache in BIOS. Still failing memtest.
One option I haven't tried is Non-Cache Size Block and Non-Cache Address Block 1 and 2. The settings are 64kb, 128kb... up to 8192kb. Anyone know what this does?

I always wonder if I can install 386 and 486 CPU at the same time and just use jumpers to decide which to use?

Xeen wrote on 2022-07-23, 10:14:

I always wonder if I can install 386 and 486 CPU at the same time and just use jumpers to decide which to use?

That usually only works with a soldered cpu on a board meant to support

Otherwise

Installing NT4 on 386 is pretty optimistic by any standard.

Try adding a FPU for test.

kixs wrote on 2022-07-23, 17:23:

Installing NT4 on 386 is pretty optimistic by any standard.

Try adding a FPU for test.

I didn't think NT 4 ran on a 386 at all because of COMPXCHG. But maybe the uniprocessor kernel does?

rmay635703 wrote on 2022-07-23, 15:35:

That usually only works with a soldered cpu on a board meant to support […]
Show full quote

Xeen wrote on 2022-07-23, 10:14:

I always wonder if I can install 386 and 486 CPU at the same time and just use jumpers to decide which to use?

That usually only works with a soldered cpu on a board meant to support

Otherwise

7FCD8A9C-4CEA-43CB-9DCC-D88ACD75CEE1.jpeg

It seems the image is no longer exists, can you re-upload it?

Xeen wrote on 2022-07-24, 01:03:

rmay635703 wrote on 2022-07-23, 15:35:

That usually only works with a soldered cpu on a board meant to support […]
Show full quote

Xeen wrote on 2022-07-23, 10:14:

I always wonder if I can install 386 and 486 CPU at the same time and just use jumpers to decide which to use?

That usually only works with a soldered cpu on a board meant to support

Otherwise

7FCD8A9C-4CEA-43CB-9DCC-D88ACD75CEE1.jpeg

It seems the image is no longer exists, can you re-upload it?

It works fine for me .

darry wrote on 2022-07-24, 02:22:

Xeen wrote on 2022-07-24, 01:03:

rmay635703 wrote on 2022-07-23, 15:35:

That usually only works with a soldered cpu on a board meant to support

Otherwise

7FCD8A9C-4CEA-43CB-9DCC-D88ACD75CEE1.jpeg

It seems the image is no longer exists, can you re-upload it?

It works fine for me .

It is working now 😀

Update: I sold the mobo that was giving me problems (made sure to state "486 only"). Then by pure chance, I bought a mystery beige box, and opened it up to find an Acer VI9 386/486 VLB mobo. It already had a 486DLC installed, so I went ahead with the "NT4 killer test". No crashes, no errors, and memtest passes as well. Definitely doing a build around this one. I guess the other mobo may have had a design flaw (unconnected lines?) in its 386 mode.

Xeen wrote on 2022-07-23, 10:14:

I always wonder if I can install 386 and 486 CPU at the same time and just use jumpers to decide which to use?

Have actually tried this on a FX-3000 386/486 mobo. It wouldn't boot with CPUs in both sockets, but fortunately, no flamethrowers were manufactured.

jakethompson1 wrote on 2022-07-23, 18:50:

kixs wrote on 2022-07-23, 17:23:

Installing NT4 on 386 is pretty optimistic by any standard.

Try adding a FPU for test.

I didn't think NT 4 ran on a 386 at all because of COMPXCHG. But maybe the uniprocessor kernel does?

How do I switch to uniprocessor kernel? Is it an option during setup?

Anyhow, I've already done some testing of NT on 386-class CPUs.

NT 3.51: runs on 386
NT 4.0: no install, no boot on 386. Runs fine on 486DLC
NT 5.0 build 1906: Installs and runs on a 486DLC, but you have to be careful to not trigger CHKDSK, which will freeze at every boot.
2000: With 486DLC, BSOD "KMODE EXCEPTION NOT HANDLED" booting the last phase of setup. Have tried a few motherboards.

FPU made no difference in installation or ability to boot, but in NT5+, it is required for any sound drivers to work.

NScaleTransitModels wrote on 2022-06-29, 17:45:

I finally managed to obtain such a motherboard, so I could try my luck at a 486DLC + VLB build.
It's a UTD 4700 ALL IN ONE, made by Up-To-Date Technologies (never heard of them): https://stason.org/TULARC/pc/motherboards/C/C … ALL-IN-ONE.html

I just won one of these on an auction, and it has some battery damage and a missing chip on the top left of your image, near the ex-battery location and KB connector. Could you do me a favor and take a more detailed pic of that area so I can read the chip and look at the traces? Much thanks!

ahhh, you sold it. there goes my reading comprehension