Been searching the net for any motherboard with this chipset, the majority as expected are 386, with normally 8 simm slots and all the jumper settings say a maximum of 8mb, so it looks like 4mb is the maximum this motherboard can take, unless I populate the dip packages maybe, so a total of 5mb maybe?

simon_e_hall wrote on 2022-06-13, 16:55:

weedeewee wrote on 2022-06-13, 16:43:

Are any of the 4MB simms you tried 9 chips ?

like this "4 MB Simm 30-pin 80 ns 9-Chip 4Mx9 Parity 'Chips: 9 x Siemens HYB514100BJ-80'"

Unfortunately they all are! I thought that could be part of the issue.

9 chip SIMMs are always more compatible than their 3 chip counterparts

Might see if I have any 1mb 9 chip SIMMs anyway and give them a try, again majority in my collection are 4mb 9 chip or 1mb/ 256k 3 chip

Wonder what is the purpose of the second crystal oscillator since is it not present on the mobo here.
The more interesting thing is the placeholder for the full can oscillator next to the FPU.
Wanted to see if it can provide alternative frequency to the already very fast FPU circuitry on this PCB.

Quite a few late 286 mobos are based on 386 chipsets and handle up to 16Mb of RAM.
Most of them take easily any kind of 512Kb/1Mb/4Mb modules.
Not the most useful thing for a 286 system but more RAM is always better.

Some late ISA VGA cards don't work well or at all on some XT/286 motherboards.
For example CL GD-5434 won't light-up on most XT/286 mobos.

Been doing some testing, JP9 is I believe linked to the 2nd crystal.

pins 2 & 3 CPU 29.73, FPU 28.38 and Video 6342.18 in landmark
pins 1 & 2 CPU 29.59, FPU 24.63 and Video 5041.23

Not much of a change for the CPU/ 287 but a big hit for the video.

leaving it with no jumper on freezes the system.

Same thing happens if you change the jumper (JP1) next to the 287, so would assess that jumper is somehow connected to the FPU to allow it to run seperate to the CPU.

So another area to experiment on, when I get round to ordering a socket for the crystal, will get a few and put one there as well.

Also on your motherboard JP2 also next to the 287 has a jumper to short, whereas mine is straight out shorted, any idea what that might have done, wait state for the FPU possibly?

Had a play and populated the socketed RAM, also there is a horrible option in the BIOS '384KB Memory Relocation' which makes the upper memory extended if enabled, which really confused any upper memory manager I tried to install. The result 1mb base, 4mb extended and with the LoTech 2mb EMS, so not too bad. Might try and change the simm to 1mb 9 chip just to see if it can actually take them (also think they look cooler!).

Odd, this info would indicate your chipset version supports 4M , HT18/C . though, perhaps I'm reading it wrong.

http://66.113.161.23/~mR_Slug/chipset/c ... ,8624#8650

Yes. Up to 16Mb on this board.

Looked at my notes.
J1 - in position 1-2 FPU uses the base frequency. in position 2-3 FPU uses the crystal oscillator next to it. if the oscillator is not present - no FPU.
J2 - no visible change in perf or other parameters of the system
J9 - looks like it switches between the first and second crystal oscillator - a bit odd, but i can see how this can be a product feature.

Will slap a socket for oscillator next to the FPU and see what comes out of it.

These Headland HT## chipsets offer nice control over FPU.
Because of that they usually trump anything else 286 in that department.
If this mobo can feed alternative frequency to the FPU that is not based on the base clock - that can be epic.
I had this on my to-do list to verify but forgot about it.
Remembered after checking the notes.

For the sake of the broader conversation - i don't find anything charming in early clumsy 286 (and 386 in that count) PCBs.
A bit of nostalgia factor that gets quickly erased when the whole system starts acting up and you cannot get it an inch above its 12MHz specification.
But at the same time - the very late 286/386 boards get a bit boring - to set them up is basically turning them on and job is done.
While the system is stable and such - it is too narrow and cost trimmed which takes most of the fun away.
Neither extreme is good really.

simon_e_hall wrote on 2022-06-13, 15:05:

Okay, so what I thought was going to be a simple build has thrown some curve balls at me. […]
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Okay, so what I thought was going to be a simple build has thrown some curve balls at me.

1) ET4000 with no modifications acchives 6.8fps in 3D Bench v1.0, so thought that I would try some other cards to see if I can get a litter more performance and well, it hates my 'modern' ISA cards, system will not post with either my Diamond SpeedStar 64 or S3 928 cards, which is fine except I have a lot of noise on the ET4000 which I suspect is the RAMDAC.

System gives three rapid beeps then eight slow/long beeps with the 'modern' cards in, so I as remember it is telling me it cannot see a display adapter but need to check that, if it is that I do remember many years ago reading that some motherboards had issues with the newer vga cards as they did not use a certain signal, but again need to research that.

2) Tried every on board BIOS option with the Promise EIDE card but it will not detect my 512MB CF Card, but disable it and use the system BIOS and it works perfectly, so no large hard drive support (at the moment).

3) As I expected no EMS options in the BIOS so installed the EMS board, but the Upper memory has region E000-EFFF as read only, so lost a good wad of upper memory and cannot see any BIOS option to free it up.

4) Sound cards, wow reading the comments above I can see there are many thoughts, I would love an MT-32 but they are so expensive it is stupid, but due to the missing two ISA slots being a small board, like you all said it needs MIDI and digital sounds, I totally agree. Especially as I want to play Day of the Tentacle with both music and voice, especially for the opening scenes!

SB Pro 2.0: Causes system not to post, board works fine in other systems so slightly stumped there.
SB16: Digital sound is distorted/ or clipped and MIDI does not work (have a MIDI daughter board installed)
Terratec Maestro: Digital sound works sometimes and MIDI sometimes work (used same MIDI daughter board as on SB16).
PAS16: same issues as the Terratec Maestro
8-bit TopTek Goldern sound card: Works brilliantly but no MIDI without an external box (have an SC-55, it is no MT-32 but works).

However, as of today have a generic ALS100+ card in there with a MIDI daughter board and have finally both digital sound and MIDI working. The only game that won't work with the MIDI is Wing Commander 1, but remember that was always picky with MIDI and that does not bother me too much.

5) Tried to install 16mb of RAM but it hates every 4mb SIMM I have, not to concerned about that though, 4mb should be plenty for the time being.

So next plan:

1) Is to either find another ET4000 card or replace the RAMDAC in the one I have, might even try and find an ET4000 W32.
2) Install the correct crystal for a 25Mhz CPU.
3) Burn and install a MR. Bios chip, when I finally get round to getting a new programmer.

4) Had not considered overclocking but now someone has mentioned it, might try it in the future.

I wonder if the VGA BIOSes in the newer video cards might contain 386 instructions. That would certainly cause a failure at bootup.
How big of a drive do you actually want to use on this system? 512MB seems pretty roomy to me for a 286. Is the issue that the system BIOS doesn't allow setting custom hard drive parameters? It's likely you could hack the BIOS to change one of the hardcoded, useless 20MB hard drive types in it to be 1024/16/63 so you can max out the 528MB capacity without any overlay software or custom BIOS. You could also try XT-IDE BIOS.

Not sure if there's a DOS driver specific to that chipset to provide EMS. It could also be informative to find its datasheet.

maxtherabbit wrote on 2022-06-13, 15:54:

Just for giggles try the newer video cards without the EIDE controller installed

Never heard of any 286 board that supports 4MB SIMMs FWIW

Anonymous Coward wrote on 2022-06-13, 16:31:

There were 286 boards made that used chipsets for 386SX that support 4MB SIMMs. They all would have been 90s vintage.

You guys might like this that I posted recently--286 board with 72-pin SIMM support (once I soldered a socket onto the vacant header). Perhaps it would have gathered more attention with a picture. JCS286/SCAT (82C235) Motherboard

simon_e_hall wrote on 2022-06-13, 18:46:

Had a play and populated the socketed RAM, also there is a horrible option in the BIOS '384KB Memory Relocation' which makes the upper memory extended if enabled, which really confused any upper memory manager I tried to install. The result 1mb base, 4mb extended and with the LoTech 2mb EMS, so not too bad. Might try and change the simm to 1mb 9 chip just to see if it can actually take them (also think they look cooler!).

Enabling that relocation setting might also disable system BIOS shadowing on your board. And because your BIOS appears to be a single chip and not odd/even, it's likely that BIOS accesses are much slower than RAM, so you really want shadowing.

Saw the listing the other day but passed on it because of the SCAT chipset. Clunky stuff.
I have seen 386 motherboards with 72-pin SIMM slots too but such memory slot on 286 is unusual for sure.
Too bad SCAT is incapable to utilize the possibilities this kind of RAM brings for overclocking.

jakethompson1 wrote on 2022-06-14, 01:48:

simon_e_hall wrote on 2022-06-13, 18:46:

Had a play and populated the socketed RAM, also there is a horrible option in the BIOS '384KB Memory Relocation' which makes the upper memory extended if enabled, which really confused any upper memory manager I tried to install. The result 1mb base, 4mb extended and with the LoTech 2mb EMS, so not too bad. Might try and change the simm to 1mb 9 chip just to see if it can actually take them (also think they look cooler!).

Enabling that relocation setting might also disable system BIOS shadowing on your board. And because your BIOS appears to be a single chip and not odd/even, it's likely that BIOS accesses are much slower than RAM, so you really want shadowing.

Some interesting points, in answer to your question, the larger hard drive capacities are a nice to have idea and if I did do it probably only up to 2gb more in that I have more 2gb CF cards than 512mb which I am using at the moment.

Considered XT-IDE, that is why I have put the network card in as a possible future expansion/ experiment.

The relocation setting in the BIOS is enabled by default which seems a odd setting and to use the memory as you would expect it has to be disabled (which is what I have it set on now). You might be right regarding shadowing, tried to enable it before I started really seeing what this board can do and well, nothing would not work, because maybe the BIOS default is enabled, so another experiment to try out...

pshipkov wrote on 2022-06-13, 22:23:

Yes. Up to 16Mb on this board. […]
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Yes. Up to 16Mb on this board.

Looked at my notes.
J1 - in position 1-2 FPU uses the base frequency. in position 2-3 FPU uses the crystal oscillator next to it. if the oscillator is not present - no FPU.
J2 - no visible change in perf or other parameters of the system
J9 - looks like it switches between the first and second crystal oscillator - a bit odd, but i can see how this can be a product feature.

Will slap a socket for oscillator next to the FPU and see what comes out of it.

These Headland HT## chipsets offer nice control over FPU.
Because of that they usually trump anything else 286 in that department.
If this mobo can feed alternative frequency to the FPU that is not based on the base clock - that can be epic.
I had this on my to-do list to verify but forgot about it.
Remembered after checking the notes.

Did you ever get 4mb modules to work? None of those in my collection will play ball.

Nice we have come to similar conclusions on the jumpers. In your notes did you have further details on the jumpers that control the RAM? I was playing with them last night to map them out and gave up, shorting them all on pins 2 and 3 seems to enable everything, but then had similar results in other configurations.

My favorite 286 boards are the ibm type 1-4. They’re really basic, but strangely fun.

This thread has sealed the deal. I will replace my 386SX-25 system with a 286-16 using this mainboard 😀

appiah4 wrote on 2022-06-14, 10:45:

This thread has sealed the deal. I will replace my 386SX-25 system with a 286-16 using this mainboard 😀

Huh? A downgrade?

Isn't DOOM like, really unplayable on 286?

kitten.may.cry wrote on 2022-06-14, 10:56:

appiah4 wrote on 2022-06-14, 10:45:

This thread has sealed the deal. I will replace my 386SX-25 system with a 286-16 using this mainboard 😀

Huh? A downgrade?

Isn't DOOM like, really unplayable on 286?

It is. But I can play Doom on my alarm clock and refrigerator so I'm OK with that.

@simon_e_hall
The one here works fine with 4x4Mb RAM. Not picky at all.

This thread is turning well with now appiah4 stepping down on 286 path with very mediocre board that should at least partially satisfy Anonymous Coward's lust for this kind of stuff.
Which makes me wonder if the different HL chipset version 101/12/16/18 are pin compatible. I should search online for datasheets first before asking the question here, but if somebody knows right away ...

Amazing to see the interest this has caused, thought it would be a rather low-key build. Anyway, got a new graphics card for the build, no issues and system POSTs, it is not a large boost but gone from 6.8fps of the old ET4000 to 7fps with this card, no tweaks, if I put the wait state on it drops back to 6.8fps.
Also it does not cause have fit inducing flickers in certain text modes, also no noise and VESA 1.2 and the ability to go to 2mb possibly.

EDIT: Well tried making this a 2mb board (would have tried a while ago but got distracted playing Wing Commander), installed the 256k / 4 bit modules, and well...

It still detects it as a 1mb card, so I swapped the RAM with what is on the motherboard to see if it was defective modules but no all works, so my modules are good the graphics card just cannot see the RAM. Seems a bit stupid of a company to put the sockets on a board if they don't work, also notice the capacitors next to the sockets are missing as well, seems odd.