BTW does nayone know what's the red round SMD on the top left corner? Looks like corrosion had its way with it.

BIOS:
Top string:

386-BIOS (C)1989 American Megatrends Inc

Bottom string:

(C) American Megatrends Inc.,
DAMI-3601-043089-K8

Yes please reupload them with a higher res ! I'd like to add it here http://www.win3x.org/uh19/motherboard/show/3420 😀

(now the direct light from your camera doesn't help). Can you image these ROMs files too ?

iirc the red thing is some kind of adjustable capacitor

Wow, four BIOS chips!
On 286 boards (16-bit bus), it's common to have two BIOS chips - ODD and EVEN.
386 boards (32-bit bus), however, usually avoid having four chips, but this one is different...

Grzyb wrote on 2020-10-03, 21:17:

Wow, four BIOS chips!
On 286 boards (16-bit bus), it's common to have two BIOS chips - ODD and EVEN.
386 boards (32-bit bus), however, usually avoid having four chips, but this one is different...

Hi!
Can you expand on this subject? I know nothing about it.

Deksor wrote on 2020-10-03, 20:34:

Yes please reupload them with a higher res ! I'd like to add it here http://www.win3x.org/uh19/motherboard/show/3420 😀

Ok 😀

Deksor wrote on 2020-10-03, 20:34:

(now the direct light from your camera doesn't help). Can you image these ROMs files too ?

Yeah, I forgot the flash on and it was night, not the best combination.

You have to guide me to get those ROMs images, I wouldn't know how to do that.

Deksor wrote on 2020-10-03, 20:34:

iirc the red thing is some kind of adjustable capacitor

Looks like it's failing and I'd like to get a new one.

The oscillator (crystal) is a 66.6mhz (top right corner).
Does this limit the cpu speed to 33mhz? It's soldered to the board but I could remove it and solder a socket to put an 80mhz oscillator.

But that would modify ISA speed (otherwise it would have been socketed and not soldered?) and maybe the bios doesn't have the right divider?

For the socillator, it depends of your mobo and chipset. Some are capable of taking 40MHz natively, others will take the 7MHz overclock, and some won't I think.

For the ROMs, you either need a programmer like the TL866 (best solution and you don't have to turn on the motherboard) or this https://cdn.discordapp.com/attachments/282620 … 7084/GETROM.ZIP (which is great but more limited)

Deksor wrote on 2020-10-04, 10:35:

For the socillator, it depends of your mobo and chipset. Some are capable of taking 40MHz natively, others will take the 7MHz overclock, and some won't I think.

For the ROMs, you either need a programmer like the TL866 (best solution and you don't have to turn on the motherboard) or this https://cdn.discordapp.com/attachments/282620 … 7084/GETROM.ZIP (which is great but more limited)

Thanks for the reply.

I'll do my best to get those ROMs!

Stuff (old 2019)

Nexxen wrote on 2020-10-04, 09:39:

Grzyb wrote on 2020-10-03, 21:17:

Wow, four BIOS chips!
On 286 boards (16-bit bus), it's common to have two BIOS chips - ODD and EVEN.
386 boards (32-bit bus), however, usually avoid having four chips, but this one is different...

Hi!
Can you expand on this subject? I know nothing about it.

Various processors have various data bus width:
8088 - 8-bit
8086, 286, 386SX - 16-bit
386DX, 486 - 32-bit

and the attached memory (RAM or ROM) must match.
Eg. 30-pin SIMM modules are 8-bit-wide, therefore one such module isn't enough for a 286 or 386SX - you need 2 or 4 of them.
For 386DX or 486 boards, you need 4 or 8.

Same story with ROM - 286 boards usually come with two 8-bit-wide chips.
386DX/486 would need four, and that board of yours is an example that some early boards indeed have four.
Later boards, however, do some multiplexing or similar technique - as a result, they only need one ROM chip for BIOS.

Nexxen wrote on 2020-10-04, 09:47:

The oscillator (crystal) is a 66.6mhz (top right corner).
Does this limit the cpu speed to 33mhz? It's soldered to the board but I could remove it and solder a socket to put an 80mhz oscillator.

But that would modify ISA speed (otherwise it would have been socketed and not soldered?) and maybe the bios doesn't have the right divider?

Why bother?
386DX-40 boards are plentiful.
That Laser 386M board, however, is a not-so-common example of much earlier 386 technology, it's beautiful as it is.
I can see chips from 1989/1990 - long before 40 MHz 386s were released.
In fact, Intel has never released 386 chips faster than 33 MHz, the 40 MHz ones were from AMD only.

Grzyb wrote on 2020-10-04, 16:32:

Why bother? 386DX-40 boards are plentiful. That Laser 386M board, however, is a not-so-common example of much earlier 386 techno […]
Show full quote

Nexxen wrote on 2020-10-04, 09:47:

The oscillator (crystal) is a 66.6mhz (top right corner).
Does this limit the cpu speed to 33mhz? It's soldered to the board but I could remove it and solder a socket to put an 80mhz oscillator.

But that would modify ISA speed (otherwise it would have been socketed and not soldered?) and maybe the bios doesn't have the right divider?

Why bother?
386DX-40 boards are plentiful.
That Laser 386M board, however, is a not-so-common example of much earlier 386 technology, it's beautiful as it is.
I can see chips from 1989/1990 - long before 40 MHz 386s were released.
In fact, Intel has never released 386 chips faster than 33 MHz, the 40 MHz ones were from AMD only.

In the end desoldering may damage the board so I'm keeping it like that.
In theory if I put a 80mhz oscillator would it work (conceding that bios and bus are ok with it)?

Yes it would

On theboard there are 8x these chips:

inmos 8932-b
ims1624p-30

Are they cache? I couldn't find any info on them.

Yes, IMS 1624 = 16K x 4 SRAM
So there's total of 64 KB cache.

Thanks Grzyb!

Edit: system memory is (RAM - 640KB); cache is 64kb onboard.

New and better pictures of the board have been uploaded some time ago, feel free to use them. However the board doesn't exactly match the diagram already uploaded.

Atrom and xtrom.

I did both and here they are:

Thank you very much ! Everything is on the page now 😀

Deksor wrote on 2020-10-10, 13:01:

Thank you very much ! Everything is on the page now 😀

Could you get the 4 roms correctly? If I wanted a copy of these 4 roms what kind of chips should I order?
I'm thinking on buying a "chip" programmer.

As long as I have the board out ask for stuff.