Hi keropi, that's a cute little Baby-AT board you've got! Congrats! 😁

I searched my little mainboard collection, because your board looked so familiar to me.

Well, I have similar board, but it is ALI-based (ALI M1429 A1).

Anyway, the board layout is quite similar. So I thought maybe you can make out jumper settings, etc.
and uploaded a photo of it.

hmmm similar but not quite the same - still there is some interesting silkscreen that I'd love to know what it says since the camera flash made that impossible:

I think the 2 jumpers at the middle-bottom part of your pic left of that Harris IC could have the same function as the ones located at the bottom right corner of my mobo.

It does seem a good board, that's why I want to use it 😀

Okay, I did my best.. Sadly, my camera can't take pictures that close. 🙁
It's an older model, without mechanical zoom and stabilizer.

The room is also quite dim and a lamp doesn't help much.
Without flash or sun shine, it is very difficult to get a proper image.

I even put the board on my scanner, but the result was even more blurry.. 😢

I managed to write down that chart, though.

The text next to the xtal is RESERVE/386DX (jumper, pos. to the right, 1-2)
The text next to the KBC is EXT. BAT (4pin header) and MON/COL (jumper, 3pin, pos. to the right, 1-2)
The jumpers at the front are labeled JP7 (pos. 2-3) and JP6 (pos. 1-2).

I hope this, helps. The numbering of the jumpers on the board is sometimes written in reverse.

thanks for that!
I kinda wish the front jumpers had a description or name ... I guess I'll have to do some testing and see if the weird cpu detection gets fixed

Good Luck! 😀

Jo22 wrote:

Okay, I did my best.. Sadly, my camera can't take pictures that close. :( It's an older model, without mechanical zoom and stabi […]
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Okay, I did my best.. Sadly, my camera can't take pictures that close. 🙁
It's an older model, without mechanical zoom and stabilizer.

The room is also quite dim and a lamp doesn't help much.
Without flash or sun shine, it is very difficult to get a proper image.

Use your flash, but don't take the picture straight from above. Take the picture at a slight angle instead, so the light of the flash doesn't get reflected back into the lens and the tops of the chips stay readable.

Thanks for the tip, yawetaG! 😀

I did some more searching, this time with the BIOS string " 40-04AA-001107-00101111-111192-OP495SLC-8" and found a 486 mobo with a similar one: http://motherboards.mbarron.net/models/486vlb … /opti495slc.htm

The manual has traces of jumpers for 386 motherboards. The bottom right jumpers are for 33 or 40mhz operation. The jumper next to the BIOS are for the external battery (pins 2+3 connected if internal is used) and I assume the one next to it is for color/mono display.
I am still unsure what the one left of the keyboard controller does.
Tried various combos and I could not get the cpu to be recognizes as an AMD 386DX one. Maybe that's how the system sees it as the chipset is a hybrid 386/486 ...

I am attaching the BIOS just in case anyone needs it

Your BIOS is a bit strange to me. For example, it says it is from '87. This doesn't match with its own BIOS message ('85-'92).
Besides, these Cyrix chips weren't released until '93/'94. So how can a BIOS from '92(?) know about them already ?
Ok, maybe it has got a table about prototypes already.. But still, this doesn't feel right.
Perhaps something is wrong with that BIOS, it got replaced or it is just confused because of some jumper setting.
I'd remove that battery and wait until the CMOS is cleared.

Here's a list of older processors and their release dates:
http://files.mpoli.fi/unpacked/software/texts … ip/chipsfaq.txt

Edit: I found another BIOS for OPTI 82C495SLC. Its description also mentions 386DX40. File name is 3opm008.zip.
If you wish, I could write it to an EPROM chip for you. 😀

I doubt the bios was replaced, the same sticker is on the keyboard controller.
The battery was dead/leaking and replaced, it spent more than 48hrs without a battery so the CMOS was cleared. Still the CPU is reported as a Cyrix.

The sticker just tells you about the core code. So it is based on the 386DX ISA BIOS core from AMI that is (c) 1987. All the tables and chipset options are as of 1992/11/11. Usually this date is taken as the BIOS date as the core BIOS is used on a lot of different boards (with different tables depending on chipset).
The Cyrix M6 was released as Cyrix 486DX in May 1993. So it is likely that they already had preliminary support in Nov 1992.

Hello again, I've searched the web for a manual and found this page:
http://motherboards.mbarron.net/models/486vlb … /opti495slc.htm

I has got a manual for 82c495SLC; keropi's chipset.
It's not the same board, though, (more like totally different) but perhaps there are some details explained.
Like meaning of certain jumpers, BIOS information, chipset specifications, etc.

elianda wrote:

The sticker just tells you about the core code. So it is based on the 386DX ISA BIOS core from AMI that is (c) 1987. All the tables and chipset options are as of 1992/11/11. Usually this date is taken as the BIOS date as the core BIOS is used on a lot of different boards (with different tables depending on chipset).
The Cyrix M6 was released as Cyrix 486DX in May 1993. So it is likely that they already had preliminary support in Nov 1992.

Thank you, elianda! 😀
But there's something I want to ask-I've seen some other chips with actual date codes or version numbers.
Was this core-version numbering scheme mainly done with socalled "modular BIOSes",
or also with non-modular flavors (if they existed). Just curious, because the Award models say "Award Modular BIOS".

^ yeah found the same page a couple of posts above. The manual does state some stuff for 386DX systems but nothing that matches 100% - only guesswork. The only jumper I have no idea what it does is the one next to the keyboard controller. I am waiting atm for a replacement battery as the mobo without one does report strange cpu models, like a 16mhz 80386 so maybe there's something there.

Oh. I see. 😊
Haven't noticed they're the same, haha.. 😅
Seems the BIOS I have found has the same date code as yours..
Guess I have to find another one. If there is any..

Maybe there is another newer amibios I can test, if anyone has any suggestion please do tell 😀

It occured to me, Cyrix M6 is a 486 cpu, right? If yes then it's just weird having a 386 getting detected as 486... haven't located a newer BIOS to test yet - no idea if it's even possible to do so.
Ran some benchmarks too , the board is slightly faster than my BIOTEQ-based one:

Finally decided to test the mobo before I move it to my 386DX build.

This is ~21hrs of testing with 8MB 60ns RAM (sadly 3 kinds mixed) and every memory option in bios set to 0WS and fastest timing available. I think it's all good 😀

edit:
had another look on the manual about an Opti495SLC Jo22 and I found , on the very last pages they have the correct BIOS options for various 486 and 386 cpus, and the one for the 386DX/40 is:

It is the auto-config function that made the difference, once I disabled it I get this on boot:

I also had the "AT BUS Clock Selection" at the default that BIOS loaded: CLK1/6 , I wonder what difference the correct 1/5 value makes (yes it does, in wolf3D benchmark from 23,9fps I get now 24,3 🤣 🤣 🤣 )

I just bought an earlier revision of this same motherboard - the only reference I can find to it on the web is really just your thread, but also this post on google groups: old newsgroup post

Mine came with 16MB of ram fitted by the seller, and until I set up DOS correctly, it wasn't working too well? But now it's behaving very nicely with the games I wanted to try with it. Here's what I've worked out from my testing of it so far:

1JP1 - CPU frequency jumper 1
2default state is connected
3pin1=ground/vss
4pin2=pin5 of pll, s1 on pll truthtable
5
6
7JP2 - CPU frequency jumper 2 
8default state is connected
9pin1=ground/vss
10pin2=pin4 of pll, s0 on pll truthtable
11
12
13JP3 - Display mode
14default state is connected
15pin1=ground
16pin2=pin33 of 8042 (p16), CGA (Colour/VGA) display or MDA (Monochrome) display switch. 
17
18
19J4 - RTC battery
20default=2&3 connected
21pin1=I guess battery +
22pin2-3= connect to use onboard RTC battery
23pin4=ground
24
25JP4 - Battery type
26Positions:
271-2 = lithium cell (not rechargeable)
282-3 = ni-cd
29default state with varta battery connected was 1-2 for some reason, which means it doesn't charge
30
31pin1=diode under EEPROM
32pin2=pin3 of J4 > positive terminal on battery
33pin3=some resistor under EEPROM
34
35JP5 - unknown, connected via solder. Connects to Opti F82C206Q
36
37JP6 - unknown, connected via solder. Looks like it has something to do with ISA bus, goes into LS245 chip next to it
38
39JP7 - Something to do with cache
40unable to change, board has max cache & jumper wire is soldered between pins 1&2
41
42JP8 - Something to do with cache
43unable to change, board has max cache & jumper wire is soldered between pins 1&2
44
45IMI SC425 is the PLL chip
46s0=ground(low/0)
47s1=ground(low/0)
48s2=open(high/1)
49s3=ground(low/0)
50That should result in 80mhz on MCLK2 and 40MHz on MCLK1

Beyond getting the RTC battery working with a lithium coin cell, there's not really anything else to configure - mine has the same incorrect ISA divider of CPU/6

I think this is the earlier version of the board because the BIOS string has a version difference:
40-0200-001107-00101111-111192-OP495SLC-8
The battery jumper is in a different place and there are a couple of other minor differences, but otherwise it's just about the same. For some reason, I can set 0 WS on everything and tight timings and it's still reliable ,but the cache chips are 25ns??
Also, does the turbo button do anything on your board? Mine doesn't seem to react to turning turbo on/off

Here's a backup from its BIOS if you'd like to try it, but I expect it won't make any significant difference.

And in today's search, I found the motherboard manual! except I don't want to pay for it. It looks like the motherboard is called the "Opti 495SLC Pure": https://www.ebay.com/itm/OPTI-495SLC-PURE-386 … et/323871827730

Still no information on bios updates, manufacturer, or the jumper settings though 😀