Here I attach my BIOS dump (hopefully this is ok here). Now, the integrated VGA chipset situation... It's a Cirrus Logic GD5428... I'm familiar with this chipset from a VLB card I have, and I'm very happy with its compatiblity. The bummer on this mobo is that there is only 512KB video memory on board. It's very small for a DX4-class machine. The motherboard doesn't offer any explicit VLB slots, and the riser card that came with it is only 16-bit ISA.. so I'd like to expand this video memory to 1MB or even 2MB if possible.

Looking at the board, I can see an OKI DRAM chip next to the VGA chipset, so I'm assuming this is the 512KB chip. There are pads above it for another chip, but also a long socket that seems to be also connected on the same lines to the OKI.

Questions:

• Would the VGA chip immediately recognize an additional 512KB chip if I solder it in its proper place? Or would that require some bit fiddling in some ROM as well? I can see a bunch of jumpers in the same area, but again, I don't have any documentation as to what they do.
• What DRAM chip could fit in the long socket next to the OKI chip?

Thanks!

Ah yes, ZIP memory sockets. The modules look like these:

(Above modules are not the correct ones)

Thanks for the info on zip memory. This is the first time I see this package form. It would have been convenient to install zips in the slots, but without any manual I guess it's hard to tell what specific type would work there. So for the time being I ordered a couple OKI 512KB chips to solder directly on the board.

148 in SisInfo is the same as I get with an Acer 386DX with a DX4-100 ODP CPU.

~198 is the typical score. My other DX4-100ODPR got this before I put modern caps on it, afterwards it gets ~250. Has 0.1FPS perf difference in 3DBench, no other performance difference anywhere else... SisInfo is a a pure L1 cache x CPU clock score I think.

It's more like a DX3, if such a thing existed 😅
The BIOS has a lot of options for choosing clock rates and delays and wait states. That, and the big number of jumpers on the mobo tells me there could be space to squeeze out some more perf maybe.

It's very similar to the board in my Patriot SL4100 which I found suggestions to be similar to an Ambra system board. Note that it's not made by the IBM PC division, but the IBM microelectronics division, so that makes a difference about where support will be found, which is approximately nowhere.

You should have a full IBM original but recycling i386 stuff Blue Lightning in there, which is like a hyped up 386, added 486 instructions, 16kb cache, kinda similar to the SL chips. Gets about 1.5x IPC of a 386DX or 0.75 IPC of 486... depending... however, for 16 bit stuff, it may go as fast as 1:1 against a 486DX4... no FPU though, hence the Cyrix, but for integer it's about a DX2-66 at 100, DX50 at 66.

These jumper settings seem to match as far as they go...
https://www.praxis8.com/ambra/cobalt.htm

Annoyingly the compiler of that info says elsewhere that a CPU upgrade is "not necessary" so no settings for the 486 socket given. I have not figured mine out fully yet. I seem to have secondary IDE disabled and can't find a ref for the jumper block. Note that the orientation of jumpers is mixed, some up/down, some left/right. So if you find both IDE channels working, then a snapshot of the jumper blocks to compare would be wonderful.

There's my board for reference Re: 3 (+3 more) retro battle stations
and some chatter in that thread. I was working up to a more organised post about it, but then life happened and it got put aside. If you search blue lightning, cobalt and patriot along with my username you might find more tidbits.

edit: oh yah, POST screen here, Re: What retro activity did you get up to today? and up the page and back and forward one or two pages might be more bits and pieces relating to it.

That's definitely a 'proper' Blue Lightning (i.e. IBM's own design, not their later use of Cyrix design sold as Blue Lightning), the presence of the 83D87 Co-Pro (or just its socket) makes that clear enough. Basically this is an LPX version of the Alaris Cougar board. It has the same OPTi (assumedly OPTi 82C499) chipset and SMC I/O controller, just with added CL GD5428 as well

wbahnassi wrote on 2025-06-24, 11:48:

It's more like a DX3, if such a thing existed 😅
The BIOS has a lot of options for choosing clock rates and delays and wait states. That, and the big number of jumpers on the mobo tells me there could be space to squeeze out some more perf maybe.

What BIOS is it? The Cougar had both AMI and MR BIOS. Lots of options sounds like it could be MR...

Mine got third prize, Surepath BIOS with millennium bug, still has speed options though.

Yes this one has a Surepath BIOS as well, and SpeedSys also says it has year 2K bug.

I have the same POST screen as yours Bitwrangler. If you look at my photos, hopefully you can see all the jumpers? But I can take closer pictures on any blocks you need. My machine was indeed using two IDE connectors, the first for HDD and the second for a CD drive, so my jumpers are set to enable both IDE connectors.

[Edit] Just saw your mobo photos, and yes.. it's the exact one I have. Check the photos in my first post for reference on my jumper settings.

BitWrangler wrote on 2025-06-24, 12:20:

These jumper settings seem to match as far as they go...
https://www.praxis8.com/ambra/cobalt.htm

I have 256KB cache and the jumpers match what I see on that page. The VGA enable jumpers though are different than mine, even though mine is enabled as well.
If I read mine correctly, it is:
Closed: [5,7] and [6,8].. everything else is open.

The praxis page suggest [9,10] instead of [6,8]

Yah mine are set like that too... came with a Trident installed in riser, I assume because VGA had a blocked pin, which I drilled out. But I don't think I changed them. So maybe that 6-8 enables ISA video and lets the cards fight it out at boot, first to presence detect monitor, and the other one is true onboard disable.

BitWrangler wrote on 2025-06-24, 15:08:

I assume because VGA had a blocked pin, which I drilled out.

Hehe, that's the first thing I did when I got the machine. Punctured the VGA port with a very sharp screwdriver.

I would have been very happy with the on-board CL VGA chip, except I want it to have 1MB because I like to run CorelDraw on Win3.11 at 800x600 with high colors.
As I said, I did order a couple OKI 512KBs, but they will take a while to arrive (~6 weeks from China). I only found 60ns chips, but the on-board chip is 70ns. Not sure if it's ok to mix and match 60 with 70, but worst case I can replace the existing one with the other 60ns I bought.

My machine came with a 16-bit riser board, so I can't add a VLB VGA replacement card. Otherwise, I don't think a VLB riser would have been needed, as the VGA and IDE controllers are already on VLB, so I only need slots for 16-bit sound cards.

Other than that, I'm a bit torn now between this machine and my proper 486 DX2 build that I already have in a baby AT tower. I did try some software to see if there are any compatibility issues with this Blue Lightning CPU, but the darn thing ate everything I threw at it. Even Terminator 2029 worked without issues, and that game is very touchy about imperfect 386/486 replica CPUs.

So, what is this BL CPU really? A super-boosted 386? Or a week 486 DX4? Any perf/compatibility gotchas to worry about compared to a standard Intel 486 DX2?

It has all the 486 instructions, but using a slow 387 FPU.

Standard 486s have burst writes, and some bus parity which aren't a big deal performance wise.

If you use a standard 486 in the socket 3 it might allow you to use the 486s built-in FPU. My Acer 386DX does this but you need to switch a jumper to tell it a 486 CPU is installed.

If you don't need the FPU, it's probably as fast as it'll get with the BL3 CPU.

wbahnassi wrote on 2025-06-21, 13:33:

The CPU is identified in Norton System Information as 486 SX. I think this isn't quite correct, but then again it's not a 486 DX either.

I wonder what my SIV utility would report it as, I know it correctly reported an IBM 486BLX2 @ 66MHz on 2023-01-07.

The integer speed was 2/3 of my DX2/66 SX955 and the floating about 1/4.

The previous owner had Win98!! installed. The CPU was identified as just Blue Lightning by Windows.. but the OS ran at snail speed and took about a few minutes to fully get to usable desktop. If your tool was DOS based it would have been easier for me to run it on this machine. I'll try to give it a run when I put the previous HDD back, as Win98 (or even Win95) doesn't make much sense for such CPU IMO.

Yeah might not be too bad on an earlier 95 with fast HDD and 8MB+ of RAM but 98 *cringe* Though one trick that can help with 98 and slow systems is to stick another HDD in and swap on that instead of boot drive.

The beginning of my saga was a bit further back in that 3 (+3 more) thread than I thought, jump in at this post and you see the front of my system unit "as unearthed" Re: 3 (+3 more) retro battle stations

Actually your more interesting posts about this motherboard start here Re: 3 (+3 more) retro battle stations
I forgot about them but the other day stumbled upon them and reread them with interest. Also linked them from some other relevant posts.
Do you know if a vlb raiser card can be found for it? Maybe borrow from another model?

It looks kinda like PS/1 or PC series 300 VLB risers might fit, but as wbahnassi says, it's got onboard I/O and the VGA should be good enough with extra RAM, so not anxious to overpay on eBay to find out.