VOGONS


What are these different chips? (AST 486)

Topic actions

First post, by ralphmaif

User metadata
Rank Newbie
Rank
Newbie

Picked up a very clean AST Advantage Adventure 343 (i486dx2 50MHz) last week. My goal is to make this an ultimate 486 platform build (CF card drive, overdrive CPU, full memory, etc.).

I did a tear down to figure out upgrade options since it came with no manuals/disks and haven't been able to source them yet. It's got an ATI Mach32 with 1MB of RAM built-in and 8KB of onboard cache. Whoever bought it (and never used it) added a 16MB EDO stick to the base 8MB config, but it will apparently max out at 64MB.

There also are 3 different banks of different chips: 8x DIP28 and a pair of 2x DIP16 in the upper left of the photo; a pair to the lower right of the CPU of what look like they could be... Boot ROMs? Idk.

Anyway, anybody recognize these or have an idea of what I should be looking for?

The attachment PXL_20260322_185212430-1.jpg is no longer available
The attachment PXL_20260323_144020434.jpg is no longer available

Reply 1 of 35, by myne

User metadata
Rank l33t
Rank
l33t

Top left looks like cache chip sockets
Bottom right below the VRAM looks like VRAM expansion sockets.

I built:
Convert old ASUS ASC boardviews to KICAD PCB!
Re: A comprehensive guide to install and play MechWarrior 2 on new versions on Windows.
Dos+Windows 3.11+tcp+vbe_svga auto-install iso template
Script to backup Win9x\ME drivers from a working install
Re: The thing no one asked for: KICAD 440bx reference schematic

Reply 2 of 35, by ralphmaif

User metadata
Rank Newbie
Rank
Newbie

Nice, that was fast. Thank you!

I was only coming back so quick to correct that there is no cache currently (instead of the 8kb I stated, whoops).

What's the deal with the cache banks being 2 different specs?

Reply 3 of 35, by jakethompson1

User metadata
Rank l33t
Rank
l33t

Checking a few similar boards on theretroweb, it looks like your board uses unusual, 32-pin 32Kx9 SRAM for the tag, rather than using a x8 chip for tag and x1 chip for dirty, or 7+1 tag mode to use a x8 chip for both, or always-dirty.

Reply 4 of 35, by rasz_pl

User metadata
Rank l33t
Rank
l33t
ralphmaif wrote on 2026-03-24, 02:34:

Picked up a very clean AST Advantage Adventure 343 (i486dx2 50MHz)

Nice. Looks like AST Advantage Adventure 343 is not in theretroweb database. Looking at just 486 AST variants its ~30 entirely different motherboard designs. WTF were they thinking.

ralphmaif wrote on 2026-03-24, 02:34:

My goal is to make this an ultimate 486 platform build

run https://advsys.net/ken/util/vidspeed.exe to check if that Mach32 is on ISA or VLB/System bus. If its ISA the system will not be all that Ultimate.

ralphmaif wrote on 2026-03-24, 02:34:

Whoever bought it (and never used it) added a 16MB EDO stick to the base 8MB config

486 chipsets generally didnt support EDO, if its really edo you might expect randomly crashing system when computer starts using that ram. Its possible its mapped above 8MB now so running just dos works fine, but loading windows or bigger game will show it. Not that you really need that much ram. There werent really any games that would use more than ~12MB of ram and still run acceptably on 486. Win95 will also be a challenge for dx2.

Cache upgrade might be exciting.

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/440BX Reference Design adapted to Kicad

Reply 6 of 35, by rasz_pl

User metadata
Rank l33t
Rank
l33t
PC Hoarder Patrol wrote on 2026-03-24, 06:12:

pictured p/n looks like 202528, so related to this one possibly... https://theretroweb.com/motherboards/s/ast-br … o-mt-202528-xxx

Nice find. Cant find E5 E6 E14 and video memory banks are labeled wrong. E14 supposed to be "Factory configured - do not alter", might mean its a slightly later revision of same design.

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/440BX Reference Design adapted to Kicad

Reply 7 of 35, by ralphmaif

User metadata
Rank Newbie
Rank
Newbie
jakethompson1 wrote on 2026-03-24, 04:33:

Checking a few similar boards on theretroweb, it looks like your board uses unusual, 32-pin 32Kx9 SRAM for the tag, rather than using a x8 chip for tag and x1 chip for dirty, or 7+1 tag mode to use a x8 chip for both, or always-dirty.

Right, I have to admit I've not seen this mix before.

Reply 8 of 35, by ralphmaif

User metadata
Rank Newbie
Rank
Newbie
rasz_pl wrote on 2026-03-24, 05:45:
Nice. Looks like AST Advantage Adventure 343 is not in theretroweb database. Looking at just 486 AST variants its ~30 entirely d […]
Show full quote
ralphmaif wrote on 2026-03-24, 02:34:

Picked up a very clean AST Advantage Adventure 343 (i486dx2 50MHz)

Nice. Looks like AST Advantage Adventure 343 is not in theretroweb database. Looking at just 486 AST variants its ~30 entirely different motherboard designs. WTF were they thinking.

ralphmaif wrote on 2026-03-24, 02:34:

My goal is to make this an ultimate 486 platform build

run https://advsys.net/ken/util/vidspeed.exe to check if that Mach32 is on ISA or VLB/System bus. If its ISA the system will not be all that Ultimate.

ralphmaif wrote on 2026-03-24, 02:34:

Whoever bought it (and never used it) added a 16MB EDO stick to the base 8MB config

486 chipsets generally didnt support EDO, if its really edo you might expect randomly crashing system when computer starts using that ram. Its possible its mapped above 8MB now so running just dos works fine, but loading windows or bigger game will show it. Not that you really need that much ram. There werent really any games that would use more than ~12MB of ram and still run acceptably on 486. Win95 will also be a challenge for dx2.

Cache upgrade might be exciting.

Yeah, I noticed it's not in their database, so I'll be submitting it to theretroweb sometime this week. I'd be curious how many of these are still lurking about out there. I had an AST 486 DX33 when I was in high school in the early 90s, and it was one of my favorite PCs as I remember it not only coming pretty well loaded for the time (4MB RAM, ~250MB HD, dual-speed CD, etc.), but was pretty easily upgradable. It was very similar aesthetically to this 343, but I don't remember it having the hard disk mounted on a removable shroud like this one came.

Vidspeed seems to only run on Pentium or higher CPUs. Looks like the author has some other utilities I can try to test it out...

Thanks for the heads up on the memory spec!

Reply 9 of 35, by ralphmaif

User metadata
Rank Newbie
Rank
Newbie
PC Hoarder Patrol wrote on 2026-03-24, 06:12:

pictured p/n looks like 202528, so related to this one possibly... https://theretroweb.com/motherboards/s/ast-br … o-mt-202528-xxx

Right, as rasz indicated, looks very similar with some differences. Hopefully the jumper manual in that profile applies at least, as that will help with some configurations. Thanks for posting!

Reply 10 of 35, by dionb

User metadata
Rank l33t++
Rank
l33t++
myne wrote on 2026-03-24, 03:04:

Top left looks like cache chip sockets
Bottom right below the VRAM looks like VRAM expansion sockets.

Not quite, despite the Mach32 supporting VRAM too, on this board DRAM is used. See download/file.php?id=179522

Reply 11 of 35, by ralphmaif

User metadata
Rank Newbie
Rank
Newbie
dionb wrote on 2026-03-24, 18:15:
myne wrote on 2026-03-24, 03:04:

Top left looks like cache chip sockets
Bottom right below the VRAM looks like VRAM expansion sockets.

Not quite, despite the Mach32 supporting VRAM too, on this board DRAM is used. See download/file.php?id=179522

^that's what I ended up picking up from eBay, only Samsung not Hitachi.

Reply 12 of 35, by ralphmaif

User metadata
Rank Newbie
Rank
Newbie
ralphmaif wrote on 2026-03-24, 15:04:
PC Hoarder Patrol wrote on 2026-03-24, 06:12:

pictured p/n looks like 202528, so related to this one possibly... https://theretroweb.com/motherboards/s/ast-br … o-mt-202528-xxx

Right, as rasz indicated, looks very similar with some differences. Hopefully the jumper manual in that profile applies at least, as that will help with some configurations. Thanks for posting!

This is actually bang on -- the part number is on the photo I posted (no trailing characters, though).

Reply 13 of 35, by myne

User metadata
Rank l33t
Rank
l33t
dionb wrote on 2026-03-24, 18:15:
myne wrote on 2026-03-24, 03:04:

Top left looks like cache chip sockets
Bottom right below the VRAM looks like VRAM expansion sockets.

Not quite, despite the Mach32 supporting VRAM too, on this board DRAM is used. See download/file.php?id=179522

The v means video.
There's no such thing as vram as a product.

I built:
Convert old ASUS ASC boardviews to KICAD PCB!
Re: A comprehensive guide to install and play MechWarrior 2 on new versions on Windows.
Dos+Windows 3.11+tcp+vbe_svga auto-install iso template
Script to backup Win9x\ME drivers from a working install
Re: The thing no one asked for: KICAD 440bx reference schematic

Reply 14 of 35, by rasz_pl

User metadata
Rank l33t
Rank
l33t
ralphmaif wrote on 2026-03-24, 14:56:

Vidspeed seems to only run on Pentium or higher CPUs. Looks like the author has some other utilities I can try to test it out...

vidspeed should even run on 386. Here few benchmarks showing what to expect on DX50 and dx2/66 with diffeent graphic chips https://brassicgamer.blogspot.com/2023/04/the … 6.html#vidspeed

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/440BX Reference Design adapted to Kicad

Reply 15 of 35, by akimmet

User metadata
Rank Member
Rank
Member
myne wrote on Yesterday, 00:50:
dionb wrote on 2026-03-24, 18:15:
myne wrote on 2026-03-24, 03:04:

Top left looks like cache chip sockets
Bottom right below the VRAM looks like VRAM expansion sockets.

Not quite, despite the Mach32 supporting VRAM too, on this board DRAM is used. See download/file.php?id=179522

The v means video.
There's no such thing as vram as a product.

There is indeed such a thing as VRAM, and there are Mach32 variants that use it.
VRAM was once a common name for dual-ported DRAM.
Eventually VRAM became a generic term for any type of video RAM.

https://en.wikipedia.org/wiki/Dual-ported_video_RAM

Reply 16 of 35, by ralphmaif

User metadata
Rank Newbie
Rank
Newbie
rasz_pl wrote on Yesterday, 03:16:
ralphmaif wrote on 2026-03-24, 14:56:

Vidspeed seems to only run on Pentium or higher CPUs. Looks like the author has some other utilities I can try to test it out...

vidspeed should even run on 386. Here few benchmarks showing what to expect on DX50 and dx2/66 with diffeent graphic chips https://brassicgamer.blogspot.com/2023/04/the … 6.html#vidspeed

Hmm...is there another version of it out there? It wouldn't even run until I paired it with dos4gw, and then it just quit, demanding I have a pentium. The system came loaded with DOS 6.21 and Windows 3.1.

I do have a POPD5V83 I could pull from a Compaq Prolinea MT 66, but I'd rather avoid that for now...even though the article you posted is absolutely fascinating and has me wanting to try all sorts of hardware combos mixes 'n matches between the two.

Reply 17 of 35, by Babasha

User metadata
Rank Oldbie
Rank
Oldbie

ATI MACH 32 on ISA bus here. Not good not bad anyway.

Need help? Begin with photo and model of your hardware 😉

Reply 18 of 35, by rasz_pl

User metadata
Rank l33t
Rank
l33t

Im sorry, I linked Ken Silverman's page expecting him hosting normal vidspeed, but its his own version
normal one can be downloaded here https://thandor.net/downloadmanager/66 4.0
https://vetusware.com/download/VIDSPEED%203.0 3.0
no dos4gw needed. "vidspeed * L" command

https://github.com/raszpl/sigrok-disk FM/MFM/RLL decoder
https://github.com/raszpl/FIC-486-GAC-2-Cache-Module (AT&T Globalyst)
https://github.com/raszpl/386RC-16 ram board
https://github.com/raszpl/440BX Reference Design adapted to Kicad

Reply 19 of 35, by dionb

User metadata
Rank l33t++
Rank
l33t++
myne wrote on Yesterday, 00:50:

[...]

The v means video.
There's no such thing as vram as a product.

No?

Then why does the ATi Programmer's Guide to the mach32 Registers - the only piece of technical documentation of the mach32 in the public domain - explicitly mention this?

Memory Types: VRAM 256Kx4, 256Kx16; DRAM 256Kx4, 256Kx16

- and also go on to indicate which versions of the ATI68800 support which memory technology. The ATI68800-6 on OP's board supports both VRAM and DRAM - but it can't mix both. So it's very relevant to identify whether the chips on the board are DRAM or VRAM. By saying the sockets were for VRAM when he already has DRAM on the board you were inadvertently giving incorrect advice.

An example of an early VRAM chip is the NEC D42274V-10, a 256Kx4 VRAM chip in ZIP form factor, which was definitely used on ATI's 8514/Ultra, would have been compatible with the Mach32 and may also have actually been used on the Graphics Ultra Pro, ATi's Mach32 ISA card with 2MB of VRAM.

I suggest you read up a bit more on 1990s memory technologies before telling others "There's no such thing" - it was a lot more diverse than today. Now - aside from SRAM caches - basically all RAM you'll find in PCs is DRAM. Back in the day dual porting was a thing (allowing the video controller to write to the framebuffer at the same time as it was being read by the RAMDAC), with VRAM as the expensive high-end option for graphics vs DRAM in the low end, and some other oddball options like WRAM (Matrox) and MDRAM (Tseng) trying to approach VRAM performance at cost closer to DRAM. S3's product lineup exemplified this, with the low-end S3 8xx range using DRAM and the 9xx range offering basically the same features but in VRAM. And with a very small number of oddball exceptions, you couldn't mix types on a single card.