According to the manual my board supports IDE LBA and IDE 32-bit mode. I'm assuming that would give me at least 2gb with LBA enabled as long as the controller I use doesnt have a separate bios, so my Caviar 1.8gb should work, correct?

The bios (according to the documentation i have) is dated 7/1995, so this boards bios is quite "new" for a 486 VESA board as far as I know. I would expect support for larger than 500mb drives by then, but who knows 😎

Yeah, that should do the trick. That's newer than my JX30GC, which does have LBA support. (It has an integrated VLB disk controller, however.)

28 bit LBA could be limited to 8.4G, 32G, or 137G depending on the BIOS implementation.

Awesome, I should be able to run my old drives then. I also noticed I have a 4 gig compact flash sitting in a camera i never use because the flash bulb died.. Maybe I'll order an ide to flash adapter

137 gigs would be hilarious for a dos 🤣. Does win95 support fat32? Just curious, this machine is for dos + windows 3

Win95 doesn't, but Win98 does (and Win98 will run on a 486, but make sure you have enough RAM, 32MB+). There are a few DOS variations that do too, but all of them have various caveats and limitations. (Also, you get FAT32, you don't get LFN support, mostly.)

You *can*, however, have the first 8GB diced up into partitions for DOS and have the rest allocated to OS/2, Windows NT or something else that groks big disks.

If you get a CF adaptor that mounts on a I/O bracket you can swap CF cards like console a cartridge if disk space gets to be an issue.
That's how I do it. C:\ small noisy drive for retro boot sound goodness.
D:\ CF card for games when I'm not actually interesting in hearing the drive

BeginnerGuy wrote:

Does win95 support fat32? Just curious, this machine is for dos + windows 3

jade_angel wrote:

Win95 doesn't, but Win98 does (and Win98 will run on a 486, but make sure you have enough RAM, 32MB+).

Actually, Windows 95 OSR2.x has built-in FAT32 support. I can confirm this because my OSR2.1 CD formats hard disks larger than 2GB as FAT32 which allowed me to make full use of my 6.4GB and 13GB hard drives without any empty partition space.

jade_angel wrote:

Win95 doesn't, but Win98 does (and Win98 will run on a 486, but make sure you have enough RAM, 32MB+). There are a few DOS variations that do too, but all of them have various caveats and limitations. (Also, you get FAT32, you don't get LFN support, mostly.)

You *can*, however, have the first 8GB diced up into partitions for DOS and have the rest allocated to OS/2, Windows NT or something else that groks big disks.

That could be fun, though I really have no need to push this system that far since I already have a Slot 1 rig and probably soon S7. Could be interesting to fool around with OS/2 or NT though, that's something I haven't thought about. No matter what though, this computer will only be running one drive as the case I bought is super small, the only space for a hard drive is in the floppy cage unless I get a 5.25 drive bay, but I want a 5.25 floppy too. So I like the idea of one larger drive split up into a couple of 2GB partitions.. Not that I really need that much space 😊

chinny22 wrote:

If you get a CF adaptor that mounts on a I/O bracket you can swap CF cards like console a cartridge if disk space gets to be an issue.
That's how I do it. C:\ small noisy drive for retro boot sound goodness.
D:\ CF card for games when I'm not actually interesting in hearing the drive

Is there one like that you can recommend that should work? I've read it's a bit of a gamble with IDE to CF cards, and then another gamble depending on which CF card you use. Hopefully I can buy a combo that works. This idea really stands out to me now that I've seen how tiny the case I'm using is, any space saving will be very nice.

Here's a quick look at my new case.. It didn't come cheap, but I think that dual bay PCMCIA drive may be worth a decent amount of money if I resell it. The SCSI bay up top doesn't have the caddy in it sadly.

I'm flat broke right now, so it's going to be a bit until I can get anything else (I still need a HDD controller, GPU, and mouse). I'm going to strip out whatever is in this case now and retrobrite it with some salon hair products in the mean time 😎 ...

Oh and any turbo wizards want to take a crack at this for me?? :

Looks like two columns of 11 jumpers, the left row is labeled D-N and the right is labeled 4-14. There are also two more sets of 3 jumpers down the bottom. I've never seen a setup like this before, I can't think of how it works off hand. So far all I know is that turbo off seems to be set to 08, not sure about on.

That case looks like the ones we had in high school, and have shown up here a few times as well.
You can just mess round with the jumpers with the PC turned on. It wont hurt anything.

I don't think My CF adaptor is anything special, It does have a jumper for primary or slave, it was listed as
"40-pin IDE Connector (male) CF to IDE Compact Flash Card Adapter Bootable" but typical Chinese seller isn't on ebay anymore, I got mine 2 years ago
CF cards I got were Sandisk 4GB Ultra, but if your using a real HDD for C:\ then the whole bootable thing isn't an issue anymore anyway!
One thing is AutoDetect doesn't work on my 486, I do have to manually set the parameters in BIOS

I'll mess around with the turbo and see what happens.

I've narrowed down that PCMCIA drive to a Sun Microsystems Swapbox PNP dual PCMCIA reader. I tested it out in windows 98 and it auto detected and installed itself once I plugged the SCSI cables into the drive, but it doesn't seem to want to read the one card that I have which is a Trendnet TEW-421PC (wireless G adapter). The Trendnet card works in my Thinkpad with Win98SE but I'm just seeing "slot empty" on this. My luck streak continues 😒, or maybe this card just doesn't work with it? It says this drive takes Type II and III PCMCIA. I know nothing about these though.

Edit: Got the segmented display set up to 08 / 66.. Was disturbingly easy compared to my old one. Right column controls turbo off segments, left column turbo on. Off to the side are 2 banks of 3 jumpers each which control the top 3 segments for on and off. Ahh.

Sigh. No post, no beeps, no nothin. I'm out a lot of money this year and STILL no DOS pc 🙁. VLB boards are ridiculously expensive on ebay, so I'll have to spend another X amount of time hunting deals and by then I'll lose any chance of returning other parts I just bought.

- I tested the power supply under stress with a friends pentium mmx 166 (AT board), no problem
- I tested the 16 MB memory I had from my original 486, many passes of memtest, no problem (will post pics of it soon, I'm pretty sure it's double sided non parity FPM 72 pin, will add pics).

I have no way of testing the AM5x86 133, I have no other socket 3 processors or boards on hand and I still don't have a multimeter to test the vrm. Same goes for the controller and video card.

Sigh, anybody have any miracle potential ideas? I've about had it with my quest for a retro PC but I have to get this one working after all the money invested in the case, PSU, and VLB components.

Documentation on the board: http://stason.org/TULARC/pc/motherboards/A/AM … 0-VER-1-75.html

I've highlighted the cache and bus jumpers, which should reflect 128k l2 cache and 33mhz fsb

You seem to have a keylock header, it might need center pins shorting.

edit: yeah damn, according to the socket and the silkscreen the BIOS is upside down. No clue whether it's even the right chip, I HAVE seen "too big" sockets for 64/256kb chips, but no clue if it goes top or bottom or even if this was one and you have the right chip.

BitWrangler wrote:

You seem to have a keylock header, it might need center pins shorting.

edit: yeah damn, according to the socket and the silkscreen the BIOS is upside down. No clue whether it's even the right chip, I HAVE seen "too big" sockets for 64/256kb chips, but no clue if it goes top or bottom or even if this was one and you have the right chip.

Thanks, I just tried shorting the keylock header but to no avail. I had that plugged in when it was in the case, according to the manual pin 4 is keylock and pin 5 is ground.

Upside down bios.. This is some "pulled from a working unit" board I got myself into 🤣 .. Perhaps that explains why it gets so hot when it starts. That prom is getting hotter than the CPU does to the touch. I suppose it wouldn't hurt to try to rotate the chip around.

Just found this M912 V1.7 pic online, different marking but looks like the chip is flipped around (unless the sticker on mine is upside down 😒 )

Edit: Flipping around the bios chip as above (left 4 pins open) yields no change and the chip no longer heats up (CPU still heats up). I also tried removing all l2 cache and testing without, still nothing.

I can hear Dr. McCoy in my head telling me it's dead 😊

if you look close the notch in that chip is facing upwards. I think your bios chip could be dead from reverse insertion though because it looks a bit like a burn blister on it, in the close ups from before.

BitWrangler wrote:

if you look close the notch in that chip is facing upwards. I think your bios chip could be dead from reverse insertion though because it looks a bit like a burn blister on it, in the close ups from before.

Seems like it's just the sticker peeling off a bit, the top of the chip is still smooth. Either way that could explain it. I'm figuring either that or the previous owner fried the CPU running 5v through it. There are no signs of obvious damage anywhere, the entire board seems in immaculate condition. I wish I had equipment for further testing, but it would probably be cheaper for me to just grab a replacement. I was looking forward to messing with a 5x86 on a vlb board 😒

BeginnerGuy wrote:

BitWrangler wrote:

if you look close the notch in that chip is facing upwards. I think your bios chip could be dead from reverse insertion though because it looks a bit like a burn blister on it, in the close ups from before.

Seems like it's just the sticker peeling off a bit, the top of the chip is still smooth. Either way that could explain it. I'm figuring either that or the previous owner fried the CPU running 5v through it. There are no signs of obvious damage anywhere, the entire board seems in immaculate condition. I wish I had equipment for further testing, but it would probably be cheaper for me to just grab a replacement. I was looking forward to messing with a 5x86 on a vlb board 😒

Not all hope is lost. You could track down the MB model and flash another EEPROM for it and check if it's alive.

There's a 5x86 BIOS for the M912 you can grab from here and flash onto a spare EEPROM using another motherboard. You'll have to take care of the orientation though. Looking at your board, the PIN1 notch is on the left, so the notch on the EEPROM must be oriented to the left. This is one reason why the BIOS chip you have in there might be dead for good - it was oriented in reverse and thus recieved voltage on the wrong pins, causing it to burn up, even if you don't see any burn marks.

Thanks for the reply, I'm considering what I'm going to do. I think for now I'm just going to go back to hunting ebay for an affordable board and see what I can do for this one in the future when I have more spending cash. Also another board would make diagnosing parts a bit easier. I don't have an EEPROM burner or any spare boards remotely from this era.

I'm messaging the seller just to point out that it obviously was not a "working pull" too.. 😒

Ouch. BeginnerGuy - you have been through a lot of pain with your system work. I've been through a few of your threads, and you face adversity with your parts & just soldier on. So - words of encouragement here for you, because man... sometimes these parts just seem out to get you (didn't you have a case that held a charge and buzzed you when you touched it?).

I am curious what the seller is going to say. Despite the ability to just write another EEPROM in attempt to get going again, the fact of the matter is what you just stated - not a "working pull."

I know that buyer/seller communication can be like walking on pins and needles when it comes to situations like this, but I would push hard for a full refund.