Jumper settings and Floppy Controllers

[superspork]

I have recently acquired a 486 motherboard from my local surplus chain. The man I bought it from told me it was originally the guts of an old arcade machine that he had cannibalized for the trackball. It didn't have a processor, but I found one at an electronics recycler for a good enough deal.

The motherboard is an EPoX (based on the Award BIOS code), unknown model, but the jumper functions are all pretty labeled on the board. The processor I got is an ST486DX2-66GS. The motherboard is a Socket 2 (4 rows of pins, no key in the corner), this one only has 3 rows (Socket 1?); this doesn't seem to cause an issue, however.

As the board was originally an arcade board, it didn't have some of the usual features, like floppy or I/O on-board; it came equipped with a ROM board and an extra interface card for the arcade controls, both of which I removed. I bought an I/O board from eBay to supplement it. However, it's not running like I would expect. FreeDOS runs without issue (most of the time). MS-DOS, however, has issues. My MS-DOS 6.22 disks won't boot at all; I have DOS 6 install-to-floppy disk I tried as well without success. It also occasionally will freeze.

All this being said, I have two general questions:
1. Which is a more likely culprit -- the cheap I/O board from eBay, or the board jumper settings?
2. Can anybody recommend a good quality (and preferably well-documented) ISA-based floppy controller? Even a combination card is fine, just as long as it works.

Thanks!

 

[Chuck(G)]

Combo IDE+Floppy controllers should still be plentiful out there, as well as SCSI+Floppy controllers (e.g. Adaptec 1542C). When 486 boards first came out, they were simple processor boards without any sort of on-board support. Those are going to be your cheapest 286+ alternatives. (Yes there are dedicated floppy boards, but you'll pay through the nose for the ones that support high-density drives).

Are perhaps your DOS install floppies high-density and your multi-I/O board really for the XT-class machines? Specifics help a lot in diagnosing your problem!

 

[superspork]

They do indeed seem to be plentiful, given the amount available on eBay. But I'm not sure as to quality and such.

The card I have is labeled "W83777 Ver 1.0" which seems to be made by Fujitsu. There's two chips on the board -- Both from Winbond, a W83787F and a W83758F. The former appears to be the more important and (from what documentation I have found) should support high-density floppy drives. My FreeDOS disk is a 1.44 mb disk, and it boots fine as well. I plugged in a 1.44mb 3.5" drive and a 1.2mb 5.25" drive, which both read disks (under FreeDOS). I'm just puzzled at the whole thing, as this seems to be a stability issue more than anything.

Previously, I noticed a small scratch between two legs of one of the chips, but I have disregarded it so far as it seems to work okay still.

I've also found motherboards that use the W83787, but the only jumpers they ever document are the ones that are actually properly marked on my card.

Other interesting tidbit: My processor is recognized in the BIOS as a Cx486DX2-S, which is not what I have. I've tried a few combinations of jumpers, and this doesn't ever seem to change. Don't know if this is relevant.

 

[Chuck(G)]

I assume that you've configured the 1.2MB in the BIOS as a 1.2MB drive. Someone recently sent me a TD0 file where the 1.2MB drive was set up as a 1.44MB drive. High-density disks will read just fine in that setup, but not DD floppies. Try formatting an HD floppy with your 5.25" drive and reading it back; then try the same with a DD floppy, formatting it as a 360K.

 

[superspork]

The plot thickens.

I bought a new floppy controller from eBay since I no longer trusted the one I originally purchased. I bought an Adaptec AHA-1522A, which I could very easily find documentation for. (Kudos to Adaptec for supporting their old products.) I reset the jumpers to factory settings, as per the manual, and installed the card. The BIOS on the card seems to be working fine as well, and it tries to scan for SCSI devices, of which there are currently none.

I then connected my floppy drives and set them up in the BIOS again. As before, FreeDOS loads fine, but MS-DOS 6.22 refuses to load. I have two sets of disks -- one is the original Microsoft set for installation to a hard disk (3 3.5" floppies), the other is the startup disk that came with an old Pentium system many years ago. I know that my disks are good, as they boot just fine in several other systems. The failure I am seeing is that it loads from the floppy for a few seconds, probably initiated by the BIOS, prints "Starting MS-DOS..." to the command line, and then does nothing.

I am convinced that the Adaptec controller I have is good, and at the very least I am seeing the same failure pattern that I saw before. Therefore, I am convinced that the problem does not lie with my floppy drives or controller, but lies somewhere on the motherboard, either with BIOS setup issues or with bad jumper setup.

The BIOS is an Award "ROM ISA BIOS", Award ID 2C4I9PA0. The CPU is an ST486DX2-66GS (as I said before.)

Specifically, this is what I am wondering:
1. CPU and motherboard compatibility. What should the CPU be configured as? A DX2, a P24D, or what? Should I just buy an Overdrive CPU instead?
2. BIOS settings. I don't know 100% what to do here; I'll get more specific if requested.
3. Does DOS 6.22 need a hard disk to boot, even from floppy?

 

[superspork]

I figured it out!

After a few hours of twiddling with jumpers and BIOS settings, I found out that it was, in fact, a bad BIOS setting. I changed it myself, too.

For my setup, "Internal Cache WB/WT" under "CHIPSET FEATURES SETUP" should have been set to "Write Thru". I had it set to "Write Back." All problems resolved.