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View Full Version : Very Bizzare Brown PCB 64K-256K XT Board Floppy Discovery



Mad-Mike
July 9th, 2006, 08:48 PM
Somehow, by some surprising stroke of weirdness, I have managed to get this thing to boot off of a MaxBlast diskette containing Caldera DR-DOS 7.x and a 1.44MB Floppy formatted as a 1.44MB Floppy on a NON BIOS controller using a standard, modern, EPSON 1.44MB Floppy Drive from the mid-90's. There is no BIOS on the controller. I had to hit F8 to bypass the startup files, but otherwise, it works for all reasons and purposes. Even ran a chkdsk, and it said the diskettes total size was 1.44 MB (or the really long interger that equals to that in short form).

As for the floppy controller, it's a 16-bit Floppy Drive/IDE Multi-I/O Controller with a UMC 8388 chip (the large IC), and says KMP INTL 042399 on a sticker on it, and it's also a Model I20-B. SO obviously, if you're desparate to get an XT to boot, get a copy of MaxBlast from Maxtors website, and one of these controllers, and an Epson Floppy Drive, and you'll be able to boot it up, just remember to keep pressing F8 through startup till the Keyboard buffer overflows, that's how I bypassed the startup files. Anyway, I'm off to do more experimenting, this means I can finally USE this computer, even though I need a hard disk controller, and hard disks if I'm stuck having to use MFM/RLL technology (I've got plenty of IDE drives that'd work fine).

On top of this, I plan to document how to do the 640K Motherboard upgrade. I'm using the Brown board for the upgrade, the Green one is for a restoration project (I'm essentially going to re-create an original IBM PC XT 5160 from 1983 with it, 10MB Drive and all, working on it as time/money allows).

Terry Yager
July 10th, 2006, 09:27 AM
M-M,

If you're talking 'bout the boards I sent ya, one was pulled from my IBM 5155, and the other came from my Industrial-Grade case, but I don't remember which is which. Keep in mind tho, that the industrial case is an A-B re-badge, so there may be some difference in the ROMs (never occurred to me before). When I aquired the case, the drives were already stripped from it, so it may have originally had a 1.44 drive & a custom ROM to recognize it.

--T