Micro Data PC230 (South Australian computer)

Alexis thrashbarg at kaput.homeunix.org
Wed Jul 23 23:08:43 CDT 2008


A while ago I got one of these off a friend of a friend and got it going a few 
days ago. I was wondering if anyone had any information about it, 
specifically a technical reference manual. I'd like to have a closer look at 
its architecture, just out of curiocity and for this...

The hard disk interface is a WD33C93 and has a BIOS to let MS-DOS access it. 
It currently has its original 20MB Miniscribe hard drive internally and I 
attached an external 140MB 5.25" SCSI drive.

Just as an experiment, I attached a CD-ROM drive to it and set the number of 
SCSI drives to three. It detected the CD-ROM drive when there was a disk in 
it, but MS-DOS doesn't natively support ISO9660 drives. So I made a 20MB hard 
disk image in QEMU, partitioned it in FDISK and formatted it, then burnt the 
image to a CD. MS-DOS detected it as a drive first go. This shouldn't be a 
surprise if you know a thing or two about the SCSI architecture.

This makes me wonder if there's such thing as an ISO9660 extension for MS-DOS 
that will let me access CD's in this way. The issue is if I don't have a disc 
in the CD-ROM drive when it boots it will fail to detect the drive.

The other option is writing a driver for the WD33C93...



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