Eight inch disks are both a blessing and a curse in the retro computing world. They’re awesome in that for the time, they stored a generous amount of data - even a single density double sided 8” diskette could hold half a megabyte, which was impressive considering early microcomputer hard drives (such as Apple’s ProFile) topped out at only 5 megabytes.
The problem with eight inch diskettes today is not so much the disk capacity, or even obtaining blank media (it’s still surprisingly easy to find inexpensive media thanks to IBM’s support of the format long after the microcomputer industry had moved on). The issue is how to get new data on one of these beasts in this day and age.
Some back story is in order. One of my recent Craigslist fueled acquisitions was an absolutely beautiful TRS-80 Model II with all the trimmings. The Model II is a very rare backplane based Z-80 system in the spirit of the S-100 style machines - separate cards for disk control, CPU, video, etc. situated on a “dumb” backplane coupled to a eight inch diskette drive.
The “trimmings” I mentioned included everything from original media, manuals, cables, books - even an unopened box of original TRS-80 Model II diskettes still in their shrink wrap! Despite the glory of the haul (all for $20), I soon ran into a rather large issue.
The problem became apparent as I tried to boot the system from the original TRSDOS floppy. After several unsuccessful attempts, I discovered that the magnetic coating of the diskette was literally wearing away where the read heads had touched it. You can clearly see the ring patterns in the shot below.
Of course at this point I cleaned the drive heads, but it seems this phenomenon is more due to the age of the media than any abrasive residue left on the heads themselves.
Afterwards, I found a backup TRSDOS floppy in the morass of diskettes that came with the machine which did boot successfully. No problem - simply copy the working TRSDOS diskette to a fresh blank, right? Unfortunately, no - for some reason, even though the diskette seems to boot and operate just peachy, it won’t copy; errors out with a message that the boot sector can’t be read. It too is probably on its last leg, and I’m reluctant to use it much considering the same fate could easily befall it. The Model II is useless without a bootable OS diskette - it has nothing in ROM to fall back on.
Now we get into the nitty gritty. There is a way to get fresh TRSDOS floppies, even a newer version than the one I have now. Also, a CP/M by Pickles & Trout is readily available. The catch? The software is only available on disk images that must be downloaded and written out to eight inch disks via a PC using MS-DOS. Yuck.
I did put out some feelers to see if I could locate someone who had already assembled such a system, maybe to create media for S-100 systems (or even a Model II). Unable to find any leads, I resigned myself to assembling my own imaging system.
Some of the first parts have begun to trickle in. I picked up a couple new boxes of eight inch floppies off eBay for $15 per box of ten. I also purchased a throughly nifty eight inch drive adapter card from D-Bit that should make hooking up an eight inch drive to a PC a much easier task. Oh, and I bought a Shugart 801 diskette drive similar to the one found stock in the Model II.
What remains is to locate a PC with a compatible floppy controller chipset to do the grunt work and some sort of external chassis or power source for the eight inch diskette drive. As I work through these remaining issues I’ll post updates on them. Should be fun, and hopefully once this is all up and working I’ll be able to offer pre-made floppies to others so they won’t necessarily have to go through the same pain themselves.
And now I’m off on vacation for a week to take a break from the grind at work, so blog posting will most likely halt for a bit. Until then, happy computing!