On Jul 29, 2019, at 7:53 PM, Herb Johnson via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
I can't imagine it's a problem for you [Ethan], but if you need hardware, let me know! - Jonathan
I'd also be glad to help Ethan and or Dave Riley. But floppy drives I have should be readily available to them. Apparently the previous maintainer was using a 3.5" 1.44M drive, presumably on some generic PC of some sort.
The fun stuff would be to extend the PC floppy drive to support 8-inch again. There's a few MS-DOS formats for that.
But I don't know which flavor of controller-chip the Linux kernal-driver currently supports. Our friends may need help on those details.
The most-recent kind of floppy-controllers on PC class mobos, is/was probably embedded deep inside one of those "Super I/O" surface-mount chips. While specs on FDC's go back quite aways, there's the troublesome issue of modes of operation; particularly single-density. Density operation depends somewhat on how the read data-stream is decoded with phase-sensitive hardware.
I'm not aware of a PCI floppy controller board, as an upgrade to a modern PC. And I think the various USB floppy devices are another class of driver, my guess.
At this point I'm out of my depth, on modern details. I'm just pointing at the gotcha's I'm vaguely aware of. I doubt modern Linux supports more than DD/HD 720K and 1.4M and 2.88M 3.5" diskettes in MS-DOS FAT format. Maybe 1.2M/360K 5.25-inch, as did PC mobos a generation ago. And of course, Linux has "dd" which just writes out sectors of data (still to some kind of formatted diskette).
Last I checked, though it's been quite a while, the Linux floppy driver supported a wide range of historical controllers. The interesting thing will be supporting those, and possibly sorting out which ones are still supported by modern Linux (though realistically, since you can still get PCIe->ISA bridges and chassis, you should be able to support anything, so no real reason to cull). USB floppy drives are just Mass Storage devices, for the most part. That's why you'll generally never find one that supports Mac 400/800K disks; the controller is on the drive, and the controller doesn't do GCR, so no dice there. Most of the stuff in the SuperIO chips just emulated reasonably recent discrete chips; it's not like the controller changed much after the high-density 3.5 floppy (most of them support 2.88MB drives, but I definitely don't have any of those). Making 8" work again would be pretty neat, agreed. Probably not too hard, realistically speaking. I have enough 3.5" drives (of the standard HD persuasion, no 2.88MB ones), and I have a few 5.25" 1.2MB drives. No double-density or lower, which I gather are relatively rare these days at least as far as PC drives go. The real rare thing is round tuits, so I'll see if I can find any of those.
"SWIM3 driver for NetBSD"? (shiver) That would be a PowerPC Mac reference, or maybe 68K Mac? I guess I could run NetBSD on my Mac IIci as a server, for what I'm not sure... ;) or a 7100.... It's all good of course.
Yup! SWIM3 was only on the PowerPC Macs and I think maybe the AV macs; it's basically a DMA-capable SWIM2, which itself was a cost-reduced, reliability-enhanced SWIM (which was the IWM with a very clever MFM mode added to handle PC disks, and the IWM was basically a Disk II on a chip). NetBSD doesn't have a SWIM3 driver, though it has a SWIM driver; I have a bunch of docs (which I've uploaded to the Archive) that cover everything that *should* be needed. - Dave