What are these floppy formats?

Posted by darthuna@reddit | vintagecomputing | View on Reddit | 6 comments

This is from the datasheet of the USB97CFDC USB Floppy controller. I'm confused about the 1.2M Windows J and the 1.2M NEC DOS 6.x formats. Are these just the regular 1.2MB HD 5.25" floppy format?

[-]

Tokimemofan@reddit

NEC PC-9801 hardware had a 1.2mb 3.5 inch floppy format that requires special support. It’s logically compatible with the 5 1/4 format of the same capacity so disc to disc copying was much easier better the 2 physical formats

[-]

Js987@reddit

The two 1.2M formats are Japanese market 3.5” formats. I’ve never seen the “Windows 98” marker on J before, but J and NEC I’ve seen and are just 3.5s formatted differently.

[-]

nmrk@reddit

I would pay good money for an S-100 board with Flash memory on it, emulating a full CP/M filesystem. I have an old SOL-20 but I could not afford the fantastically expensive Processor Technologies Helios 8" floppy drives. I couldn't afford third-party 5in floppy systems like North Star, the price of S-100 computers alone was so high, it was hard to afford "luxuries" like disk storage.

[-]

kodabarz@reddit

There were a lot of floppy disk formats. NEC used some unusual ones for its computers (especially the PC-98) and Microsoft used DMF for installation media to give higher storage capacity. I don't know what Windows 98 J is in particular though.

https://en.wikipedia.org/wiki/List_of_floppy_disk_formats

[-]

gihutgishuiruv@reddit

J == Japanese format

While the more common 1440 KB format spun at 300 rpm, the 1.2 MB formats instead spun at 360 rpm, thereby closely resembling the geometries of either the 1.2 MB format with 80 tracks, 15 sectors per track, and 512 bytes per sector previously found on 5.25" high-density floppy disks or the 1.2 MB format with 77 tracks, 8 sectors per track, and 1,024 bytes per sector previously found on 8" double-density floppy disks

https://en.wikipedia.org/wiki/Floppy_disk_controller

[-]

Scoth42@reddit

Not 5.25", they're special formats used by specific Japanese computers with 3.5" floppies. In particular, the NEC PC-98 systems. They were a series of non-IBM-PC-Compatible systems that ran ports of DOS and Windows, but mostly would only run specially-ported software. As far as I know there's still no USB Mass Storage compliant 5.25" drives outside of some hobbyist efforts.

https://en.wikipedia.org/wiki/PC-98