An Eight Inch Floppy For Your Retrocomputer

For people under a certain age, the 8 inch floppy disk is a historical curiosity. They might just have owned a PC that had a 5.25 inch disk drive, but the image conjured by the phrase “floppy disk” will be the hard blue plastic of the once ubiquitous 3.5 inch disk. Even today, years after floppies shuffled off this mortal coil, we still see the 3.5 inch disk as the save icon in so many of our software packages.

For retro computing enthusiasts though, there is an attraction to the original floppy  from the 1970s. Mass storage for microcomputers can hardly come in a more retro format. [Scott M. Baker] evidently thinks so, for he has bought a pair of Qume 8 inch floppy drives, and interfaced them to his CPM-running RC2014 Z80-based retrocomputer.

He goes into detail on the process of selecting a drive as there are several variants of the format, and interfacing the 50 pin Shuggart connector on these drives with the more recent 34 pin connector. To aid in this last endeavour he’s created an interface PCB which he promises to share on OSH Park.

The article provides an interesting insight into the control signals used by floppy drives, as well as the unexpected power requirements of an 8 inch drive. They need mains AC, 24VDC, and 5VDC, so for the last two he had to produce his own power supply.

He’s presented the system in a video which we’ve put below the break. Very much worth watching if you’ve never seen one of these monsters before, it finishes with a two-drive RC2014 copying files between drives.

We’ve had surprisingly few 8 inch floppies here on Hackaday, probably because they never really made it into home computers. We did however review the RC2014 last year, as well as looking at [Scott]’s original build.

39 thoughts on “An Eight Inch Floppy For Your Retrocomputer

  1. This is an awesome project! I have bunch of 8″ floppies still somewhere around, i remember they contained backups and some software for CP/M. 8″ drives are nowadays quite a hard to find.

    I wonder, could the data still be intact in those floppies…

    1. You might be pleasantly surprised. If they were stored well, it’s entirely possible that the data would be 100% readable. I’ve recovered data from 8″ diskettes that were over 30 years old. In one batch of 100 diskettes, only 2 of them were unrecoverable. Some brands are worse than others, of course.

      1. They must have been made with better quality media than the junk that 5.25″ floppies were made from. I never had any of my disks last more than 5 years, despite taking proper care of them. Of course, it could be that my drives went out of alignment.
        Never did much with 8″ floppies. Home computers had moved on (backwards, actually) to tape decks by the time I got my own computer.

        1. 8-inch floppies were never really consumer spec products, and the manufacturers knew their customers expected quality and would be good for large orders if it was delivered. They were also very low density by even 5.25 inch, much less 3.5 inch, standards and so small defects were more tolerable.

  2. I have kept my 8-inch floppy drives because I remember 20+ years ago reading that a researcher of some sort had been running an experiment for about 20 years. That particular year he had finally gotten the last bit of data but then he realized something horrible, he had forgotten that his initial data was stored on an 8-inch floppy and he didn’t have access to one. I realized this would be a very common thing and I’ve seen it more and more. For example, our local college radio station used to have some awesome station ID commercials. A few years ago I asked if they still had them on tape. The reply was, yes, but they’re locked away on the old radio cartridges and their player had died years go so nobody could retrieve them.

    We’ll see this more and more with older SCSI and IDE drives, and when was the last time you saw a computer with an MFM controller? That old hardware can be worth a fortune if someone has something locked away that they need back.

    1. I have made a lot of money off of my Bernoulli drive and my desktop 9 track tape reader. Every time I was asked about data conversion and told them my rates AND “no guarantees at all on data retrieval” they would say I was outrageous and then come crawling back about a week later.

      Made enough to buy several new computers and a new car in the early 00’s from gear retrieved from a trash bin.

    2. >> For example, our local college radio station used to have some awesome station ID commercials. A few years ago I asked if they still had them on tape. The reply was, yes, but they’re locked away on the old radio cartridges and their player had died years go so nobody could retrieve them.

      If the stn IDs are on the standard NAB broadcast cart format, it’s 1/4″ tape that runs at the standard 7.5 ips speed, but possibly in an oddball track format. The tape can be carefully removed from the cartridge (they’re designed to come apart), cut at the splice, some leader tape added to each end, then played on just about any decent reel-to-reel machine.

      (there must have been a master tape of those ids that they dubbed to cart. Shame that they didn’t preserve those)

      Back on topic, yes the old floppy drives are great… as a source of stepper motors. Other than that…

    1. I seem to recall them holding 160kB on the VAX 11/780 at school. I don’t remember them being noisy (as compared to the teletypes, air conditioners, and other typical computer room noises)

        1. Yeah, I seem to remember a brief early 80s flurry of interest in them from hobbyist power users, just for capacity, because they got the HD upgrade a bit before 5.25 did. Mostly I think from the CP/M crowd… then of course, HDDs began to be less than the price of a midrange car, and took over.

      1. Compared to what replaced them. We did not use cassette based systems where I worked. Furthermore we had to keep using these old drives well past the point they were cutting edge. I was glad to see them go.

    2. A typical DSDD soft-sectored 8″ drive holds 1.2MB. And I still have 3 Qume DataTrak-8 drives in the basement, sitting right next to the IMSAI, which is outfitted with a Zilog 8MHz Z80H CPU (has to be clocked at 4MHz for the front panel to work), a Tarbell DSDD floppy controller, 64K SRAM board, 256K RAM drive board, GPIO board for the Diablo HyType-I printer I no longer have, and a locally produced 4-port serial card.

      1. The 8″ floppies on the DEC PDP/11’s I remember were like 360k. And the new floppies I was able to buy in the early 90’s were significantly less after formatting. I suspect they were old stock, but I had to take whatever I could get.

      2. The PDP RX01 and RX01 floppy drives are singles-sided. The RX01 was 256K and the RX02 was 512K. Both drives have 77 tracks and 26 sectors per track. The RX01 used 128 byte sectors (SSSD), while the RX02 used 256 byte sectors (SSDD).

  3. I had a bunch of 220VAC 8-inch floppy drives, in the USA. The analog power supply transformer commonly had two 110VAC primary windings that were wired in parallel for 110VAC or in series for 220VAC. To get 220VAC for the floppy drives, I wired the transformer primaries for 220VAC, then wired the 110VAC line voltage to one side and the center tap on the series primary windings, and extracted 220VAC from the outer legs of the series windings. This configuration is know as a step-up auto-transformer. It worked great, though reduced the available power supply current by half (not a problem in this case). I still have them, plus a dual-head servo-drive 8-inch floppy drive (new in box, stored after testing).

  4. Ah, the 8″ floppy. I had an Atari, with some magic interface, and I ran 4 8″floppy drives for a BBS back in the early 1980’s. Even then it wasn’t easy to find disks, but I seem to recall that they were the equivalent of 4 SD Atari drives (memory is foggy, but it was enough storage to be worth it). Later I replaced them with double sided, double density 5.25″ drives that were far faster.

    Good times.

  5. If I had only known. I’d have saved that old Mohawk system and 25 years later, I’d still bet nobody would want it. Now the System32 running DisplayWrite used the 8″ floppy in magazines, far more modern.

  6. I still have 8 or more 8″ floppy drives. One of these days I should get them out of storage and see what I can do with them. Two of them are in an old Radio Shack TRS-80 Business computer. (I think that’s what it was called.) Two are in an enclosure with an interface to an Apple II computer. Two are in a homebrew Motorola Exorcizer 6800 development system. The other two are part of an old 8088 style SCADA computer that monitored part of the electric grid. Oh the fun! I think I still have some boxes of brand new 8″ floppies. Some are “Elephant” brand, so I’m sure they will never forget and lose data. Actually I think two earlier forms of storage for microcomputers were cassette tapes and punched paper tape. I think Southwest Technical Products made both. The tape interface was an AC-40. (but I could be wrong – It’s in storage too)

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