A Look at the Short-Lived 3-Inch Compact Floppy Disk

Compact Floppy Disk logoI was recently listening to the latest episode of Retro Computing Roundtable podcast during which there was mention of a 3-inch floppy disk. No, not 3.5-inch, but 3-inch. These disks are known as Compact Floppy Disks (also “CF2”) and were used in a number of systems outside the US, including some models of Amstrad, Tatung, and MSX machines. And, while the Sony-engineered 3.5-inch disks that those of us who don’t think that they are 3D-printed takes on the “save icon” know well are more or less square, these disks are rectangular. This was a curiosity discussed in the podcast at length.

Magazine ad for Amdisk-I driveThe Compact Floppy Disk form factor was engineered by Matsushita and Maxell and, in the states, it was offered for a variety of machines by Amdek as an standalone unit. The Amdek Amdisk-III was a dual-drive unit released in 1982 at an introductory price of $899, offered for the TRS-80 CoCo and the Model III as well as the Atari 8-bit line. Amdek also sold a single-drive Amdisk-I unit exclusively for the Apple II, billed as a perfect second-drive option. I saw an ad for the latter when I was using an Apple IIe as my main system and it appealed for it’s cool-factor, but was too expensive. Eventually I saw a close-out deal for the Amdisk-I at a price of about $75 and I went in on it. When it arrived it came with four blank 3-inch floppies and I plugged it into my Disk II controller card and installed the third and fourth floppy-sides of Ultima IV on it and played away. It was reliable and, as expected, pretty cool.

I sold the system it was attached to and moved to an Atari ST, but I kept one of the disks. After hearing the discussion on the RCR podcast about the oddness of its rectangular form-factor, I decided to dissect the disk I have on hand to see and share just what’s inside. Would there be a magical storage space for trinkets? Something special waiting for the adventurous user who decided to crack a disk open? As it turns out — no. There’s just a spring and an overall situation that presented no particular reason for it being non-square.

External view of CF floppy

Internal view of CF floppy

Having cracked open the disk, I present the photos here for posterity. I’ve been without a drive to read this disk for over 20 years, and so the destruction of the media is of little pain for me. The magnetic media of yesteryear (some even less common than these) is an interesting thing to examine, I think.

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5 Responses to A Look at the Short-Lived 3-Inch Compact Floppy Disk

  1. Paul R. Potts says:

    Wow – I grew up in the early days of home computers (the Commodore PET, the TRS-80 Model 1, the Apple II) and I thought I was aware of just about every product for these machines, including oddball ones like the TRS-80 Screen Printer and the Exatron “Stringy Floppy.” But I don’t recall these at all. Interesting addition to any museum of dead media!

  2. Timex/Sinclair Guy says:

    I have 6 of these, they were standard in the last Spectrum model that Sinclair manufactured before Amstrad took them over. There was a Yamaha keyboard that had this drive in it also. I used one on the Timex/Sinclair 2068 with the Larken Disk System which could accommodate up to 4 drives at once. Rumor had it that Timex was paid NOT to produce the disk drive peripherals by the company that made the PCjr. Since Commodore, Atari and PC’s were available with disl drives, and Timex was still cassette based storage, they went under and pulled the plug for their computer division.

  3. Andy McAdam says:

    I had an Amstrad 6128 which used these. Loved them, so sturdy and robust. Really reliable at the time too.
    Also liked that they were two sided.

  4. Allen Schreiber says:

    There was also the even more niche 2-inch floppy on Zenith notebooks. I only saw it once in person, but I guess I was intrigued enough to remember it.

    http://oldcomputers.net/zenith-minisport.html

  5. I remember using these on Amstrad PCWs. They felt much more solid than 3.5″ disks. I heard somewhere they were designed to be able to go through the Japanese mail system without any special packaging.

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