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Thread: Did they make serial or parrelel port PC floppy drives?

  1. #11
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    There's USB floppy drives and I'll guess a USB to RS232 adapter could turn it into a serial port drive.
    Crazy old guy with a basement full of Pentium 1 laptops and parts

  2. #12
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    Quote Originally Posted by DeltaDon View Post
    There's USB floppy drives and I'll guess a USB to RS232 adapter could turn it into a serial port drive.
    No. Just... no.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  3. #13
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    Quote Originally Posted by DeltaDon View Post
    There's USB floppy drives and I'll guess a USB to RS232 adapter could turn it into a serial port drive.
    One could wish that it worked like this. However, it doesn't.
    Most (perhaps all) usb floppy drives that that you can buy today are usb mass storage devices, and furthermore, those drives only understand a limited set of floppy formats.
    usb to serial (rs-232) adapters require that you have an usb software stack that understand usb serial ports on the device you plug it into; those usb floppy drives don't have that.

    In theory, one could plug a usb floppy drive and a usb to serial adapter in a machine, and write a program for that machine that would make the drive behave like a serial floppy drive; you would still be left with the problem that the usb floppy drive only supports a limited set of floppy formats.
    AFAIK, most external drives for classic laptops are (as already noted earlier in this thread) use / abuse a parallel port interface; the few serial ones that I know of are proprietary and different from vendor to vendor. So you would have to reverse engineer the protocol used and re-invent your little serial floppy drive every time.

    Better solutions have already been mentioned in this thread.
    Torfinn

  4. #14
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    Quote Originally Posted by tingo View Post
    In theory, one could plug a usb floppy drive and a usb to serial adapter in a machine, and write a program for that machine that would make the drive behave like a serial floppy drive; you would still be left with the problem that the usb floppy drive only supports a limited set of floppy formats.
    Actually you can't do that, not with a "normal" USB serial adapter or floppy drive. USB is a Master-Slave protocol; the USB root hub/controller inside your PC coordinates all communications between itself and any attached peripherals. There is *no* capability in classic USB for peer-to-peer communications between slave devices, so if you just tried directly wiring between those two devices or plugging them into a powered hub there's no way you could make the serial device initiate communications with the floppy drive by banging away at the RS-232 side; it's just going to sit there drooling waiting for a USB controller to initialize it.

    The only way you could convert a USB floppy drive and a USB serial adapter into a "Serial drive" would be to insert "something" that has a USB master controller in between them, which would run software to grab bytes from one and pass them to the other. Theoretically there's a number of microcontrollers that have sufficiently featureful USB root hubs built into them so, sure, it would be doable, but not without that third piece.
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  5. #15
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    uh, yeah "a machine" I called that third piece. Perhaps I should have written "a computer" instead.
    Torfinn

  6. #16
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    Quote Originally Posted by tingo View Post
    uh, yeah "a machine" I called that third piece. Perhaps I should have written "a computer" instead.
    Sorry. I interpreted "machine" in your sentence as being the "machine" attached to the serial adapter's RS-232 plug, not the thing you need sitting between the two dongles. So yes, we said basically the same thing.

    As a general rule people should remember that once you get beyond passive wiring adapters most conversion dongles are unlikely to just naturally work "bi-directionally". If I had a nickel for every time I've seen someone toss out on a web forum the idea that because, say, PS/2 keyboard to USB port dongles exist you should be able to turn one around and use it to add a USB port to something I'd... I dunno, have a few bucks?
    My Retro-computing YouTube Channel (updates... eventually?): Paleozoic PCs

  7. #17

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    Those Backpack floppy drives work a charm like Chuck suggested. They just work in most scenarios. Great tool to have.

  8. #18
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    There are actual serial port floppy drives that existed. The external 3.5" drive for the Model 100/102 (Tandy TPDD) is one of them. There are emulators for that drive, such as the "NADSBox" that may be adaptable to your use. Somebody else made a "general purpose" serial port 5-1/4" floppy back in the day. One of the avionics companies I worked at around 2002 had one in a test fixture they used in manufacturing. I think it was made by TI.

    Tom

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