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Did they make serial or parrelel port PC floppy drives?

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mandarpatil

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May 27, 2020
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I've got 2 Compaq III's, one with a 3 inch drive and another with a 5.25 drive. I can easily transfer files to the one with the 3 inch drive but There's no way from what I can see to make a 5.25 1.2 MB boot disk for the other one. So bringing me to my question of if there's a way I can hook a external 5.25 to my 3 inch drive.

Any help would be great, thanks.
 
Hello,

When you refer to a 3" disk, please note that there IS such a thing as a 3" drive, my Amstrad PCW uses such, however are you maybe referring to the 3.5" standard PC type disk which is a quite different thing?

As for the 5.25, I assume you are aware that most PC type machines will boot quite happily from a 360k disk in a 5.25 (1.2Mb) drive, and once the system is loaded then a 1.2Mb disk can be used. Or do you not have ANY 5.25 boot disks? I might have a MSDOS 3.3 boot disk somewhere (360k format), but not a 3.2 as originally used by the Compaq?

Geoff
 
Oh, not answered the other part of your question

I assume you want to connect an external drive to the 3" (3.5" ?) machine so you can create a 5.25" boot disk, and/or copy data between the two machines?

There may well have been such drives, but more likely for the parallel port. The external ZIP disk system used this port, but needed a fairly sophisticated driver
to complete the load and assign a drive letter. If you manage to find a drive, make sure you get the software to go with it.

Far better, and more reliable to find access to a working machine with a 5.25 drive (i.e. BOTH a 5.25 and 3.5, one with a 5.25 and a 3" much more difficult).

Geoff
 
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There certainly are parallel port floppy drives--the Microsolutions Backpack drives are perhaps the best known--but there were others; I've got one from Rancho, for example. The only serial port drives that I've personally seen were replacements for paper tape--e.g. embroidery machines, CNC gear.

There are/were some P2/P3/P4 chipsets that use a LPC multi-IO southbridge chip mostly on laptops. One could configure the parallel port either as a printer port or as a floppy drive, but not both. When configured as a floppy drive, it is usable without special drivers, whereas the parallel-port add-on drives require a device driver.

That doesn't mean that the Backpack, for example, could not be used as a drive with, say, IMD, but that the code was never included. We sold a specially-configured Backpack drive with our own drivers that allowed customers to work with their 1.23 M 3.5" PLC disks. I believe I posted source code that showed how to get a BIOS interface to a Backpack drive here some years ago.
 
mandarpatil said:
I've got 2 Compaq III's, one with a 3 inch drive and another with a 5.25 drive. I can easily transfer files to the one with the 3 inch drive but There's no way from what I can see to make a 5.25 1.2 MB boot disk for the other one. So bringing me to my question of if there's a way I can hook a external 5.25 to my 3 inch drive.

Any help would be great, thanks.
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Yes, Laplink would be very useful.

For the benefit of OP, Laplink was originally produces for connecting PCs to laptops, and transferring files etc. It was originally DOS software, although later there were WinDoze versions. The package came with two cables, one for using Serial ports, the other for parallel ports, the latter was certainly faster, but if you're not copying Mbs, then the serial one would be fine, and the serial cable is easier to make yourself from info you can find on the web.

The software that needs to be running on both machines linked lets both machines see all the files on both machines, and copy files back and forth, indiv and in bulk, between the machines. There is an option that one machine can load the software onto the other thru the link, but I've never needed to use that. The one catch in your present situation is that you need to have booted both machines, so the first step still is to get the machine with the 5.25" drive booted. AFAIR.

If you're a 'purist', then you may want to use the 'correct' version of DOS on both machines, but I'd suggest you worry about that AFTER you've got the second machine running/accessible - ANY version of DOS will do initially.

Geoff
 
INTERLNK/SVR is another alternative. More of a client server option over a nullmodem or LapLink parallel cable.
 
You can attatch an external LS120 drive to a parallel port and use 3.5 HD disks in it. I have one on my slimeline Zenith 286.
 
DeltaDon said:
There's USB floppy drives and I'll guess a USB to RS232 adapter could turn it into a serial port drive.
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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.
 
tingo said:
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.
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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.
 
uh, yeah "a machine" I called that third piece. Perhaps I should have written "a computer" instead.
 
tingo said:
uh, yeah "a machine" I called that third piece. Perhaps I should have written "a computer" instead.
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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?
 
Those Backpack floppy drives work a charm like Chuck suggested. They just work in most scenarios. Great tool to have.
 
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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