PDA

View Full Version : 3.5" Floppy to IBM Clone PC



Macmaster2000
April 8th, 2016, 07:43 AM
Recently I got a Compaq Portable, but one of the 5.25 drives is bad, is there a way I can add a 3.5in drive to the system? I have seen some floppy controllers on eBay, but I don't know if they support 3.5 in, and some of them have 16bit ISA slots, which is no use to me and my 8bit slots.
Is there a way to make a 3.5in drive work on the existing controller? I couldn't find any information online.

fs5500
April 8th, 2016, 07:52 AM
I know "Compaq Portable" (CPU:8088 based) supports 5.25" (360KB).

http://www.vcfed.org/forum/showthread.php?46277-Replacing-5-25-drives-with-3-5-drives-on-a-Compaq-Portable-I

According to the thread, Compaq Portable I seems to support 3.5" drive as 720KB.

Of course it depends on main BIOS to support 3.5" drive.

glitch
April 8th, 2016, 08:00 AM
You can get an add-in controller with its own BIOS that will let you use 1.44 MB 3.5" drives on machines that lack BIOS support. I have a number of them that work with anything from the original IBM 5150 PC onward. IIRC there was an XT-FDC project a few years back, but I don't remember if this went anywhere. PM me if you'd be interested in a vintage floppy controller that'll work with your system.

As mentioned, you can almost always use a 1.44 MB 3.5" floppy in place of a 5.25" 360 KB floppy with old PC compatibles. You do need to use 720 KB 3.5" diskettes with it though.

krebizfan
April 8th, 2016, 08:01 AM
Yes, you can hook up a 3.5" drive to the controller. It will only work in double density mode (720kB) but most high density drives do downshift automatically. You may need to pick up a new cable or adapter and you will probably want a face plate filler to keep from filling the innards with dust.

I think there was an old thread here about it. Quick search shows: http://www.vcfed.org/forum/showthread.php?46277-Replacing-5-25-drives-with-3-5-drives-on-a-Compaq-Portable-I

modem7
April 8th, 2016, 03:18 PM
According to the thread, Compaq Portable I seems to support 3.5" drive as 720KB.

As mentioned, you can almost always use a 1.44 MB 3.5" floppy in place of a 5.25" 360 KB floppy with old PC compatibles. You do need to use 720 KB 3.5" diskettes with it though.

Yes, you can hook up a 3.5" drive to the controller. It will only work in double density mode (720kB) but most high density drives do downshift automatically.
I will only add that if the Compaq Portable situation is the same as the IBM 5150/5160 situation, then the ability to format a 720K diskette will require some additional configuration. See [here (http://www.minuszerodegrees.net/5150_5160/720k/5150_5160_720k_driversys.htm)].

Macmaster2000
April 9th, 2016, 03:58 PM
Anyone have an idea on how hard and expensive to add a hard disk to this machine? Or should I make another thread?

trr94001
April 9th, 2016, 08:21 PM
I have a Compaq Plus I took to college. It's just the Portable with an MFM hard drive so you should be able to add either a similar, period drive or an XTIDE based compact flash solution. Personally, I'd recommend the latter since you won't have to remove a floppy drive to do it and you won't have to deal with a balky old hard drive.

That said, I _think_ that early Portables, like early IBM 5150s, may need a bios upgrade to boot from a hard drive.