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PS/2 FDD interface

P

per

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I have heard that some of you have attempted to make an adapter making it possible to use normal floppy disk drives on PS/2's. Since I may need to make an adapter like that (unless the FDD in my PS/2 actually works), I would like to know what pins to redirect where. I know it may go badly wrong if I get something wrong.

And another question; is the HDD an IDE drive, or something completely nonstandard?
 
Which model of PS/2 are you talking about? The hard drive interface that IBM used varied widely depending on the particular model: ranging from a proprietary interface in the low-end ISA models (25, 30, 30-286, etc.), to MFM, ESDI, and SCSI. I belive the only member of the PS/2 lineup which came with IDE was the oddball mini-desktop "PS/2 E", although aftermarket IDE controller cards may have been available. Also, your machine may have had parts swapped in from another model, so it is entirely possible to take a model that originally came with an MFM hard drive and then swap an ESDI hard drive (and controller card) into it.

As far as I know, the floppy drive interface is standard, but has the DC power supply voltage running through the ribbon cable, rather than through a separate power wire, and a proprietary card-edge connector is used. So you could use a standard floppy drive, but you could need to custom-wire both the interface cable and the power wire.
 
I am uncertain of weather you will be able to do this as the sizes for the floppy disks were not necessarily that which they are in modern computers. Rework on the case itself may be necessary to do so.
 
It's a standard Model 70, 386 version. The only difference as I can see when comparing to normal modern drives are that the mounting is different, and the connector.

And it's basically the connector I am asking about. Nonstandard 40-pin VS regular 36 pin.
 
Is there room for a PCB with edge connector and a 34 pin header between the PS/2 edge receptacle and a conventional 3.5" floppy? If so, it should be a fairly simple matter to create a PCB to work. Otherwise, it gets pretty messy.
 
Here are the PS/2 floppy drive pinouts:

http://ohlandl.ipv7.net/floppy/Floppy_Pinouts.html

The "40-pin card edge connector" version appears to be the same thing as a standard 34-pin floppy drive cable, with a few extra wires for +5 and +12 volts DC and an extra ground.

The model 70-386 has an ESDI hard drive controller built onto the motherboard (a.k.a. "planar" in PS/2-speak).
 
You might find the pin layout for modern drives here

You might find the pin layout for modern drives here

The layout for a lot of old and modern drive controllers are on this website, It may prove useful in retrofitting an old controller if it is on the expansion, if it is on the mainboard then you probably wont have to use this information.

http://stason.org/TULARC/pc/hard-disk-floppy-controllers/index.html

Here is the modern layout
http://www.interfacebus.com/PC_Floppy_Drive_PinOut.html


good luck!
 
vwestlife said:
...The model 70-386 has an ESDI hard drive controller built onto the motherboard (a.k.a. "planar" in PS/2-speak).
Click to expand...

Technically not correct. The IBM "DBA" (Direct Bus Attachment) ESDI connection is just a truncated 16-bit microchannel interface. All of the electronic components, including the controller, are on the drive chassis.

This is more evident with the Model 50Z (in a similiar case as the Model 70), because the DBA ESDI riser there can be plugged into another one of its microchannel slots...
 
The Model 70 386 uses ESDI HDs in the 60MB or so range (and special mounting brackets). I think I have a couple spare (would have to test them) and I am in the US so shipping would be pricey.

As far as floppy drives go, making an adapter sounds like a royal pain. The Model 70 has an edge connector for the floppy drive. Do you have a drive you are unsure if it works or are you missing one?

The PS/2 linup is a mess for floppy drives. You have different light layouts, different eject button thickness, edge or pin connectors, different mounting hardware, etc.
 
Unknown_K said:
The Model 70 386 uses ESDI HDs in the 60MB or so range...
Click to expand...

Yes, generally that smallest capacity when stock, but they did have up to the 160Mb DBA ESDI drives for later submodels. The entire range for DBA ESDI capacities was 30, 40, 60, 80, 120, and 160Mb. PS/2s with a DBA ESDI interface, including the Model 70, can run the associated drive of any capacity.
 
I have made an adapter for the 34 pin drives like those used in the Model P70-386 as seen in this thread:
http://www.vintage-computer.com/vcf...1-Using-Standard-floppy-disk-drives-in-PS-2-s
The tried to build an adapter of my own for the 40 pin card edge like that used in the model 70's but somehow I had a short from 5 volts
to ground and reasulted in me blowing my Motherboard up :( so I gave up on it. But I think it can be done. ;) Good luck in trying! and hope this may help some of you.
 
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