UniDisk ///.5 Driver for Apple ///

This is the elusive Apple /// driver file for Apple’s UniDisk 3.5″ floppy drive.  It’s a non-bootable disk image that contains only the SOS.DRIVER file that you’ll need to build into your system with the SCP.

This driver will allow your Apple /// to use 800K 3.5″ floppies.  You’ll also need a Liron card and a UniDisk 3.5 (model #A2M2053, the one with its own 65C02 chip).  These drives are rather uncommon and the Liron controllers, while not as infrequently spotted as the drives, aren’t exactly everyday items either.  But if you can find the individual parts, the drive/card/driver combo adds quite a bit of storage to your beloved Sara.

This is version 1.1 of the driver, which was developed for ON THREE by Rob Turner.  I don’t have the accompanying manual ON THREE distributed with the disk, but I’d be happy to scan and post it if anyone wants to lend or sell me one.  I also welcome “donated” scans, If you’d prefer to digitize your own and let me host the PDF you create.

Download the zipped disk image here: UniDisk ///.5 Driver for Apple /// (3K zip file)

* Note: If you’re planning to use this set up for more than just a quick “ooh neat, look what I did with my Apple ///!” one-time run, you should probably be aware of the following driver technical info:

#: 81372 S7/Apple ///
17-Oct-86 22:41:29
Sb: UniDisk 3.5
Fm: Robert L. Consorti 75056,2110
To: All Uni-Folks

All UniDisk 3.5 Users:

Do not set a recording file in Access /// or any other comm. program to point to a file on a UniDisk. In order to get the UniDisk to run on the ///, very time-sensitive code is used. It’s so time sensitive it has to disable interrupts during the time it’s sending info. to the drive.

If you try typing into the type-ahead buffer during an IO to or from the UniDisk about 1 out of 10 characters will be lost and not placed into the type-ahead buffer. This presents a much bigger problem it you try to send a recording file to the UniDisk. Because the .RS232 driver collects it’s characters via interrupts, just like the keyboard, certain characters are lost. This can be a big problem if the data that is lost is a controlling byte to the driver. In these instances it is possible to have the driver hang-up.

Because of this, please don’t use the UniDisk as a recording file. Try using the internal drive as the recording spot.

– Bob Consorti –


#: 81481 S7/Apple ///
18-Oct-86 15:01:10
Sb: #81360-ACCESS ///
Fm: Michael R. Schroeder 73717,3723
To: Frank W. Moore 74666,3660

Frank, Got the driver for the Unidisk from On Three. Page 28 of their manual states:

The drivers for the UniDisk 3.5 have to disable interrupts during the very loading a file to or from the Unidisk 3.5, you may sometimes lose a character that you type. There is no way around this. Sorry about the sloppy typing. Schroeder.

Apple2Online.com has a nice collection of UniDisk 3.5 technical notes compiled into a single PDF, which you can access here.

VintageMacWorld.com seems to have disappeared into the ether, but thanks to the magic of Archive.org, you can find their awesome Apple Floppy Drives page here, which contains some basic info and identification tips about the UniDisk 3.5, in case you’re not sure which drive you’re looking at.

IMG_0003