Apple IIe 3.5 inch FDD

From: Adam Goldman <>
Date: Tue Sep 23 19:40:44 2003

SmartPort 3.5" drives aren't too hard to come by, but I believe the IIe
can't use them, and requires UniDisk 3.5" drives instead.

For technical information I would start with Apple's old Tech Notes,
which are now available on the web. Some of Apple's Technical Reference
Manuals might also help.

Although DOS 3.3 can't support 3.5" drives out of the box, there are a
number of hacks to add this capability (I think one of them was called

To use a standard Shugart-interface 3.5" drive to read and write GCR
format floppies on the Apple, you'd need to implement the whole disk
controller from scratch. The Apple 3.5" drives had the controller inside
the drive, like an IDE or SCSI hard drive does; you'd need to reimplement
it. Much easier to just buy one :-). It _is_ possible to use a standard
drive mech, though. To deal with the fact that the mech isn't designed
for ZBR, you simply change the controller's clock speed as you seek.

The next step down in terms of difficulty is to take an off-the-shelf
NEC 765 based floppy controller, interface it to the Apple with a bit of
glue logic, and write a ROM that talks to it. This means you'd be
writing in MFM format, incompatible with real Apple drives.

If you want to be really nasty, you could consider that the Apple 5.25"
disk interface and the Shugart interface both are at the level of flux
transitions and motor steps... The circuitry to make a Shugart interface
3.5" drive look like an Apple 5.25" drive would not be too complicated.
You'd get 280K per 3.5" disk and the disks would be in a format totally
incompatible with everything.

Or you could just buy some 5.25" disks.

-- Adam
Received on Tue Sep 23 2003 - 19:40:44 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:36:26 BST