A2 5.25 Drives (19 Pin)
- 1 AppleDisk 5.25 (A9M0107)
- 2 Apple UniDisk 5.25 (A9M0104)
- 3 Apple DuoDisk 5.25 (A9M0108)
- 4 Apple UniFile / DuoFile 5.25 (Unreleased)
- 5 Apple Uni/Duo Drive 'system'
- 6 IIc Plus, IIgs ROM 3, LC Slot //e Card & 5.25" Drives
- 7 20 Pin drives: Converting to 19 pin
- 8 Apple Disk ][ Converting to 19 pin. Addendum
AppleDisk 5.25 (A9M0107)
The Platinum colored AppleDisk 5.25 aka Apple 5.25 drive is the one universal solution for all Apple II systems and most clones/compatibles. Attached via either the AppleDisk 5.25" controller or SmartPort/Drive Port connectors. This drive is compatible across the entire line. Be sure the model number is A9M0107 as this drive is identical to the UniDisk 5.25" in styling, the case color is the difference. The UniDisk 5.25" is beige colored drive.
There are a few third party vendors who made a disk drive that was compatible with the AppleDisk 5.25", some of them are Applied Engineering and American Micro Research. Not all of their products would be, but the later model half height ones are and by this time it was seemingly the same drive that all the vendors were offering.
Apple UniDisk 5.25 (A9M0104)
The UniDisk 5.25" disk drive is compatible with all Apple II models except the ROM 03 IIgs, IIc Plus and LC //e Card. These require the AppleDisk 5.25 (A9M0107) or compatible drives.
Apple DuoDisk 5.25 (A9M0108)
The DuoDisk 5.25" disk drive is compatible with all Apple II models except the ROM 03 IIgs, IIc Plus and LC //e Card. These require the AppleDisk 5.25 or compatible drives. Using the DuoDisk with a //c will result in only Drive 1 ever being used as Drive 2 is not accessible since the //c is really using drive the first 5.25" drive on the drive port / daisy chain as it's second 5.25" drive.
Apple UniFile / DuoFile 5.25 (Unreleased)
The Apple UniFile and DuoFile were to be a storage solution based on the Apple FileWare system which utilized Apple's Twiggy Drive. The Twiggy drive is a 640K double sided drive with horizontally opposed head placement allowing both read/write heads to function simultaneously for more efficient throughput.
Apple Uni/Duo Drive 'system'
The Uni/Duo drive 'system' was thought out to be compatible with any Apple computer system shipping by utilizing all the same connector on the back of the drive for both single and double drive units. This is evidenced by the DuoDisk 5.25" having the 25 pin connector, the Apple /// Plus having the same 25 pin connector and the original concept UniDisk 5.25" each having two 25 pin connectors. As well, the external FileWare drives were to have the 25 pin connector. This way you could use any floppy drive with any system that a cable was provided for.
DB-19 Connector version. Drives that fall into this category are the Apple DuoDisk, Apple UniDisk 5.25", AppleDisk 5.25", any converted 20 Pin drives and many drives offered by other vendors with a DB 19 cable and daisy chain pass through port. The DuoDisk does not offer the pass through port because it is a 2 drive unit and since the 5.25" is always the last device on a drive chain, it is not needed.
IIc Plus, IIgs ROM 3, LC Slot //e Card & 5.25" Drives
Smartport drive information & why some 5.25" drives don't work.
The reason drives may not work with the IIgs ROM 03, IIc Plus or Macintosh LC //e emulator card is because around the introduction of the Apple IIc Plus, Apple changed the Smartport protocol to where each device hooked to it, (be it 5.25" drive, 3.5" drive or a Smartport compatible hard disk) needs an ID Byte. The UniDisk 5.25", DuoDisk and most 3rd party drives DO NOT CONTAIN this needed ID Byte rendering such drives unusable with the newer Smartport protocol.
The difference is due to the way Apple implemented the Write Protect circuit on their own disk drives. The Apple design integrates the Stepper Motor Phase 2 in the write protect status detection where as many third party drive manufactures used a simple ground to complete the circuit. Incompatible drives on these models will just spin at startup, the recalibration will not take place. However placing a disk into the drive enough to pass the Write Protect switch, or a write protected disk, before turning on the computer will allow the drive to boot. Thus it is possible to use incompatible third party drives with the IIc Plus or ROM 3 in a constant write protected state.
20 Pin drives: Converting to 19 pin
The 20 Pin Disk ][, or compatible, when combined with a 19 pin adapter or replacement cable, can be used with a //c or IIgs ROM 00 or 01 via the Smart Port/Drive Port connector, or at the end of the daisy chain as the last 5.25"/Last device on the chain. When it is used with the //c it is assigned to Slot 6, Drive 2. When used with a IIgs it will be Slot 6, Drive 1 or 2 depending on the position it is connected on the Daisy Chain.
Apple Disk ][ Converting to 19 pin. Addendum
In some configurations the Apple Disk ][ Drive also works when the cable is changed to a 19 pin cable. This is dependent on variations of the Analog Card in the Disk ][ and varies widely. YMMV.