8" Floppy Drives

The Applesauce (rev 2 and higher) works with most 8“ floppy drives that conform to the Shugart 50 pin interface standard. A 50 pin to 34 pin adapter is required to connect drives to the Applesauce's PC connector.

Most 8” drives require an additional power supply for +5VDC, +24VDC, and sometimes 120/240VAC.

Two options exist: the FDADAP, and custom cables.

The D Bit FDADAP board is the easier of the two, and also automatically provides the TG43 signal necessary for some drives to write successfully. It also has a convenient LED display of the current track being accessed.

The FDADAP needs +5V, and can be Applesauce-powered via the PC Drive Cable Kit.

Connect a 34-pin IDC cable between the Applesauce and the “PC FDC” connector. Then, connect a 50-pin cable between the 8“ floppy drive and the “8 INCH” connector. Recommended parts for constructing a 50-pin to 50-pin edge connector cable are:

• 3M 3415-0001 (50-pin edge connector)
• 3M 89150-0103 (50-pin IDC connector)
• 3M 3439-2 (edge connector polarizing key, optional)

The 50-pin cable can be made very short, if desired. There is also a 3D-printable mounting bracket to attach the FDADAP to the back of a Shugart 850/851 drive.

Other similar adapter solutions are also available.

If you are only reading 8” disks, if you can confirm your drive does not require the TG43 signal for writing, or if you are prepared to manually toggle the TG43 line yourself while writing a disk, it is possible to build an adapter cable yourself.

One approach involves using scavenged components to adapt the 8“ drive's 50-signal edge connector to a standard 5.25” 34-signal edge connector, using wire wrap to map the signals to the correct lines. If using this approach with the Applesauce, and writing of 8“ disks is desired, the “Manual TG43 control” option will be necessary.

The average single 8” drive requires at least +5V @ 1A, +24V @ 1-2A, and may also require -5V @ 100mA. The most common connector to supply these voltages is a 6-pin AMP Mate-N-Lok connector P/N 1-480270-0, utilizing pins P/N 60619-1 (qty. 6).

Some drives (such as the Shugart 850/851 and QumeTrak 842) also require 120VAC or 240VAC for the spindle motor, which runs continuously. For the mentioned drive, the connector is a 3-pin AMP P/N 1-480700-0 with pins 350550-1 (qty. 3). Some more modern drives do not require 120VAC/240VAC at all.

The D Bit FDDC “is a DC-DC converter which boosts/negates the voltages from a PC power supply to those needed by most 8” floppy drives. It can attach to an IDE power connector on a PC's power supply that has sufficient capacity to power both the PC and an 8“ drive”.

Care must be taken to ensure the +5V supply to the drive is well regulated - otherwise, damage to the Applesauce may occur.

TODO(vtgearhead): Jumpers and photo.

Manuals available.

Details (specs, jumpers, etc.)

The 842 has two power inputs:

• a 6-pin mate-n-lock which is 5 VDC, 24 VDC, ?-12 VDC?, and a common ground
• a 3-pin molex-like connector with 120/240 VAC, depending on region. (Check the ratings on the spindle motor.)

The 3-pin connector powers the spindle motor which runs all the time. For running with the Applesauce, one can make a power cord that plugs into the wall.

Verify the rubber grommets on the solenoids are in good order. Gummy or dry grommets can prevent the head load from engaging or disengaging. Bad grommets can also be a problem on the drive door lock.

Details (specs, jumpers, etc.)

Jumper options on this drive are extensive. Be sure to review all settings if experiencing problems.

It can be convenient to configure the drive to not lock the drive door when accessing, especially when dealing with damaged, flaky, or moldy media.

Use of these drives is strongly discouraged. The cone/clamp hub mechanism applies too great of a clamping force, and can tear the hub out of the diskette, ruining the media. You have been warned!