Apple 3.5 drive information There are two main types of Apple 3.5" Drive assemblies. There are actually 5 different variations, but two that matter which I refer to as 'Red' label and 'Black' label. The difference is in the logic board, in this image is the Red Label drive: http://www.apple2.org/images/DiskDrives&Related/PreLironCloseup.JPEG Looking at the area to the lower right side of the DRIVE, not the card under it, notice the solid area in the middle and connecting the pins in the middle of that 16 pin IC. O O O-O O O O O | \--------\ | SOLID AREA| Text Diagram | /--------/ O O O-O O O O O The Black Label drive does not not have this area filled in, but rather there are two traces running through there. That is the easiest thing thing to spot when just looking at the drive. The next thing is on the side of the drive is a serial number label, see http://www.apple2.org/35Drv/35Drv8.html for an example. The color of the *NUMBERS* is the drive type. = Red Label Drive Black Numbers = Black Label Drive Blue Numbers = Blue Label Drive. Blue?!?! Ok, another type. Blue is a 1.44 (FDHD) Drive. You can also tell a HD drive by the front, switches are three mini white or blue shafts, two on one side, one on the other. (Write Protect, disk inserted and HD or DD) The Nitty Gritty of all this is that over all, only drives of a certain color work in certain places. With reference to the Apple II, the only concern is the UniDisk 3.5. It requires a Black Label drive. For completeness, I'll list it all here. Red Label Drive Black Label Drive --------------- ----------------- AppleDisk 3.5 (Platinum) UniDisk 3.5 Apple IIc Plus Mac 512Ke Mac SE / Mac II Mac Plus Mac Plus * * You may find a Red Label drive in a Mac Plus, if so, you will also find with it a ribbon cable wita YELLOW stipe instead of the RED for pin 1. A yellow cable is required to use a Red Label drive in a Mac Plus or 512Ke. (Or 128/512 using the 800K As MFS only) The biggest difference in these two drive types is the eject/disk inserted detection. If you assemble a drive and you have the eject motor constantly going then you have the wrong drive type installed. Now, for a twist, this is not always the case, some times you will find a Black Label drive working where it should not be, two reasons, the board could have been changed. Properly identify the drive by the bottom instead) or the board has been modified. (You will see several components sleeved in clear plasic, soldered to various points on the logic board.) The Daisy Chain board in a UniDisk is for a UniDisk only, likewise, the board in the AppleDisk 3.5 and SuperDrive (FDHD) is for those drives only. For the AppleDisk (800K) and SuperDrive (FDHD) the daisy chain board is the same. You can make a 1.44 from your 800K drive by swapping the drive assembly. The The UniDisk daisy chain board is incapabale of 1.44. (MFM). Teh FDHD Drive Assembly will also work where an 800K drive (Red Label) was without any changes, but only as 800K unless controller hardware is present to support it. (In a pinch, you can use it if your up the creek with no drive)