[Coco] Coco FDC

[Warren Hoslet]

>Does anyone know where I may find a listing of the Coco Floppy Disk
>Controllers, their Tandy Part Number (26-????) and model numbers (FD500,
>501, etc) and description (what controller chip, maybe a schematic
>and/or service/technical manual)?
>Thanks.
>
>/Chester
>
-
Here is summary in the order they were produced:

26-3022
Large Case
WD1793 FDC
Disk Basic 1.0 (24-pin ROM)
Requires 12V supply
Schematic: 
ftp://maltedmedia.com/coco/MANUALS0/TANDY/HARDWARE/FLOPPY/WD1793_12V.gif

26-3029
Large Case
WD1793 or MB8877x FDC
Disk Basic 1.1 (24-pin ROM)
Schematic: 
ftp://maltedmedia.com/coco/MANUALS0/TANDY/HARDWARE/FLOPPY/WD1793_5V.gif

26-3129 and FD-500
Large Case
WD1773 FDC
Disk Basic 1.1 (24-pin ROM)
Schematic: ???

FD-501 (26-????)
Small Case
WD1773 FDC
Disk Basic 1.1 (24-pin ROM)
Schematic: 
ftp://maltedmedia.com/coco/MANUALS0/TANDY/HARDWARE/FLOPPY/WD1773.gif

FD-502 (26-????)
Small Case
WD1773 FDC
Disk Basic 1.1 (28-pin ROM)
Schematic: ???

The FD-501 and FD-502 are mostly the same design. The FD-501 has gold 
contacts. The FD-502 has buffered control lines on the floppy connector. The 
FD-502 is the only controller that uses a 28-pin socket for the ROM and has 
the FDC chip soldered directly to the board.

- Warren