[Coco] Tandy Controllers

[Steve Ostrom]

How many different disk drive controllers did Radio Shack/Tandy release?  I 
think there are at least 5.  Two long ones numbered 26-3022 and 26-3029, as 
well as three short ones numbered 26-3129 (FD500), 26-3131 (FD501) and 
26-3133 (FD502).  Were there significant differences between each of these? 
Were they renumbered because of ROM differences?  I think the long vs. short 
had different power requirements (12v vs. 5 v?).

-- Steve --