[Coco] 5 1/4" drive

[Christian Lesage]

Bill wrote:
> Refresh my memory, please. Can an 80 track 1.2M 5 1/4" drive be installed
> into an FD-502 case and work correctly? Will it act like a "standard" floppy
> drive using the stock chip in the controller?
>
> Thanks
>
>   
Let me clarify my previous answer: a 5.25" HD (1.2Mb) drive has a 300 
kbps data rate when operating in double-density mode (and a 500 kbps 
data rate when operating in high-density mode). The FD-502 needs a 250 
kbps data rate. This can be achieved on some 1.2Mb drives by reducing 
the RPM from 360 to 300 (jumper or mod). On the other hand, a 3.5" HD 
(1.44Mb) drive can be used because it spins at 300 RPM and therefore has 
a 250 kbps data rate when operating in double-density mode. However, it 
can be tricky to make a 3.5" drive behave like drive 0 because 
PC-compatible drives are always configured as drive 1 (in a PC, it's the 
cable that determines whether the drive is A: or B:). Sometimes, you 
have to disassemble the drive and move a tiny 0-ohm surface mount 
resistor on the PCB (maybe not all drives have such a jumper). Older 
drives may have "old-fashioned" jumpers, which facilitates this task. 
Please also note that AFAIK and unless you make a custom cable, a drive 
intended for a PC cannot be configured as drive 2 or 3 (it's either 0 or 1).

Christian