You'll need to spend a bit of time studying out
how the controller you're using handles the drive
select or even a cable select if it has separate
selection on the 34 and 50-conductor cables, and
whatever it does to manipulate the clock extraction
circuits to derive the appropriate clock for whatever
data rate you're wanting. BE CAREFUL! Some controllers
switch the clock frequency as they make whatever
assumptions they may make about the nature of what's on
each cable. In order to drive 3.5" diskettes, you need
to fool the controller and software into believing it's
talking to a drive on the 50-pin cable. Though the 8"
drives have only 77 tracks, they have the 360 rpm spin
rate and most other parameters in common with the little
teensy drives. If your controller switched the clock
assuming its top data rate will be 250 kbps, you may
have problems.
According to the docs, you have to tell the controller
which drive type it is talking to (bit 4 at I/O address
34 hex). Looking at the schematics, it sure looks like
it blindly shoots signals to both connectors. FDAT is
connected to pin 30 on the 34 pin header and pin 48 on
the 50 pin header. Hmmm... what's going on here? Pin 48
is SEP DATA, used with hard sectored drives isn't it?
Pin 50 is connected to FCLK as well.
What gives?