FC5025 USB 5.25 floppy controller - first report  Tony Duell ard
at p850ug1.demon.co.uk Wed Feb 24 14:58:07 CST 2010  > Fair
enough :-).  The TTL chips of which you speak are bidi bus  >
transceivers, correct?  Would you use the R/W line to switch
directions,  > or is there other magic involved?  No, they're
just palin unidirectional buffers, open collector outputs.  Look
up the 7406 (inverting) and 7407 (non inverting) data sheets. I
am  sure they're on the web somewhere (I've not checked, I've
got several  paper TTL data books here).  The lines to a floppy
dirve do not reverse direction. Eachg signal is  either
controller to drive (for example, the drive select lines, write
data, write gate, step, direction, etc) or drive to controller
(e.g. read  data, index, track 0, etc).   You need to buffer the
signals from controller to drive, certainly. I'd  use a circuit
like this for each signal -- and put it close to the  controller
board. :                                  / 1k
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