3.5" floppy drive question(s)

[Mr Ian Primus]

--- On Sun, 10/12/08, Chuck Guzis <cclist at sydex.com> wrote:
> > readable). Didn't even need to drill holes in the
> disks to 'upgrade'
> > them. Of course, these days, I find myself taping over
> the holes in
> > disks, since DD media is hard to find. 
> 
> At one time, diskette "punchers" were a popular
> item at computer swap 
> meets.  The price differential between HD and DD media at
> one point 
> was substantial. 

I remember seeing the punchers, but I never had one. I just used a hand drill, and drilled them one at a time. I also had a couple that I had needed to convert at the computer lab at school - which I did by cutting that corner off the disk with a paper cutter...
  
> > I've made high density 5 1/4" drives into 80
> track double density
> > (720K) drives by cutting the trace on the board that
> leads to pin 2,
> > and tying it to ground. This forces the drive into DD
> recording. 
> 
> You're leaving something out here.  While that forces
> the drive into 
> DD recording mode, the spindle speed doesn't change
> unless the drive 
> is also jumpered for "dual-speed" 300/360 mode. 
> So there can be a 
> real difference between a "fixed" drive and a
> genuine 720K DSQD 
> drive.

You're right. I am leaving something out. I also changed a jumper on the drive to do that. And, on one drive, I had to mess with the wiring of the spindle motor. Thanks for reminding me.

> Grab some documentation on early 1.44MB drives.  You could
> often 
> configure them for "auto sense" (the way most
> recent drives are by 
> default) or "remote sense" in which the status of
> the media sensor is 
> fed back to the host and the host selects the density via
> pin 2.  Or 
> do it the way the PS/2 did and ignore the media type
> completely.

Ah. that makes sense. I figured that there had to be some kind of function for that.


-Ian