RFC: Floppy reader/writer project

Ray Arachelian wrote: Ouch! :( The problem is, you'd have to modify the drive to do that. The read head amplifier on just about all floppy drives (certainly all modern drives) does some pulse-shaping on the signal as well. What you'd have to do is find the amplified signal, then bring it into the range an A/D controller would accept, and digitise it. You'll probably want at least 20 megasamples/second to get a good amount of resolution out of the data, and for a revolution time of a second, you're talking 20 megabytes of data per track (assuming you use an 8-bit converter). What you can do with the pulse-timed data is read it out, then look at it and analyse it based on the encoding rules. So you could throw away data pulses that are obviously too close to others, or adjust the timing window dynamically to compensate for motor speed variations. One of the ideas I had for the Ext I/O inputs was a motor tachometer/position detector that constantly tracks the instantaneous speed or position of the motor spindle. Then you can look at the data from that, and adjust the timing values to get rid of motor speed induced errors. After that, all you're left with is the comparatively small error from the clock source (usually the crystal). This sort of thing probably wouldn't be too hard to add to the average 3.5" or 5.25" disc drive... the hard part would be getting the encoder wheel exactly centred on the spindle hub. -- Phil. | (\_/) This is Bunny. Copy and paste Bunny classiccmp at philpem.me.uk | (='.'=) into your signature to help him gain http://www.philpem.me.uk/ | (")_(") world domination.