[sebhc] hard sector substitute

Dave Dunfield dave04a at dunfield.com
Sun Jul 11 20:19:18 CDT 2004

>I've been thinking about this. What I thought about was modifying an old 
>diskette drive to punch the holes automatically. It would have to be 
>modified to remove part of the drive where the index sensor is located. 
>A slideable pice could be built that contains both an index hole sensor 
>and a hole punch. A solenoid (or whatever) could move the index sensor 
>so that it could sense the hole in the diskette. If there were a stepper 
>motor used to rotate the disk, a Basic Stamp could rotate the diskette 
>until the hole is sensed. This would be the 0 degree position. The 
>slideable punch could then be positioned over the existing hole in the 
>diskette and the jacket. The stepper motor could then be rotated 18 
>degrees and the first new hole punched. Next, the stepper motor could 
>rotate the diskette 36 degrees (repeating this ten more times) to punch 
>the remaining sector holes. A solenoid or something could be used to 
>operate the hole punch. VIOLA!   A new hard sector diskette made from an 
>existing soft sector diskette.
>The difficult part would be to make the slideable index sensor / hole 
>punch device. It would have to be thick enough and with a slot into 
>which the diskette jacket could fit.
>Any new thoughts?

Hi Carroll,

I've had similar ideas - remove the drive motor (or just don't power it
for direct-drive drive) and implement a stepper motor which gives accurate
positioning of the media.

You might be able to get away without having to move the sensor and hole
punch if you make the punch retract far enough, and sense the hole at an
angle - I think it would be simpler to just line up the hole before
inserting the disk in the drive - with a stepper drive, the index hole will
NOT move as you close the drive lever. Then it's just a matter of
'x' steps (Index to first hole distance), Punch, 'y' steps (hole to hole
distance), Punch, repeat until at last hole.

I'd have built one by now, but I have not been able to fashion a decent
punch yet. Any ideas?

dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.

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