[sebhc] hard sector substitute

Dave Dunfield dave04a at dunfield.com
Wed Jun 30 07:51:41 CDT 2004

At 08:14 30/06/2004 -0400, you wrote:
>Hi Dave, I was not contemplating modification of the drives and I also wanted to make the device work on any hard sector system. N* uses HS and not HM for example (I have both N* and H88 systems...).
>best regards, Steve Thatcher

Hi Steve,

Understood - my point is that I think it would work better if yo do
modify the drives - Perhaps this can be "faked" by externally gating
all the drive signals, however I anticipate problems in switching
to and from writing selected to "deselected", and you also have the
interesting "feature" that all drive select LED's would be on at
once! - but it may be feasable.

Here's another intesting idea - many drives have strobe disks for
adjusting the speed - this could be used to "read" the drive speed
optically, and therefore you could know exactly how often to
inject the extra pulses - you still have the sync problem with the
main index hole, but it would solve the problem of having to wait
for it twice to obtain exact drive speed. It would mean that your
adapter card would need a little sensor mounted under the drive

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

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