[sebhc] hard sector substitute

Dwight K. Elvey dwight.elvey at amd.com
Mon Jun 28 19:39:34 CDT 2004

 Steve Thatcher and I talked about this a month ago. It
seems like it would be a relatively easy project. One
could do it with one of those PLL chips and a couple 555's
from an analog side or just use a PIC to create the pulses.
 It saves having to find hard sectored disks. It does require
that the drive be in good shape. The rotational speed
has to be nice and constant. I don't know what the
tolerance would be but I suspect it is within the
range that most drives would work fine.
 As far as drives go, I'd suspect that a H17 would drive
either a 720K or a 1.44M. Of course, it wouldn't be
any faster. That would require a faster processor.
You'd need to deal with any rotational rate change but
I'm not sure what these are for these drives.
As it is now, it is just about as fast as it needs to
be between writing bytes.
 I should note that my Z80 machine includes the jumper
modifications to do double sided disk. If anyone wants
this information, I can make some notes.

>From: "Jack Rubin" <jack.rubin at ameritech.net>
>> In the days when I was active with my H89, I would often use 
>> a 3.5 inch drive with my H37 controller. It was much more 
>> convenient than the 5.25 inch disks. 
>What did it take to run 3.5 drives with the H37? What drives did you use
>- did you need 720K or could you use 1.4M units?
>> that the floppy was hard sectored. This could be done with 
>> both 5.12 and 3.5 inch disks - you would use soft sector 
>> diskettes with the H17.
>> Two questions:
>> 1. Has anyone already done this?
>> 2. Perhaps more important - Is anyone interested?
>1) not that I'm aware of
>2) I expect that there would be a (long?) line of people willing to buy
>a PCExpress board that would let them hook up 3.5 drives to an H17! I
>can think of at least 6 anyway (I'd be good for a couple, for sure).
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