22 Dec
2007
22 Dec
'07
4:54 p.m.
Subject: 5.25 drive with sector output
From: dwight elvey <dkelvey at hotmail.com>
Date: Sat, 22 Dec 2007 09:43:43 -0800
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Hi
Were there any 5.25 drive made with sector pulse output?
I'm working on a controller for my Polymorphic. I have not
software to run the board so I'm decoding the Z80 code
that runs in its firmware.
Yes, every one made. Sector pulse is the same ass index
on 5.25" drives. aqn example controller that uses that is the
NorthStart MDS.
I see that one of the signals from the drive is the
sector
signal. I know that the SA801 could be configured for
32/16/8 sectors and produce a sector output signal.
Still requires hard sector media.
In any case, the code seems to be looking for the
sector
signal at one point.
The next question is, do the older drives have a filter on
them such that they would not output the index along with
the sector pulse?
No.. But some of the old 8" had the index on the inner radius
and the hard sector holes at the outer radius making for two
seperate signals.
Allison
The drive I'm planning on using is an old Qume
drive with
a IBM lable on the front. It is a QUMETRAK 142. It is
good to work on because it is all descrete parts and
TTL ( some analog IC's as well ). Still, if they have a
filter on the index, I should be able to modify it.
I only see one pot in that area of the board and I suspect
that it is for the pulse witdh of the index.
If there is no filter, I should be able to make an external
sector separator.
Dwight
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