31 Dec
2007
31 Dec
'07
12:46 a.m.
Hi,
I am restoring a Vector Graphic computer and would like to add a hard
disk drive. The controller only supports two kinds of hard disk
drives, the ST506 and ST412. The HD controller is hard coded to
support these DRIVES not just a compatible interface and relies on a
special signal present only in these actual drives.
What signal is that? I've looked at the schematics for thsoe (although
not recently) and I can't remember any extra signals on the connector.
Can this signal, if it exiasts, not be 'faked' on some other drive?
-tony
31 Dec
31 Dec
8:23 a.m.
From: ard at p850ug1.demon.co.uk
Hi Tony
I have the same question. The ST506 and ST412 were different
in the WrPrecomp signal being changed to a head select for
the ST412. I think he is looking at documents that state that he
needs a ST506/412 interface. This would be compatable with
just about any MFM drive made after the ST412.
There was a signal on some drives that came on the data cable.
I think it may have been a write protect but I don't recall
exactly what it was. The ST506 may have used this signal.
I'm not sure if this is what he is talking about.
I'd suspect things like step rate and number of heads would
be more important to him than anything else.
Dwight
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Hi,
I am restoring a Vector Graphic computer and would like to add a hard
disk drive. The controller only supports two kinds of hard disk
drives, the ST506 and ST412. The HD controller is hard coded to
support these DRIVES not just a compatible interface and relies on a
special signal present only in these actual drives.
What signal is that? I've looked at the schematics for thsoe (although
not recently) and I can't remember any extra signals on the connector.
Can this signal, if it exiasts, not be 'faked' on some other drive?
8:45 a.m.
On 31/12/2007 16:23, dwight elvey wrote:
> From: ard at p850ug1.demon.co.uk
> What signal is that? I've looked at the schematics for thsoe (although
> not recently) and I can't remember any extra signals on the connector.
I have the same question. The ST506 and ST412 were
different
in the WrPrecomp signal being changed to a head select for
the ST412. I think he is looking at documents that state that he
needs a ST506/412 interface. This would be compatable with
just about any MFM drive made after the ST412.
There was a signal on some drives that came on the data cable.
I think it may have been a write protect but I don't recall
exactly what it was. The ST506 may have used this signal.
I'm not sure if this is what he is talking about.
There's a "drive selected" signal, but I think most drives have that.
It's there because the 34-way control cable is daisy-chained but the
20-way data cable is radial, one per drive.
I'd suspect things like step rate and number of
heads would
be more important to him than anything else.
The other important difference between the ST506 signals and the ST412
was that the ST506 didn't support buffered seek; the timing of the step
signals had to be slow enough that the stepper motor could keep up. The
ST412 was the first drive that buffered the step signals, so they could
be sent rapidly, and virtually every hard drive after that did too.
--
Pete Peter Turnbull
Network Manager
University of York
9:22 a.m.
From: pete at dunnington.plus.com
---snip---
There was a signal on some drives that came on the data cable.
I think it may have been a write protect but I don't recall
exactly what it was. The ST506 may have used this signal.
I'm not sure if this is what he is talking about.
There's a "drive selected" signal, but I think most drives have that.
It's there because the 34-way control cable is daisy-chained but the
20-way data cable is radial, one per drive. I'd suspect things like step rate and number
of heads would
be more important to him than anything else.
The other important difference between the ST506 signals and the ST412
was that the ST506 didn't support buffered seek; the timing of the step
signals had to be slow enough that the stepper motor could keep up. The
ST412 was the first drive that buffered the step signals, so they could
be sent rapidly, and virtually every hard drive after that did too.
9:53 a.m.
On 31/12/2007 17:22, dwight elvey wrote:
This is important because many drives that had the
auto step, were
really slow using the fixed rate step. I had this problem getting
a ST251 to run on my Olivetti M20. The original drive had a fast step
rate of something like 6 ms. The ST251 wouldn't work faster than
10ms as I recall but the auto rate was much faster.
I remember a similar issue on one of my old machines. Some of those
hard drives stepped more slowly than many floppys! A genuine ST506 has
a 3ms step rate, while a genuine ST412 accepts seek pulses at 5-500
microsecond intervals (any slower than 0.5ms, and it assumes they're not
going to be buffered but then they do have to be *much* slower).
--
Pete Peter Turnbull
Network Manager
University of York
6201
days inactive
6201
days old
4 comments
3 participants
participants (3)
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ard＠p850ug1.demon.co.uk -
dkelvey＠hotmail.com -
pete＠dunnington.plus.com