18 May
2006
18 May
'06
7:13 a.m.
Hi Chuck
It definitely doesn't like stepping at around 2 to 2.5 ms someplace.
I send the value 8 to the controller that is suppose to be 4.0 ms and
that works fine.
I don't know how a buffered seek would work on a MFM drive?
Are you saying that it should take in what ever step pulses I send it
and step at 8ms, regardless of what I send.
That doesn't seem to be the case with my drive. I is definitely stepping
at the rate I give it with a seek or restore command.
I hope I'm not overdoing it too much with the 4.0ms. The stepper
is right on the edge of quieting down at that rate. Similar to the
optimizer programs that set the step rate for the floppies. It
is right below the resonent speed. At 8.0ms it is really harsh sounding.
Dwight
From: "Chuck Guzis" <cclist at
sydex.com>
Reply-To: "General Discussion: On-Topic and Off-Topic
Posts"<cctalk at classiccmp.org>
To: cctalk at classiccmp.org
Subject: Re: Olivetti M20
Date: Wed, 17 May 2006 22:24:54 -0700
On 5/17/2006 at 9:55 PM dwight elvey wrote:
I still have some issues but all have work
arounds.
1. The BIOS sets the step rate too fast for the ST251. It
seems to be around 2.5ms. I found the ST251 doesn't
like more than 3ms. I wrote a program that I put on my boot
floppy that sets it to 4.0ms. Does anyone know the correct
step rate for the st251? I'll have to hack the BIOS some
day to fix this.
Dwight, the ST-251 has a buffered seek, so you should be able to fire out
seek pulses at 100 usec intervals and wait for SEEK COMPLETE. The
single-track seek time on the ST-251 is specified at 8 msec, with maximum
seek (621 cylinders) at 70 msec. I suppose you could treat it like an
ST506 and use 3msec, however.
Cheers,
Chuck