7 Feb
2014
7 Feb
'14
6:47 a.m.
On Fri, 7 Feb 2014, David Gesswein wrote:
On Wed, Feb 05, 2014 at 07:27:49AM -0500, Steven
Hirsch wrote:
>
> The immediate problem I'm facing is how to replace the IMI drives in
> my Corvus flat-cable systems. They are dropping left and right, but
> something about the interface scheme prevents it from working with
> anything other than the IMI units. Seagates will go through the
> motions but don't verify, acting as if they have not actually been
> formatted.
What drive model/interface does that use? I did a
little searching and
some IMI units use a non ST506 interface so without changes my unit can't
deal with them. The IMI 77xx are neat looking drives.
Corvus used the IMI 5006, 5012 and 5021H depending on the storage
capacity. From everything I can see, these are (or should be) plain
vanilla MFM drives. However, when I substituted a known-good Seagate
drive with equivalent geometry it refused to actually work. As I
mentioned in my original post, it goes through the motions of formatting
(steps through tracks for a decent amount of time) but then immediately
fails verification. I'm guessing there's a timing descrepancy or some
behavioral difference behind this.
The drive controller is also an IMI product that is not based on a
dedicated HDC chip. It's uses a Z80 and a bunch of peripheral logic,
probably a proprietary encoding scheme.
The more I think about this, the more I think they've taken some pains to
ensure it will only work with IMI drives - maybe some sort of special
operational mode?
Steve
--