RL02K Pack Reliability/Characteristics

E. Groenenberg quapla at xs4all.nl
Wed Apr 1 01:27:21 CDT 2015

>> This sounds strange. Are you sure you are not just fiddling with the
>> head here? A head switch will taste like a seek, but it might actually
>> not move you as you would expect...
>>        Johnny
> The head bit is not adjacent to the cylinder offset field in the command
> word, and I've verified with the logic analyzer that my intended commands
> are being sent.  Actually, it's ironic because the head alignment on my
> drive is near perfect.  I can switch heads and I am on the same track,
> opposite side, every time.
> Now I'm almost certain this seeking problem has something to do with the
> logic on the drive because so far, the drive only ever mis-seeks when
> trying to land on an odd numbered track.  The controller re-issues the
> seek, but there's a time penalty.
> A normal single track seek on my drive takes ~12ms.  Most bad seeks to odd
> numbered tracks tend to take me an additional track beyond what I wanted,
> requiring another ~12ms seek to get back on track.  Not that performance
> is a key factor here, but I'd like to understand why this is happening.
> Christopher

Could this odd behavior have something to do with the revision of the
internal RL02 controller board? From what I remember, there a 3 versions
of this board.


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