On 03/13/2016 03:12 PM, Chuck Guzis wrote:
On 03/13/2016 12:38 PM, Jules Richardson wrote:
These 3MB ones were definitely Olivetti - this was from an ex-Acorn
employee who worked on the drive project. 3MB to 20MB seems a big
jump - but it makes me wonder if they were working with drives that
had three surfaces masked out due to manufacturing defects; one
surface would be 5MB, and going from 3MB per surface in a
pre-production drive to 5MB in
Do you have a part number for the Olivetti drive?
No, unfortunately not, and the official service manual only mentions 10MB
and 30MB drives (neither of which were Olivetti parts).
I think that taking a
10MB drive and downgrading it to a 3MB one wouldn't be a paying venture.
AIUI, Olivetti only shipped these 3MB drives to Acorn while they were
testing their Winchester unit - Acorn never used them elsewhere. I am
curious if they ever saw production though.
Assuming for the moment that there were completely disabled surfaces
involved due to too many defects (i.e. that this was a 2-platter drive with
only one or maybe two active surfaces and the rest mapped out by the drive
firmware), do you know how common a practice that was in the early days of
ST506/412-type drives?
I've heard various stories of it happening much later with more modern IDE
drives in the multi-GB range (e.g. a 20GB drive might be a 40GB
single-platter drive with one surface that had completely failed QC), but I
don't know if it was ever done in the ST506/412 era.
Jules
