4 Jun
2011
4 Jun
'11
7:36 a.m.
On 03/06/11 22:04, Phill Harvey-Smith wrote:
On 03/06/2011 21:51, Philip Pemberton wrote:
> Someone has just donated an old ST506 hard drive to the DiscFerret
> project... This time, it's an Amstrad drive, with part number 40095/A
> "DRMD20A12A".
[...]
I have one of those, it was the first working hard
drive I had on my
PC-200. I believe it's a standard 615x4x17 type 2, 20MB drive, or that's
how I've always formatted it, I think it will also format up as a 32MB
if formatted RLL.
Whatever it is, it doesn't have that many cylinders. The head stepper is
a 0.9deg/step thing, and the circuitry appears to single-step it. After
~380 steps, the flag on the motor shaft longer moves.
It's starting to look like this thing is a Type 01 or 23. But a 3.5in
half-height ST506 drive with a 10MB MFM capacity?! That seems too
strange to be true...
For bonus points, read_winchester is producing 130K of acquisition data
per track, and a rotation speed measurement of about 3550RPM. So the
data density is (in theory at least) roughly twice what the CDC MFM
drive produces.
Hmm.
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/