9 Apr
2007
9 Apr
'07
3:44 a.m.
Jules Richardson wrote:
Actually, I wondered this the other day; ESDI got a
lot bigger (around
600MB I think) but IIRC was pretty much the same interface. So quite
what limited the capacity of ST412 drives I'm not sure. I believe that
cylinder seeking was done by a sequence of single steps (rather than
asking the drive: "seek to this cylinder"), so there's probably an
upper limit in the ST412 spec of how fast step pulses can be sent (and
beyond a certain size a drive will either become slow as mole-asses,
or some other timeout will come into play :-)
Jerome Fine replies:
I have a few 1.2 GB ESDI Hitachi drives which don't work
quite properly (they are slow on reading), but are very
nice for backups. I think that the sector size is a bit
small for what the Sigma RQD11-EC ESDI controller needs.
These are on my PDP-11/83. The smaller version Hitachi
ESDI drives of 600 MB were just great, as were XT8670E
drives from Maxtor. All of these drives are 5 1/4" FH.
I also used the 1.2 GB ESDI Hitachi drives on my PC under
W95 for a few years where the sector size did not seem to
be a problem on a Pentium 166 MHz system. I forget which
controller I used.
Sincerely yours,
Jerome Fine
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