On Jan 27, 2010, at 10:17 AM, PeterH wrote:
On Jan 27, 2010, at 9:44 AM, Jeff Walther wrote:
I am trying to find out any SE used either of the below drives:
PRAIRIETEK 220A 20MB 2.5 inch 1/3HT IDE AT DISK DRIVE
PRAIRIETEK 220S 20MB 2.5 inch 1/3HT SCSI SE DISK DRIVE
The SE ... all of them ... used a SCSI 3.5* full-height ...
1-9/16* ... drive. Often Quantum, but possibly others. At that
time, Quantum made ... in Japan, by Mitsubishi ... probably the
best quality, lowest power SCSI drives.
Later, Quantum and others would standardize on 1* drives the so-
called *half-height* drives. This is the form factor which has been
used ever since, in SCSI, ATAPI and SATA.
Full height drives are 3" or a little more. This referred to the
original 5.25" drives. 1.6" drives are half height and 1" drives are
1/3 height, regardless of width (3.5" or 5.25").
Thus the original SE drives were 1/2 height, the smaller drives now
commonly used are 1/3 height.
At one time I had a half dozen 20 Mb drives that I think were all
made by MiniScribe. Rodime was another brand used. The MiniScribes
I had were all 1/2 height and used a stepper motor for the head
positioner.
As a note to anyone planning to format such drives, those early
drives had no buffer on the drive so the sectors were interleaved to
give the computer time to process the data before reading the next
sector. SEs used 2:1 interleaving and Pluses used 3:1 interleaving.
This is selected as an option
Clark Martin
Redwood City, California
Macintosh / Internet Consulting / Railfan
"I'm a designated driver on the Information Super Highway"
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