13 Apr
2006
13 Apr
'06
4:19 p.m.
John Foust wrote:
At 03:07 PM 4/13/2006, Tony Duell wrote:
<snip>
A friend recorded and played-back perhaps
ten or fifteen seconds of video on a (I think) 40 meg drive.
It was purely analog, not digital. (Amigas were early users
of IDE drives, so it might've been IDE, although that doesn't
really matter in this case, does it?)
I'm not aware of an analog way to access IDE, the interface is similar
to SCSI. The
SMD interface, Trident, or older 5440 drives had interfaces that
minicomputers had
to supply data separators and encoders for, and were able to record in
an "analog"
mode.
The object of the IDE and SCSI, and the earlier unsuccessful ANSI and
maybe SA1000
and SA4000 were to move the data separator and so forth into the drive.
The main
thing that was analog on any of these is that one could design an
interface which recorded
with different clock and data schemes, and could implement something
like PCM or
other phase modulation. The response was not really analog by any
means, but was
heavily tilted for digital, that is to get clear "true" and "false"
type
data to and
from the disk. If you had an interface to a media that
allowed for
analog level
responses, then you ran into problems with the signal moving up and down
with
less than desirable response, and therefore might get errors.
Hope this makes sense. I was involved in interfacing to a Western
Dynex, and
to some Trident and CDC drives, where other than mini computers were
using the media.
One of the earliest stop motion recorders used in broadcast used a
single drive and
a 5440 type head and positioner to record a few seconds of video, and could
be stopped and replayed easily. It used a different sort of interface
to get the
video to the media than a normal disk drive did, but the ones I saw
actually used
the same heads and media and positioners that our drives did (10mb capacity
on 4 heads, or 2.5mb / head).
Jim