18 Aug
2015
18 Aug
'15
6:08 a.m.
On 8/17/2015 1:51 PM, Rich Alderson wrote:
From: Jay Jaeger
Sent: Sunday, August 16, 2015 3:18 PM
On 8/16/2015 9:00 AM, Michael Thompson wrote:
Well, not exactly a wired or, per my TU56 manual, but yeah point taken.
At least on the TU56 the head windings are connected in series,
resulting in the *analog* sum. (A wired or didn't quite make sense to
me - it wouldn't really be redundant, so I looked it up).
But it brings me back to my original point - I don't see how this could
be the drive unless the block number in question always involves a
particular channel on the tape.
JRJ
> We did a lot more debugging on the TC12
LINCtape controller.
Second gut hunch is that it would be hard to see
how the drive could
cause this UNLESS the TC12 uses one side of the redundant tape channels
in one direction, and the other side in the other direction.
Not possible. The *drive* wire-ORs the redundant channels, before the
data goes into (or after it comes out of) the controller. *That's* the
redundancy. When reading in the reverse direction, only the mark tracks
on a DECtape read the same way backwards as forwards; LINCtape uses a
different set of markers.