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: > >>> 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. >
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
