PDP-12 Restoration at the RICM
RichA at LivingComputerMuseum.org
Mon Aug 17 13:51:11 CDT 2015
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.
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134
mailto:RichA at LivingComputerMuseum.org
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