What's the rarest or most unusual computer-related item do you own?

[Chuck Guzis]

On 01/29/2017 01:55 AM, COURYHOUSE at aol.com wrote:
>  Honeywell Datamatic 1000  uses 3 inch wide tape
> we have a 3 inch very very heavy reel and  the 30 something  track  tape 
> drive head.... could this someday be the start of  the  ultimate  DIY tape 
> drive build and tape recover? 
>  
> see more  on this computer here... and  we have modules  for  this tube   
> computer we need to photo and more stuff to scan and add. 
> http://www.smecc.org/honeywell_datamatic_1000.htm

(Apology for the previous null message--hit the wrong button)

The tape used appears to be an early videotape formulation, but wider
than the initial 2 inch format used in Ampex's early machines.  It's a
sandwich affair with the magnetic oxide in the middle of two sheets of
mylar, so it should be pretty durable.

While there are 32 tracks on the tape, they're not used in parallel; a
given word is recorded serially on a track.  A good thing--deskewing 32
tracks would be a real issue for early electronics.    The curious thing
about the recording format is that blocks consisting of recorded words
are interlaced with respect to direction.  Thus, every other block is
recorded while moving in a forward direction, while the same holds for
the tape going in the reverse direction.  The general idea is to
minimize wasted space taken up by IRGs.

The tape units were buffered, such that a read could be initiated while
still processing data from a previous read operation.  The programmer
could take advantage of the fact that data from a read operation began
arriving some 200 clocks from read initiation.

All in all, a fascinating view into early design.

--Chuck