Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]

[Earl Baugh <earl.baugh@gmail.com>]

I thought the concern was about the fragility of the tape and the concern about running it thru a period reader. I was just thinking these two options would be safer on the tape.  That’s why I was suggesting them.  Just trying to be helpful .. all to familiar with the long project list :-) 

Earl 


Sent from my iPhone

> On Jan 15, 2020, at 2:12 AM, Jon Steinhart <jon@fourwinds.com> wrote:
> 
> Earl Baugh writes:
>> Why not build a variation of this with an Arduino?
>> https://www.instructables.com/id/DIY-Paper-TapePunch-Card-Maker-and-Reader/.
>> You could use cardboard rather than wood if it’s just a one time job. ( or scan
>> the tape into files and process digitally ?) 
>> 
>> Earl 
> 
> I thought that I said earlier that I had a paper tape reader here but don't
> remember much about it or if it ever worked.  If I didn't have a huge project
> list and it wasn't ski season I could hook it up to a pi.  More likely that
> I'll get to a computer museum sooner.
> 
> Just to keep this UNIX-related so that Warren doesn't get cranky, I believe
> that this reader came out of some sort of experimental telephone exchange
> in our group that was decommissioned.  Dave Weller was very supportive of my
> interests and somehow arranged for me to take much of it home as surplus
> equipment.  Kept me in 7400-series parts and Augat wire-wrap boards for a
> long time.  While there was no way that I could have kept the thing, I wish
> that I had the magnetic drum memory because it was so cool from an industrial
> art perspective.
> 
> Heinz may remember more about this than I do because he actually worked on
> this project, but our department developed what I believe was the first
> all-digital telephone exchange that used digital filtering (Hal Alles and
> Jim Kaiser were in the group).  I think that it had a pair of PDP-11/10s
> in it, and a bigger PDP-11 as a supervisory machine that ran UNIX.  I have
> vague memories of Heinz and Carl poring over huge C program listings.  I
> also remember that there was a bug in the long-distance code where it wasn't
> sending out the ST tone that ended up taking all of the key pulse senders in
> the Berkeley Heights telephone exchange that provided the trunk line to our
> lab off line as they didn't have timeouts and needed to be manually reset.
> But hey, we were the phone company too so what could they do about it?
> 
> Oh, I think that the PDP-11/10s were used because we tried to use LSI-11s
> but those turned out to be useless because of the way that DEC did the DRAM
> refresh; it wasn't interleaved, they just stopped everything every so many
> ms and refreshed everything.  Non-starter for real-time systems.
> 
> And another thought, this machine may have been why Heinz wrote MERT.
> 
> I was gone before this system was completed so I have no idea how it fared
> and how many of the ideas were incorporated into production systems.  Oh,
> yeah, I think that it was called the SS1 for Slave Switch 1.
> 
> Jon