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From: Earl Baugh <>
To: Jon Steinhart <>
Subject: Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]
Date: Wed, 15 Jan 2020 03:05:16 -0500
Message-ID: <> (raw)
In-Reply-To: <>

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 :-) 


Sent from my iPhone

> On Jan 15, 2020, at 2:12 AM, Jon Steinhart <> wrote:
> Earl Baugh writes:
>> Why not build a variation of this with an Arduino?
>> 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

  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-15  3:32 [TUHS] Spacewar at Bell Labs Brian Walden
2020-01-15  4:01 ` Jon Steinhart
2020-01-15  4:50   ` Bakul Shah
2020-01-15  6:17 ` Lars Brinkhoff
2020-01-15  6:34   ` Earl Baugh
2020-01-15  7:10     ` [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Jon Steinhart
2020-01-15  8:05       ` Earl Baugh [this message]
2020-01-15 14:50       ` Clem Cole
2020-01-15 23:40         ` Al Kossow
2020-01-15 12:29     ` [TUHS] Spacewar at Bell Labs John Foust
2020-01-16  0:17       ` [TUHS] tape reading (was Re: Spacewar at Bell Labs) Al Kossow
2020-01-15 16:46 [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Noel Chiappa
2020-01-15 18:35 ` Clem Cole
2020-01-29 20:25 ` Dave Horsfall
     [not found]   ` <>
     [not found]     ` <>
2020-02-04 20:26       ` Dave Horsfall

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