Origin of 'Straight 8' name

David C. Jenner classiccmp at earthlink.net
Fri Dec 21 22:34:17 CST 2018

In 1968-69 my bedroom was right over PDP-8 #6.  It's been 50 years, but 
it may have been referred to as a "straight-8" then?

On 12/21/18 12:51 PM, Jim Carpenter via cctalk wrote:
> On 12/21/18 1:10 PM, Al Kossow via cctalk wrote:
>> On 12/21/18 10:03 AM, Al Kossow via cctalk wrote:
>>> "Straight-8" seems to be a fairly modern name coming from collectors
>>> I never heard it called that before then.
>> Anyone feel like doing a alt.sys.pdp-8 search for it by date?
> The PDP8-LOVERS mailing list predates alt.sys.pdp8 by a couple years. I 
> just checked the archives and the earliest usage of 'straight-8' is from 
> Charles Lasner in an e-mail introducing himself to the still new mailing 
> list on August 10th, 1990. I've pasted his complete message at the 
> bottom. The 'straight -8' is mentioned in the second sentence of his 
> second paragraph.
> A quick check shows that it was common for cjl to use the term 
> 'straight-8'.
>> I don't feel like going down the rathole of trying to find a way to
>> search Usenet by date right now.
> I miss DejaNews. Damn I hate Google.
> Jim
> Received: from ELI.CS.YALE.EDU by BUGS.SYSTEMSY.CS.YALE.EDU; Fri, 10 Aug 
> 90 05:37:28 EDT
> Received: from life.ai.mit.edu ([]) by ELI.CS.YALE.EDU; Fri, 
> 10 Aug 90 05:36:07 EDT
> Received: from watsun.cc.columbia.edu by life.ai.mit.edu (4.1/AI-4.10) 
> id AA00254; Fri, 10 Aug 90 05:12:04 EDT
> Received: by watsun.cc.columbia.edu (5.59/FCB)
>          id AA20618; Fri, 10 Aug 90 05:12:20 EDT
> Date: Fri, 10 Aug 90 5:12:19 EDT
> From: Charles Lasner <lasner at watsun.cc.columbia.edu>
> To: PDP8-LOVERS at ai.mit.edu
> Subject: Belated Mail Reply
> Message-Id: <CMM.0.88.650279539.lasner at watsun.cc.columbia.edu>
> Date: Fri, 10 Aug 90 5:12:19 EDT
> From: Charles Lasner <lasner at watsun.cc.columbia.edu>
> To: PDP8-LOVERS at ai.mit.edu
> Subject: Belated Mail Reply
>  >Received: from AI.AI.MIT.EDU (CHAOS 3130) by MC.LCS.MIT.EDU 18 Feb 89 
> 10:32:35 EST
>  >Date: Sat, 18 Feb 89 10:32:31 EST
>  >From: "Robert E. Seastrom" <RS at AI.AI.MIT.EDU>
>  >To: pdp8-lovers at MC.LCS.MIT.EDU
>  >Message-ID: <540513.890218.RS at AI.AI.MIT.EDU>
>  >
>  >
>  >Well, folks, it's finally here.  The PDP8-LOVERS mailing list is now
>  >reality!  Messages for the list go to PDP8-LOVERS at MC.LCS.MIT.EDU;
>  >requests to be added to or deleted from the list go to
>  >PDP8-LOVERS-REQUEST at MC.LCS.MIT.EDU (case is _not_ critical here).
>  >
>  >Perhaps we ought to all introduce ourselves to each other...
>  >
>  >          This one's for you <7001>
>  >
>  >                      -Rob
> From:   cjl
>      Let me introduce myself.  I am Charles J. Lasner.  I only use the
> J to get my initials, which I usually go by, thus cjl.
>      I am a PDP-8 programmer.  I don't know how many of us there are
> left, but I started in 1968 with a straight -8 table-top machine at
> Brooklyn PolyTechnic Institute.  The school probably has another name
> by now, due to academia's answer to the business world's phenomena of
> acquisitions and mergers.  The machine in question is quite
> legendary.  The work done on it is responsible in LARGE part for why
> all of us are here reading this, since this is the "original" PDP-8
> used by the legendary Richard Lary and company.  If it can be said
> that the PDP-8 created the phrase "mini-computer", then it is THIS
> PDP-8 that made the "mini-computer" into something other than a
> paper-tape machine!
>      This PDP-8 was originally configured by the academics in charge
> as a programmer's disaster: 4K, EAE, a model 33 teletype, AF01A A-D
> converter with 16-channel multiplexor,  AA01A D-A converter with
> (wow!) THREE channels.  A Bud blue rack cabinet housed the A-D and
> D-A with lots of empty space.  All empty slots had those wonderful
> super-thick zinctone panels, and the fronts were all in place; they
> were held in place with those pressed-in heavy shiny metal threaded
> bosses that most of you can't figure out the purpose of on your
> wire-wrap racks.  As far as I know, these were the only style of
> cabinet that the bosses were supplied for.  The plates used heavy
> nickel-plated knurled knobs with a screw-driver slot you could turn
> with a dime.
>      Soon after all of this arrived, and got nowhere due to the
> enormous waste of time paper-tape can be (especially at 110 baud and
> unreliable at that!), a DEC salesman suggested a high-speed
> reader/punch be added.  Fortunately for all of us, THIS NEVER
> HAPPENED, for if it had, no further work of external significence
> would have been done.  (The EE department would have been very happy
> to just develop their diddly A-D and D-A experiment programs.)
>      Due to the efforts of Richard Lary, Jack Burness, Hank Maurer,
> Lenny Elekman, and Joseph R. Fischetti (to name a few legends I
> knew), the EE department was convinced to spend MORE money on some
> new-fangled beast the salesman had vaguely heard of; he was fairly
> certain it was called a MicroTape.  This was, of course, an early
> name for DECtape.  So the EE department shelled out another $8k and
> got itself another Bud blue rack cabinet complete with sides, another
> power controller, 11 buss cables, and a TC01 and one (yes one!) TU55
> DECtape drive.  The academics thought that the drive was custom made
> for the PDP-8, because the numeral "8" always appeared on the drive
> select.  (No need to change drives when you have only one of them!) I
> later found out why the "8" was there (not "0"):
>      This is a throwback to the earlier Microtape drives used mostly
> on the PDP-6 which are really DECtape drives, but with an entirly
> different interface to the PDP-8, which really belongs to the PDP-5
> era.  I believe that the PDP-5 doesn't support 3-cycle data-break,
> because this is a single-cycle interface.  This limits programming
> possibilities. (Another subject entirely!)
>      I believe the only programming for this earlier hardware was an
> original version of the DECtape Library System which I had contact
> with on the TC01/TU55 (an incompatible later version, but obviously
> less obscure).  The interesting point is that while the TC01 has a
> three-bit drive select register, where all cases are viable, this
> earlier hardware had a FOUR-bit register, so drives had to be
> selected as 1-8.  Clearing the register deselects all drives, whereas
> when talking to the "Solid-State DECtape" drive, as the TU55 was
> originally known, you are selecting drive zero.  Apparently there
> were hardware adaptations to theoretically connect the TU55 as a
> microtape drive (using RELAY LOGIC level converters instead of the
> jumper cards usually in the drives), so they thought in terms of the
> original microtape nomenclature of 1-8.  Years later (I think first
> done for the benefit of the PDP-12 LINCtape) they had an ECO to glue
> a 0 over the 8.
>      Soon after the TC01/TU56 cabinet arrived, the 33 teletype started
> failing (which is normal!) from "normal" use (reading paper-tapes!).
> They had their first "run-in" with DEC Field Service, whose members
> sort of knew what to do with the -8, but they KILLED teletypes!
> Eventually, they purchased a PT08, the only hardware on this machine
> to use ICs (RTL chips only, TTL came later!).  With it came an
> additional teletype, a model 35 (without paper-tape).  The 35 became
> the 03/04-connected one, and the 33 was "banished" to the PT08. (And
> over the years it "walked" out of the PDP-8 room to be "borrowed" by
> various groups, only to be "retrieved" periodically.)
>      Fortunately, a private teletype maintenance company contacted the
> school and eventually won a teletype-only maintenance contract, over
> DEC's objections.  Since these teletypes were so over-used, it became
> necessary to rotate them between the PT08 and the console to keep
> them working.  We even created software to SLOW DOWN the teletype,
> since it was noticed that an out-of-adjustment 35 will work FINE if
> run at 89% of maximum speed (that's 89% of 110 baud!) when it starts
> jumbling characters at 100% speed.
>      This machine was setup on a large desk, with the teletypes
> nearby, and a Bud cabinet at either end.  We didn't have the nice
> Formica table option.  So much software was toggled into this machine
> that I personally replaced the slide switches which wore out!  I also
> repaired the CPU several years later, after DEC Field Service swore
> they couldn't get it to work after 9 months of trying.
>      The problem was that there are isolation diodes in the wires that
> run from various registers to the light panel, which has lamp drivers
> and soldered in lamps on it.  Periodically we would replace the
> occasional blown transistor driver and numerous blown bulbs.
> (Touching the panel was a calculated risk since you killed even more
> lamps by doing it!)
>      The diodes are located on the card edge where all of the wires
> are soldered close together, and plugged into the backplane; there
> are several such cards.  The wires break off easily, and hasty
> repairers would sloppily solder them back to the board lugs.
> Eventually some diodes shorted, so the capacitance of the wires now
> loaded the affected driver.  Also there now was the possibility of
> cross-talk between the wires collector-triggering the gates!  This is
> why the machine was so prone to random failure.  (It worked in
> single-step mode.)
>      Replacing the diodes didn't completely work, because there was
> yet another problem: the diodes were photo-sensitive!  DEC attempted
> to light-shield the diodes by painting them.  This paint got scraped
> off of them due to the soldering, etc., so the machine was sensitive
> to its own lamps being lit!  It worked better in room darkness, so we
> got the idea about inadvertent photo-diodes!  Painting the diodes
> solved the last remaining problem.  I almost single-handedly got the
> machine back up (there were other random problems as well, but they
> were easier to solve, like the tendancy for a PT08 to burn up a land
> UNDER a chip where you couldn't see it!), and got the thanks of the
> faculty members of the EE department, who would have scrapped the
> machine if it was unrepairable!
>      Although this wasn't my first computer, it was my first DEC
> computer.  I have stayed with the PDP-8's to this day.  I was then
> and now a programmer, but we all participated in keeping the machine
> up.  I can trace my extensive DEC hardware background to this
> beginning (as well as DEC software!).
> cjl (Charles Lasner)
>      (lasner at watsun.cc.columbia.edu or lasner at cunixf.cc.columbia.edu)

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