Discussion:
Talking of DecWriters ...
(too old to reply)
Gareth Evans
2020-04-10 11:19:55 UTC
Permalink
Where I was working in 1973 / 74, the Scientific Services
Department of the CEGB co-sited at Portishead Power Station,
where, incidentally, I had cut my teeth on a blinkenlights
PDP11/20 as an undergraduate intern in 1971, we took delivery
of a DecWriter on a very high quality pallet, which had a single flat
square of thick plywood instead of multiple slats.

What a boon to a young married couple was that pallet, for we
still have the bookcase that we constructed from that sheet
of plywood, an absolute necessity in our then
impoverished state, being then unable to afford any new
furniture! :-)
m***@gmail.com
2020-04-10 13:13:34 UTC
Permalink
Where I was working in 1973 [...]
Ah yes, 1973! Recently separated from the U.S. Army, where I had been a Nuclear Weapons Electronics Specialist, I was working in downtown Seattle as a security guard at the headquarters of the National Bank of Commerce. My former Greek professor called me up to suggest that I apply for a job-opening as a Latin teacher at The Overlake School in Redmond WA USA, so I went out there and interviewed with the headmaster, Robert Dean Palmer, for the job teaching both Latin and German. My shrink father told me that he had a psychiatric patient named Bill Boeing, Jr., who was on the board of trustees of the private high school, and my father could ask Mr. Boeing to put in a good word for me, if I wanted. Eager for any help I could get, I agreed. So in fall of 1973 I started teaching.

Every spring the school had something called "Project Week," and for several years I had kids come to my classroom to spend a week building transistor radio receivers from kits sold by Radio Shack. Meanwhile at a 7-Eleven store in Seattle I bought a magazine describing the Mark-8 microcomputer, which you could either buy as a kit and assemble, or you could send five dollars to Berkeley CA USA and receive the printed plans for the Mark-8, purportedly the world's first microcomputer, although some claim that title for the Altair. I sent $5.00 away for the Mark-8 schematics, and years later a former student of mine who had the kit but not the schematics was glad to receive them from me.

In 1973 I was already working on my Mentifex AI project, but still in the mind-design and planning phase. Now more recently in the current year of the plague the AI project is maybe catching on, maybe not. When my shrink father's patient passed away a few years ago -- releasing me from obligations of psychiatric privacy -- I was surprised to learn that his own son had pre-deceased him. Meanwhile, all the Boeing airplane factories have closed down, due to the coronavirus, and so the deadly Boeing jets are no longer killing plane-loads of passengers and polluting the skies. For many decades, Boeing airplanes were of extremely high quality and safety, until the bean-counters over-ruled the engineers and pursued only monetary profits with a safety-be-damned attitude. 1973 -- if only we could clap our hands and be back in that year when https://en.wikipedia.org/wiki/Ken_Olsen was running Digital Equipment Corporation.

http://ai.neocities.org/Abracadabra.html -- was eventually my artificial intelligence thinking in ancient Latin.
Mike Spencer
2020-04-10 19:53:28 UTC
Permalink
Post by Gareth Evans
Where I was working in 1973 / 74, the Scientific Services
Department of the CEGB co-sited at Portishead Power Station,
where, incidentally, I had cut my teeth on a blinkenlights
PDP11/20 as an undergraduate intern in 1971, we took delivery
of a DecWriter on a very high quality pallet, which had a single flat
square of thick plywood instead of multiple slats.
What a boon to a young married couple was that pallet, for we
still have the bookcase that we constructed from that sheet
of plywood, an absolute necessity in our then
impoverished state, being then unable to afford any new
furniture! :-)
In 1990, a university professor for whom I'd repaired some antique
andirons gave me -- persuaded me to haul away -- a DecWriter II,
complete with acoustic coupler that worked fine with our Nortel 500
dial phone. Free 132 col. fan-fold paper from same university's VAX,
already printed on one side. Used it to connect to a local BBS,
conected it to my Osborne I as a printer. Printed out an entire
strategy game in BASIC that could be marked up in particolored felt
tip in order to figure out how to translate it to C. Lots of fun.

Eventually, the motor -- the one with the optomechanical widget on one
end -- started slamming the printer head around indiscriminately. The
DEC office in Halifax pronounced themselves happy to send a service
tech 75 miles to my rural farm house and fix me right up but, of
course, at stndard corporate/academic hourly/travel rates. RIP
DecWriter.

But like the OP, I have a long-term residual benefit. The very sturdy
steel support frame, topped with plywood (for $$, not part of the
DecWriter donation) now supports 3 computers, 2 CRT monitors,
digital-cam-equipped microscope and CD collection very stably.
--
Mike Spencer Nova Scotia, Canada
Terry Kennedy
2020-04-11 03:14:47 UTC
Permalink
Post by Mike Spencer
Eventually, the motor -- the one with the optomechanical widget on one
end -- started slamming the printer head around indiscriminately. The
DEC office in Halifax pronounced themselves happy to send a service
tech 75 miles to my rural farm house and fix me right up but, of
course, at stndard corporate/academic hourly/travel rates. RIP
DecWriter.
Those optical encoders are a bit twitchy, particularly if you operate the printer out of spec.

1) There is a hack to force it to use "catch-up speed" (60 CPS) all of the time, instead of only at the beginning of the line (to recover from the mechanical delay of the carriage return/linefeed). But then your host OS needs to do NUL padding at every EOL.

2) Datasouth (later of the DS180 and DS220 printers) got their start with a replacement board for the LA36/DECwriter II that made it perform at the speed of a LA120/DECwriter III, along with other goodies. If you called them (actually, pretty much Jim Busby, the founder) with print problems they would send you a replacement motor/encoder that they had checked out, along with a replacement board. You sent back whichever was the problem part and the other part as well.

The LA36 does not have any sort of dedicated "home" (column 1) sensor. On power-up, it slowly moves the carriage to the left until it hits the bump stop and the encoder stops generating pulses. It then backs off a few encoder positions and uses that as the column 1 reference. If the encoder malfunctions, you'll find the dots creeping one way or another by one dot width, until the printhead starts slamming into the home stop. You need a power cycle to get things back in order. Also, if you can grasp the printhead firmly enough at power-on, you can fool the printer into thinking that's the home position.

DEC came out with the DECwriter IV (LA34) which was a horrible piece of junk compared to either the II or the III. Tabletop and flimsy.
Scott Lurndal
2020-04-13 14:45:19 UTC
Permalink
Post by Mike Spencer
Eventually, the motor -- the one with the optomechanical widget on one
end -- started slamming the printer head around indiscriminately. The
DEC office in Halifax pronounced themselves happy to send a service
tech 75 miles to my rural farm house and fix me right up but, of
course, at stndard corporate/academic hourly/travel rates. RIP
DecWriter.
Those optical encoders are a bit twitchy, particularly if you operate the p=
rinter out of spec.
1) There is a hack to force it to use "catch-up speed" (60 CPS) all of the =
time, instead of only at the beginning of the line (to recover from the mec=
hanical delay of the carriage return/linefeed). But then your host OS needs=
to do NUL padding at every EOL.
2) Datasouth (later of the DS180 and DS220 printers) got their start with a=
replacement board for the LA36/DECwriter II that made it perform at the sp=
eed of a LA120/DECwriter III, along with other goodies. If you called them =
(actually, pretty much Jim Busby, the founder) with print problems they wou=
ld send you a replacement motor/encoder that they had checked out, along wi=
th a replacement board. You sent back whichever was the problem part and th=
e other part as well.
The LA36 does not have any sort of dedicated "home" (column 1) sensor. On p=
ower-up, it slowly moves the carriage to the left until it hits the bump st=
op and the encoder stops generating pulses. It then backs off a few encoder=
positions and uses that as the column 1 reference. If the encoder malfunct=
ions, you'll find the dots creeping one way or another by one dot width, un=
til the printhead starts slamming into the home stop. You need a power cycl=
e to get things back in order. Also, if you can grasp the printhead firmly =
enough at power-on, you can fool the printer into thinking that's the home =
position.
DEC came out with the DECwriter IV (LA34) which was a horrible piece of jun=
k compared to either the II or the III. Tabletop and flimsy.
The LA120 was pretty nice, and less maintenance than the ASR33 it replaced...
r***@gmail.com
2020-04-14 01:20:42 UTC
Permalink
Post by Scott Lurndal
The LA120 was pretty nice, and less maintenance than the ASR33 it replaced...
What maintenance does an ASR33 need?
David Wade
2020-04-14 10:10:01 UTC
Permalink
Post by r***@gmail.com
Post by Scott Lurndal
The LA120 was pretty nice, and less maintenance than the ASR33 it replaced...
What maintenance does an ASR33 need?
It should be doused in lubricated fairly often. The instructions for
that run to 16 pages. Not exactly trivial...

https://www.soemtron.org/teletypemanuals.html#Body

Under normal use appears to need doing every 3 months or so.
The rubber type hammer wears. ASR has punch and reader which tend to
need adjustment.

Lets face it, take the covers off and its steam punk with no changes....

Dave
Peter Flass
2020-04-14 13:29:12 UTC
Permalink
Post by David Wade
Post by r***@gmail.com
Post by Scott Lurndal
The LA120 was pretty nice, and less maintenance than the ASR33 it replaced...
What maintenance does an ASR33 need?
It should be doused in lubricated fairly often. The instructions for
that run to 16 pages. Not exactly trivial...
https://www.soemtron.org/teletypemanuals.html#Body
Under normal use appears to need doing every 3 months or so.
The rubber type hammer wears. ASR has punch and reader which tend to
need adjustment.
Lets face it, take the covers off and its steam punk with no changes....
We had a terminal room with three or four - only programmer access, no
students. It seems like one or another was often down.
--
Pete
r***@gmail.com
2020-04-15 01:07:36 UTC
Permalink
Post by David Wade
Post by r***@gmail.com
Post by Scott Lurndal
The LA120 was pretty nice, and less maintenance than the ASR33 it replaced...
What maintenance does an ASR33 need?
It should be doused in lubricated fairly often. The instructions for
that run to 16 pages. Not exactly trivial...
Not beyond the capabilities of someone with an oil can.
Pretty well most mechanical equipment needs oiling.
Post by David Wade
https://www.soemtron.org/teletypemanuals.html#Body
Under normal use appears to need doing every 3 months or so.
The rubber type hammer wears.
About once every 10 years.
Post by David Wade
ASR has punch and reader which tend to need adjustment.
Lets face it, take the covers off and its steam punk with no changes....
I managed to do the maintenance without problems.

Even worked out how to print with a carbon ribbon
when high quality was required for photography.

Loading...