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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 20th Apr 2017, 7:42 pm   #1
JohnBHanson
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Default ASR33 Teletype nostalga question

When I was at university I used a Teletype connected to a mainframe via GPO lines. These worked on 80 volt signalling and had a GPO420 4 pole jack socket. The Teletype control unit - which is to the right of the platen was a special I think and had some illuminated push buttons on it.

It also had automatic paper tape reader control and remote power on from the computer and automatic power off after a time at idle. The paper tape control leaver was non latching allowing the computer to control the reading of the paper tape (just in case 10cps was too quick for the computer - and that did happen!).

I have never found any information on these units. Were they a special GPO or ICL/IBM variant of the standard ASR33.

Anybody remember these?
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Old 21st Apr 2017, 4:08 am   #2
TonyDuell
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Default Re: ASR33 Teletype nostalga question

There are dozens of official Teletype versions of the Model 33. A look at the parts list will show versions with a separate keyboard, sprocket feed (with top-of-form setting), various control code optios, various type cylinders, etc. There was even a numeric-only keyboard. Remote reader control (XON/XOFF characters), that was a standard option too.

As for the 'call control unit' (the electronics chassis to the right of the printer mechanism there were many versions of that too, including versions with punch-card operated pulse or tone autodialers for US lines.

The normal Teletype call control unit used with computers gave you a 20mA or 60mA current loop interface. The connections were a barrier strip inside (with 115V mains on 2 of the terminals just to catch the unwary!). The only user control was a knob on the front of the teleprinter, local/off/remote.

To complicated matters further, in the UK the Data Dynamics company made a series of teleprinters using Model 33 mechanicals (keyboard, printer, punch, reader) and their own electronics in a metal (rather than plastic-top) case. Their electronics often added extra features like an RS232 interface, single-stepping the reader, etc.

And there were many 'unofficial' modifications. Just about every computer manufactuer who used the Model 33 locally connected to their machine added a relay to allow the computer to directly control the tape reader. DEC, Intel and HP all did, the modificatons are pretty similar.

To get back to your question, Teletype never used the Plug 420, but it was commonly used in the UK. I've seen it used at universities for teletype current loop connections. I don't think Teletype used the 80V line directly, but there could well have been an interface in the stand or something. The illuminated buttons sound more Data Dynamics than Teletype to me. The reader control and motor time-out could have been Teletype options or something custom.
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Old 21st Apr 2017, 2:02 pm   #3
G6Tanuki
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Default Re: ASR33 Teletype nostalga question

As stated, there were loads of variants of the "33" - whether RO ASR or KSR. Teletype Corporation/Westrex had a modular approach to the build-sheet and an options-list as long as your arm.

I have memories of running night-shift ops for a small engineering company in 1976/77 - they had an ICL 1901 [well, actually an ICT 1901 it was that old...] running under EXEC and it used an ASR33 as the console. Since many of the command-sequences were repetitive night-after-night I did the obvious and punched up a set of paper-tapes - something the previous ops had neber thought of doing - so could sit back and save finger-time.

After a while you got to be able to foretell the success or failure of a particular job [remember this was all overnight batch-runs - doing stuff like materials-resource planning and stores requsitions] from the chatter of the ASR so could reach for the appropriate 'next stage' tape without needing to actually look at the console-messages in much detail.


There was another KSR33 kept in a locked office at the same company - this was a dialup [hard-wired - can't remember if it used a modem-over-ordinary-phone-lines or was somehow piggy-backed onto the Telex network? It definitely didn't use an acoustic coupler] to "BARIC" - a joint-venture computer-bureau run by Barclays and ICL - that was used to process the likes of payroll and printing out cheques to pay suppliers. These days I guess you'd call this "cloud computing" but I still remember the "three pings" signoff the BARIC '33 used to give on its bell once a day's job load had been submitted and the session disconnected.
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Old 21st Apr 2017, 5:34 pm   #4
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Default Re: ASR33 Teletype nostalga question

Back in the 70's at Plessey Avionics and Communication the ASR33 or it might have been a KSR33 was the device of choice.

The punch tape readers were used to program the Computer Appreciation Naked Mini's which were used to create digital traffic.

It was also used to code the proms again using the punch take the EPROM programmer used an Intel 8080 development system with a bit of additional hardware ISTR the PROMS were 1702's and 5306's

Coding was done on the same machines creating punch tapes as you went there was a little kit to null mistakes on the punch tape it was pretty primitive!

You could also use the Development systems or the Naked Mini's to create the code and then dump it to the punch tapes.

A lot of the time there would be two or three of these machine banging away or reading or writing punch tapes.

I left that project in 1978

I expect everyone remembers the punch tapes that did the rounds of the Naked Ladies

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Old 21st Apr 2017, 5:49 pm   #5
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Default Re: ASR33 Teletype nostalga question

Quote:
Originally Posted by Cobaltblue View Post
I expect everyone remembers the punch tapes that did the rounds of the Naked Ladies
Though not familiar with the specific examples, a realm of paper-tape/card-deck printer-based erotica are truly well-embedded in the annals-of-computing. "Test69" [designed to well-exercise the multiple-overprint and default-programmed paper-fold-avoiding abilities of a 130/132-column lineprinter] comes to mind. I always carried my 'test images' on a small 400-foot 9-track 800BPI open-reel tape, which could be read by virtyally anything.

Somewhere out there surely there's an archive of these?
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Old 22nd Apr 2017, 1:44 am   #6
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Default Re: ASR33 Teletype nostalga question

If you had too many corrections in a tape, you could always just re-punch it and the corrections would just be skipped. You sometimes had to re-punch well-used tapes anyway.

We had mostly gone over to VT-220s and clones by the time I got to Uni, but there was still some ancient kit knocking about -- and my first employer still had CNC machinery that used to use 7/8-bit punched paper tapes for program storage, up to at least 2002 and probably beyond.

I wouldn't be at all surprised if someone was making a device that used a microcontroller and an SD card to emulate a tape punch and reader, just to keep these old machines going.
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Old 22nd Apr 2017, 7:11 am   #7
JohnBHanson
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Default Re: ASR33 Teletype nostalga question

I remember someone making a circuit that would pretend to be a paper tape reader based on a uv-eprom and some TTL counters etc at Plessey in Poole. It would start at address 0 of the uv-eprom and just send consecutive data to the computer. This meant that loading the software took a few seconds and not 20 minutes.

I guess in today's technology a micro-controller would be used to do the same thing.

I have implemented a disk emulator based on a serial port before as well as a fileserver based on a serial port. This allowed a PC to be used as a disk server with older technology.

However I still love the old technology - BTW does anyone still program with paper tape and a teletype?
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Old 22nd Apr 2017, 10:43 am   #8
TonyDuell
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Default Re: ASR33 Teletype nostalga question

Quote:
Originally Posted by JohnBHanson View Post
However I still love the old technology - btw does anyone still program with paper tape and a teletype?
Yes, I do, sometimes. Several of the computers here have paper tape readers (in at least one case it's the only storage device).

The ASR33 is not a good tape reader though. It's only 10 character/second, and being mechanical it's hard on the tapes. I have a couple of Teletypes but never use them for serious tape reading. I use a Trend Data Systems optical reader if I can. Much kinder on the tapes and they do 500 or 700 characters/second depending on the model. And very easy to keep going. Just about the only part to fail is the bulb, and in most of them it's a normal 12V 21W '382' car bulb..
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Old 22nd Apr 2017, 10:58 am   #9
mike_newcomb
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Default Re: ASR33 Teletype nostalga question

John - do you recall if the system you accessed/used was called Minimop or Maximop?

Hi G6Tanuki, I have same fond memories.
My first mainframe was an ICL-1909 and 'driven' manually using a teletype. This was a scientific machine but used in a commercial bureau. Having many Tape Decks we were able to multi-stream programs
Originally it did not have disks, only mag tapes, punch cards and paper tape.

I think the Baric centre you mention was in Harlesden opposite Scrubs Lane. When the centre moved or closed, the building remained on sale forever. There were no takers as it was a purpose built computer centre. Eventually it was demolished and replaced with flats.

Regards - Mike
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Old 22nd Apr 2017, 6:02 pm   #10
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Default Re: ASR33 Teletype nostalga question

My one and only exerience with a '33 was at (the then) Lanchester Polytechnic, where one was made available to our school. I was astounded that it shook so much! Amazing to think it is all electromechanical.

My current interest is their frequent use with the earliest microprocessor systems ( visual displays came later). I suspect it is no coincidence that BASIC lists in the same format as a program is entered. This was exploited to save programs by turning on the punch before completing a 'LIST' command.

I missed all that, of course. And I missed the analogue era
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Old 22nd Apr 2017, 6:25 pm   #11
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Default Re: ASR33 Teletype nostalga question

Quote:
Originally Posted by mike_newcomb View Post
I think the Baric centre you mention was in Harlesden opposite Scrubs Lane. When the centre moved or closed, the building remained on sale forever. There were no takers as it was a purpose built computer centre. Eventually it was demolished and replaced with flats.
Though there may have been a BARIC centre in Harelsden [to serve clients in the Metropolis and surroundings] from memory the one we used was somewhere in Staffordshire - which would make sense since we were in the West Midlands and ICL had at the time a major development/manufacturing operation in Kidsgrove.

In the days of having to get data/telex circuits from the Post Office there would have been sense in minimising any distance-related components of line/connection-charges and so connecting to the nearest centre. Kidsgrove would have been a sensible centre for Manchester/Liverpool clients too.

When I went to university in 1978 I took with me a whole bunch of BARIC forms which were only printed on one side, so I used the unprinted reverse-side to take down my lecture-notes.

Must do some more research on BARIC. They were at one time a big player in the computer-bureau business.
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Old 22nd Apr 2017, 7:25 pm   #12
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Default Re: ASR33 Teletype nostalga question

Programming in CECIL over a teletype link in 1974, ah memories!
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Old 22nd Apr 2017, 8:41 pm   #13
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Default Re: ASR33 Teletype nostalga question

The system used via the teletype ran an operating system called MultiJob. Apparently it was the only operating system that supported the networking of university mainframes throught the south western area. Bath and Bristol, UMIST and a couple of others were involved.

I have used MiniMop which I used at plessey on a george 3 system. The terminals that
were used were 300 baud decwriter2 machines. This was at Plessey Poole - I remember
moving into a portacabin.
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