Any other older folks learn to program with this? - Page 1
Forum section: electronics / general

author: Housedad
author_rank: Frequent Contributor
timestamp: May 26, 2017, 06:28:53 am
content: PDP 8 and a Teletype. I Played with one every day after classes in High school 1973 -1976. Anyone that walked into the math lab at school was automatically labeled a nerd.Video of a teletype working:http://www.pdp8online.com/asr33/videos.shtml

author: coppice
author_rank: Super Contributor
timestamp: May 26, 2017, 06:33:57 am
content: Were you limited to using paper tape on the ASR33 for all I/O? That was a common PITA with those machines and the Data General Nova.

author: CJay
author_rank: Super Contributor
timestamp: May 26, 2017, 06:46:08 am
content: Before my time a little but in the 'computer science lab'* at my secondary school we had a similar looking teletype which was linked to the 'mainframe' at the local university, you had to book time on it and be in the lab extra early to get your allocated timeslot as the mainframe was 'for students' during normal school hours. Of course it wasn't possible to ever get any time as none of the teachers would turn up early or make themselves available before school.We weren't allowed to touch the teletype and I never saw it switched on.*Computer science lab was a grandiose name for a room with a defunct teletype, a Commodore Pet and a year or two later a couple of BBC Micros, the school had a grand total of 10 BBCs by the time I left and those on the computer studies O level course were given strong preference for access to them, fortunately for those of us who weren't deemed good enough to have been admitted to the course there was 'computer club' after school where we could use the machines for our own purposes because the chosen few very rarely bothered to stay behind.Education in the UK was and probably is still rather pathetic when it comes to technical subjects but we can always import skilled programmers and techs right? (heavy sarcasm)

author: Housedad
author_rank: Frequent Contributor
timestamp: May 26, 2017, 06:48:49 am
content: yes, I/O was all paper. Either via the keyboard or paper tape. We all carried a program in our pockets by folding the tape into a flat accordion 6 to 8 inches long. just be careful you don't spill your lunch on it!!

author: coppice
author_rank: Super Contributor
timestamp: May 26, 2017, 07:36:56 am
content: Quote from: CJay on September 28, 1974, 05:28:36 amWhen I went through the UK school system in the 60s and early 70s it was possible to get an excellent technical education in many schools. Of course the UK had not given up its position as an advanced nation at that time, and was still a technology leader in many fields.

author: nali
author_rank: Frequent Contributor
timestamp: May 26, 2017, 08:09:25 am
content: Quote from: Housedad on May 26, 2017, 06:48:49 amOur school obtained a teletype just before I left in 1979, although it was not much more than a novelty item so didn't get used much beyond "Hello what is your name" (I think it was added to the curriculum the following year)After that I served an apprenticeship at Rank Industrial; one of the products they did was a PLC control which used punch tape for storage and was still sold or maintained into the mid/late 80s. I vaguely remember a folder containing test routines held on dog-eared paper strips with more than the occasional Sellotape reinforcement!

author: tggzzz
author_rank: Super Contributor
timestamp: May 26, 2017, 08:10:16 am
content: A PDP8 was rather too modern; I used an Elliott 803.Ditto ASR33s; I used 5 channel paper tape with teleprinters. Exercise for youngsters: encoding letters, digits and punctuation is easy on 8 channel paper tape, but how do you do it with 5 channels?I last saw a working 803 and played (briefly) with an ASR33 last Sunday, at TNMoC - probably the best museum in the world, since the staff know what they are talking about.

author: CJay
author_rank: Super Contributor
timestamp: May 26, 2017, 08:20:23 am
content: Quote from: coppice on May 26, 2017, 07:36:56 amWe seem to have dropped the ball somewhat and have been scrabbling to pick it up again for the last few years (decade?), ever hopeful that we can begin to teach tech subjects at more than a superficial level and inspire generations to become the engineers we are apparently so desperate for.

author: Towger
author_rank: Super Contributor
timestamp: May 26, 2017, 08:37:59 am
content: Quote from: CJay on May 26, 2017, 06:46:08 amOur 'Computer science lab' was a large purpose built modern room, with sockets around the walls and selection which could be divided off with a large steel shutter for security. It was used as a normal class room. The computers were 3 Apple II(e?) (2 worked) in a small 1950's closet type room at the ends of a corridor, beside the boys toilets. We (the good children) were allowed to used them at allocated times before/after school unattended, just had to request the key from the staff room. Not always an easy task, depending on who open the door of the smoke filled room.Those were days, the computer teachers barely knew what hard disk was. Before I left we got a few IBM PS/1s. IBM could not sell them, so they were given away to schools, when you collected enough tokens from various supermarkets. But these were much too high tech for the teachers, so we ended up teaching them...

author: Housedad
author_rank: Frequent Contributor
timestamp: May 26, 2017, 09:22:39 am
content: It's funny. Back then, there were just four of us students that bothered to learn about the weird contraption in the Math Lab. This is out of a class that graduated with 1200 students and a school of 4000! At least the moderator, the head of Math department, was well versed in it and could teach us.Along with the two teletypes in the lab, there was another that was reserved to be hooked to the phone line with an acoustical 110 baud modem. That one communicated to the University of Pennsylvania systems for us to peruse after 4:00 pm. Needless to say, we stayed late a lot.The school is in Broomall, Pa, just a few miles from Philladelphia and the U of P.

author: brucehoult
author_rank: Super Contributor
timestamp: May 26, 2017, 01:36:01 pm
content: Never came across a PDP8 in the sleepy little town of Whangarei, New Zealand.In 1977, 2nd year of high school, once a friend got a driving license we sometimes went in free periods to another nearby school where there was an HP-97 calculator with built in printer and mag card reader.By 1979 I had a TI-57 (8 memories and 50 program steps) and a richer friend had a TI-58C which had the huge advantage of not losing memory contents when you turned it off.In the last year of high school, 1980, we did some FORTRAN programming in class, using punched cards with every 2nd column pre-scored so you could punch them by hand using a paper clip. In the evenings the teacher would take our card decks to a local bureau to run them. From time to time those interested could accompany. There was a Burroughs B1700 with 48k words of memory, a teletype console, a (chain) line printer, a card reader, and two 5 MB removable disk pack drives. We had our own disk pack with OS and compiler. We'd load our disk pack, put a boot cassette into the console, put a boot card deck into the card reader, rewind it, and load a short 1st stage bootstrap program into memory&registers using front panel switches.The 1st stage bootstrap (only half a dozen instructions I think) could read the card reader. The code from the card deck could read the casette. The code from the cassette could read the disk. Whoa.At the end of 1980, during exam time, the school got their first Apple ][. I was allowed to take it home for a few weeks during the holidays to learn about it and then brief the math teacher.In 1981 I went to university, where the 1st year computer science students had the run of a PDP11/34 with 256 KB RAM with 22 VT100 terminals, two LA120 printers and, again, two 5 MB disk drives. We wrote programs in Pascal. As I recall we had something like 50 KB of permanent disk quota each, though we could use more temporarily while logged in.In 1982 as 2nd year students we had access to the main PDP11/70 with several megabytes of core memory, and soon after to a shiny new VAX11/780 (which wasn't actually any faster, but could run bigger programs).Everything I learned on as a student was slower than an Arduino Uno, though with more RAM.Everything I used professionally in the first 15 years of my career after university, whether desktop, laptop, or mainframe/server, was slower than and had less memory than a Raspberry Pi 2/3.Plus, we had unimaginably worse access to industry news (moths late, in magazines), research, new software...

author: coppice
author_rank: Super Contributor
timestamp: May 26, 2017, 02:50:25 pm
content: Quote from: brucehoult on May 26, 2017, 01:36:01 pmOoooh, digital cassette tapes. You didn't see too many of those. I compiled quite a few Fortran programs from cassette to cassette on a dual digital cassette drive.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 26, 2017, 07:08:45 pm
content: In the late 1960s I was lucky that my local junior college (Orange Coast in Costa Mesa, California) had a rather advanced computer facility. I learned to program on an IBM 1620 and an IBM 1403.The 1620 was a BCD (6-bit) machine and we had a whopping 40K of core memory and a pair of removable-pack hard drives (10mB each)Ironically, a few years later, in my first job out of school, I ended up actually maintaining a 1620. I even added a Centronics parallel printer port to it so we could connect a drum printer.The 1401 was also a BCD (6-bit) machine, more geared for business computing than the "scientific" market for the 1620But by the end of my 2.5 years at OCC, they had installed an IBM System 360/44 and we had a room full of (3rd party) Selectric terminals for programming in APL.We computer lab assistants had a "parlor game" of taking an example code in FORTRAN (or whatever) and re-writing it in APL in typically 1/10th the number of lines of code. Of course, APL had the reputation for being "write-only" as it was nearly indecipherable by humans, even the human who wrote it!

author: grumpydoc
author_rank: Super Contributor
timestamp: May 26, 2017, 07:17:41 pm
content: Quote from: tggzzz on May 26, 2017, 08:10:16 amBaudot, nautrallyNot sure I count as "younger" although I cut my teeth mainly on early Z80 systems - Nascom, Exidy Sorcerer etc so not quite as far back as the PDP8's

author: james_s
author_rank: Super Contributor
timestamp: May 26, 2017, 07:27:54 pm
content: I'm sure those were mostly all gone by the time I was born. I learned to program on Apple II computers in school and later did some more with the PC/XT we had at home.

author: tggzzz
author_rank: Super Contributor
timestamp: May 26, 2017, 09:10:03 pm
content: Quote from: grumpydoc on May 26, 2017, 07:17:41 pmThe first machine code programme I wrote converted one 5 channel code to another. It worked first time (unlike somebody else's program) probably because I triumphantly and unwittingly reinvented FSMs.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: May 26, 2017, 09:11:15 pm
content: Quote from: Housedad on May 26, 2017, 06:28:53 amLuxury! But then, in my day we had it rough...When I was in grade 11 and 12, my school in 1966, Ottawa Tech High was the only school in the city to have a "computer". This one was a PDP-8 and a teletype KSR-33 just like in the video except that the PDP-8 was donated to the school, had been completely disassembled and re-built into a rack frame with all of the switches replaced by small generic toggles and the lights by small incandescent ones. It had no languages so was programmable only in octal/binary through the toggle switches.I was one of a small handful of kids who understood how to use it. We wrote such mind-blowing programs as a tone generator by connecting an amplifier to the carry bit of the accumulator, the "link", or a program to calculate Sin() or Cos() using a power series. The biggest program I did was one to play 3x3 tic tac toe through the keyboard.It had the usual 4K words of core memory. It also had a pen plotter mounted to the wall which could be used to plot points only (no lines) and was excruciatingly slow.Dumbest computer that I have ever seen or used but it was magic at the time!

author: Housedad
author_rank: Frequent Contributor
timestamp: May 26, 2017, 11:07:25 pm
content: Feet? You had FEET?!!!

author: Cerebus
author_rank: Super Contributor
timestamp: May 27, 2017, 12:02:21 am
content: Quote from: brucehoult on May 26, 2017, 01:36:01 pmNot quite, the cassette tape held the processor microcode. Until you had loaded that the machine was basically a chuck of logic that didn't know how to execute anything. You rewound the tape, turned the STEP/RUN/TAPE switch to TAPE and hit the CLEAR then the START button. It actually read microinstructions from the tape and executed them as it read them. Once it got to a certain point it had written enough to the microprogram memory to start executing instructions from there instead. Once the microprogram was fully loaded it halted. You then set the STEP/RUN/TAPE switch to RUN and hit the START button again. Different microcode bootstraps where supplied to boot the system from different media, disk, 1/2" tape, etc.I don't know quite what the card reader was doing in your boot sequence as it was possible to boot MCP straight from disk once you'd loaded the microcode from the cassette reader.

author: retrolefty
author_rank: Super Contributor
timestamp: May 27, 2017, 12:56:41 am
content: Quote from: tggzzz on May 26, 2017, 09:10:03 pmI think the reason for the question to beginners is how one can use a 5 bit baudot coding (32 binary combinations) to represent letters, numbers, punctuations, etc ? The trick is that baudot uses two characters dedicated to switching between two different 32 characters sets, called letters and figures and using those two characters to switch between them. A little kludgy but one used what was available.

author: KJDS
author_rank: Super Contributor
timestamp: May 27, 2017, 05:41:03 am
content: I was using a teletype like that pictured in 1979, connected via modem to a PDP11 at the local technical college

author: tggzzz
author_rank: Super Contributor
timestamp: May 27, 2017, 08:12:18 am
content: Quote from: retrolefty on May 27, 2017, 12:56:41 amAll5 channel codes (of which Baudot is one) relied on lettershift/figureshift.

author: Seekonk
author_rank: Super Contributor
timestamp: May 27, 2017, 08:59:47 am
content: I remember entering the bootloader on front panel switches manually.

author: Brumby
author_rank: Unknown
timestamp: May 27, 2017, 10:06:44 am
content: When I was in high school, there was a Science Weekend organised at the UNSW. There were sessions organised for a variety of disciplines - and one of those was for computing. I signed up for that one!I was sent a little booklet beforehand describing the programming language called FOCAL - which was DECs equivalent of BASIC. It had two sample programs - and I scoured it from cover to cover and back again ... several times. Come the day ... I was ready!The computer was a PDP 8, using teletypes as I/O - but in those days, this was high tech stuff ... especially for a high school kid!A couple of years later as a student at the UNSW, I came across a PDP 8 in the Electrical Engineering building. I don't know if it was the same one - but it could have been.Quote from: Seekonk on May 27, 2017, 08:59:47 amI hear you.To fire this one up once power was turned on, you had to manually key the bootstrap routine via toggle switches on the front panel. The address and data were written on a piece of paper stuck near the switches. Set the switches then toggle the Load Address switch, then set the switches for the instructions and load them, one at a time. At the end you toggled a switch that started execution ... and you prayed the teletype would print a character (an asterisk, I think) to indicate it was alive! If you didn't get it - you started all over again.Aside from the obligatory TTY, this system had a high speed paper tape punch, which really chewed through the tape. From memory, it would do something like a metre or so per second. This was obviously a commercial product ... unlike the high speed paper tape reader...!This was a true tinker creation. First we start with a paper guide, under which was fitted a sprocket drive connected to a stepper motor mounted to one side. The opto receptors were underneath somewhere, but the real touch of class was the light source. Six inches or so above the tape path, it consisted of a light globe in a holder clamped to a stand that could have been 'repurposed' from the chemistry lab. The whole thing just sat on a table, without a case - which was rather useful as it turned out. Sometimes when you read a tape, it didn't register the end of file - so you waved your hand (with spread fingers) back and forth until you heard the beepThe real magic, though, was that this system not only had a screen and keyboard - it had a storage vector graphics screen as well!!Ah - that was a real nerd fest.

author: tggzzz
author_rank: Super Contributor
timestamp: May 27, 2017, 10:29:59 am
content: Quote from: Brumby on May 27, 2017, 10:06:44 amA commercial paper tape reader would read at 1000cps, and stop within one characterWhen running, the tape flew about 2m in a big arc into a large bin. You really didn't want to get your fingers anywhere near a moving paper tape.

author: coppice
author_rank: Super Contributor
timestamp: May 27, 2017, 12:02:03 pm
content: Quote from: Seekonk on May 27, 2017, 08:59:47 amThat was always such fun when the machine developed a problem that kept corrupting the section of core containing the bootloader.

author: retrolefty
author_rank: Super Contributor
timestamp: May 27, 2017, 01:31:19 pm
content: Quote from: coppice on May 27, 2017, 12:02:03 pmNope, on the minicomputer I field serviced for, the bootloader was always overwritten, so the 16 word bootloader always had to be fingered in via front panel switches. No problem, it was memorized so it took me about 20 secs to enter and hit run.

author: coppice
author_rank: Super Contributor
timestamp: May 27, 2017, 01:58:58 pm
content: Quote from: retrolefty on May 27, 2017, 01:31:19 pmOn the Novas, Perkin Elmers, DECs and others I've had to get up from scratch by entering the boot loader, it was a lot more than 16 words, but normally survived between reboots.

author: rstofer
author_rank: Super Contributor
timestamp: May 27, 2017, 04:26:07 pm
content: In grad school ('75-76), I used an ASR33 teletype connected to a DataGeneral system when I was on the campus. At home I dialed in using a glass teletype (ADM3) and acoustic coupler at 110 Baud (later I got up to the smoking speed of 300 Baud).I had to write a tiny Algol compiler using DataGeneral Basic (because that is what I had access to) and it wasn't pretty. Up to a point, it worked well.At the end, the Dean told me that I was the biggest single user of computer time on campus. I didn't tell them that most of that time was spent playing StarTrek.The other grim project was writing an 8080 Assembler in PL/I (which I kind of liked) but I had to run it on the business 360-45, time available. That didn't work well either but the assembler turned out fine. I needed the assembler because my Altair 8800 didn't have much in the way of software. That changed rather quickly as Basic, C, PL/I and Pascal became available over the next 5 years.I started programming in Fortran on an IBM1130 in '70. Something like this:http://computermuseum.informatik.uni-stuttgart.de/dev/ibm1130/ibm1130.htmlThe system, along with the IBM Electronic Circuit Analysis Program (ECAP) was quite helpful getting me through undergrad (EE). I now have an FPGA implementation of the entire system including the plotter and it runs all of the original IBM software including the 27 pass Fortran compiler.Good times!

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: May 28, 2017, 04:40:11 am
content: I went through the co-op program at my university which meant that I was in class every other four months and out to work the rest of the time. Once, in 1973 or 1974 I spent a work term at the mapping branch of the Department of Energy, Mines and Resources ostensibly as a lowly draughtsman on a gov.-sponsored make-work program. It was pretty boring for the first couple of weeks when I happened to mention to my boss that I had some experience with a PDP-8.Holy cow, I never saw him move so fast as on that day. He said that they had one they would take on field trips to the arctic when they would check the location of the benchmark stations against the reigning navigation tool of the day which was the Omega system of high-power VLF transmitters. He said that they needed some error analyses software developed and no one else had any idea how to turn the damn thing on let alone write software for it.So he set me up with my own machine, paper tape reader, punch, and TTY in a hastily organized room about 12' x 12' and all the paper tape I could eat. So for the next 3 1/2 months I was monarch of my own computer domain and a minor VIP on that floor. I finished the project, complete with extensive instructions for use by the time I had to leave but I never got any feedback about its use in the field.

author: ebclr
author_rank: Super Contributor
timestamp: May 28, 2017, 05:57:39 am
content: I learned with this amazing machine

author: brucehoult
author_rank: Super Contributor
timestamp: May 28, 2017, 09:25:56 am
content: Quote from: ebclr on May 28, 2017, 05:57:39 amI've never seen one naked, but I'm guessing that's a ZX80.

author: CJay
author_rank: Super Contributor
timestamp: May 28, 2017, 10:52:55 am
content: Quote from: brucehoult on May 28, 2017, 09:25:56 amThat's the beasty, there was one on a window ledge of a wooden outbuilding at Jodrell Bank with the cases next to it for a while, still regret not taking the one I was offered but I may get the gumption to build a clone some day...

author: ebclr
author_rank: Super Contributor
timestamp: May 28, 2017, 05:09:01 pm
content: If you are serious about making the clone this may help youhttps://echorod.home.xs4all.nl/zx/wilfs_zx97_article.htm

author: xrunner
author_rank: Super Contributor
timestamp: May 28, 2017, 05:25:15 pm
content: Quote from: Housedad on May 26, 2017, 06:28:53 amI guess I'll admit it - and here's my lab book and some of my programming from university. You can see the date for yourself.

author: boffin
author_rank: Unknown
timestamp: May 28, 2017, 05:42:43 pm
content: Quote from: xrunner on May 28, 2017, 05:25:15 pmImmediately my brain says "Hey that was printed on an LA36 DECwriter" (although we mostly had LA120s )Also, my aunts' husband taught electroncs at Algonquin around that time, quite likely you had him as a teacher

author: retrolefty
author_rank: Super Contributor
timestamp: May 28, 2017, 06:47:16 pm
content: Quote from: boffin on May 28, 2017, 05:42:43 pmCool picture. We use to have a ton of LA-36s at the refinery I worked at. We found a 3rd party retrokit that would speed up the LA-36 to LA-120 speed for a lot cheaper then replacement. Those were very reliable printers and were the first generation of great I/O gear that DEC made along with VT-100. Prior to that I didn't think much of DEC I/O gear although their processors were always good.

author: Housedad
author_rank: Frequent Contributor
timestamp: May 28, 2017, 11:06:18 pm
content: Wow, in the late 70's, I would drive up to Northeast Philly to the Heathkit store on Roosevelt Blvd and when I walked in, they had a H8 computer with a DeCwriter on display. I remember spending most of my time (When they had it there) drooling and fawning over the DeCwriter and wishing I was rich.I Loved going to the Heathkit store!!! Pure candyland!

author: Housedad
author_rank: Frequent Contributor
timestamp: May 28, 2017, 11:18:59 pm
content: OT, but from near the same era. For some reason, I always thought that this Radio Shack computer table from 1978 was the coolest looking computer table that I have ever seen.

author: digsys
author_rank: Unknown
timestamp: May 29, 2017, 12:11:56 am
content: Yup, old memories. Adelaide University 1970-1972ish+ As computer geeks, we were given 5.0 Secs (10.0?) of processing time FREE a week? That was quite a lot as it wascharged out to industry at $20 a Sec back then. I had an awesome short term stint claning valve pins.