Inspired – the first computer I programmed and got me into computers (wipes tears from eye ;-) and Liz – yes I am old enough! However, I don’t think I could remember the boot loader hand key sequence off the top of my head?

Does the Pi pretend it has a tape reader so you can load the old 1/5 user Basic or Fortran.

All we need now is an ASR33 (Liz – you won’t remember that either)?

Great project.
Cheers
Pete

We had one of these running the Animal Food factoy I worked in. It held the recipes and production schedule with a PLC unit controlling the machines in the factory. Ahh the joy of Octal..

Hmm, I used to toggle in the RIM loader, then read in the BIN loader from paper tape.

Awesome project – though a PDP-11 would be more to my taste.

I’ve seen this project before on other web sites but it is nice to see it here.

A minor correction to the blog.

PDP 8’s were not displaced in the “consumer” market because they were never in the consumer market (they were very expensive) although I would be surprised if a few of them didn’t end up in “consumer” hands. They were displaced in the commercial market by the 16 bit PDP 11. At the company were I had my first electronics job in the mid 70’s (Mostek), PDP 11’s were used almost exclusively for testing the semiconductor dynamic RAM memories that they manufactured.

The PDP-8 was hardly the first “non-house sized” commercial computer, The quite successful IBM 1401 and the IBM 1620 (arguably the first scientific/engineering workstation) both came out in the late 1950s.

What DEC accomplished (starting with the PDP-1) was introducing the minicomputer.

Wow, my first hands on experience of computing was on the mighty PDP 8/L (the DEC Lab 8 which had an A to D capability) at the Safety Lab of Vauxhall Motors Millbrook Proving Ground. I can’t remember the RIM loader (Read In Mode?) either but it had to be keyed in every time before we ran the analysis of the safety tests we worked on back in 1971, including the earliest air bag tests. “Our” PDP 8 had the optional 4k bits of extra memory, a full 19″ rack of hand wired copper cores for each bit! Brings tears to my eyes! (and my ears still ring from the paper tape punch which output data for the mainframe analysis…)

I am tempted to buy one of these kits just for nostalgia. My CP/M machine had switches that looked like those. As I remember, I only had 16. You know, 64K is so limited. When I first built it, I had to patch the loader through the switches until I got a new eprom burned. That was while using just a 4k static memory board. When I bought and built and installed a 64k dynamic memory card, the front panel switches would no longer work. The lights and displays worked just fine though. I miss the blinking front panel.

Ugh! This brought back aural flashbacks of impact printers at the school’s remote computer labs.

… Once upon a time, just before that fantastic Summer of ’76, a huge truck wheezed into the playground of my secondary school and a team of Capstan-smoking, tan-lab-coated, ‘technicians’ wheeled huge boxes of equipment up endless flights of stairs and down a maze of twisty little corridors, into the hallowed chambers of Ms Marioni – our beloved Maths Teacher.
From these endless cases, they proceeded to construct a fantastical machine – thousands of switches, millions of lights covers every surface,and miles of thick, writhing, cables spewed from the guts of one box into the gaping innards of another.
With almost no ceremony whatsoever, huge Draculean isolators were slammed shut, Frankenteinian pops and crackles turned the atmosphere blue with electricity – and most of the overhead fluorescent tubes failed spontaneously (many of which were doomed never towork again).
“Right Children, who’s first?” trilled Ms Marioni.
In the surge forward, children were crushed underfoot, their precious bundles of pencil-darkened ‘code cards’ hurled into an airborne shower more reminiscent of an Apollo parade through the streets of New York than a dusty classroom on a hot summer’s afternoon.
The wise amongst us had held back – just enough to keep our footing and – more importantly – our precious pile of cards. Now, it was our turn, more precisely, MY turn.
I carefully placed my 100mm thick bundle of cards in the beast’s hopper, replaced the weighted lid, and was given permission to press the ‘Load’ button. The beast devoured my cards, angrily and noisily. I could only imagine the spinning cogs and gears, the flying rubber belts and some insanely dangerous device that could sharpen an entire pencil into a pile of shavings in less than a second.
What actually then surprised me was the gentle ‘ting’ of a bicycle bell that accompanied a flashing light telling everyone that the machine was ‘ready’.
Everything, and everyone, had gone quiet, save for the low growling of the beast. On command, I carefully pressed the green ‘Run’ button.
The contented growl was barely disturbed as the green ‘Ready’ lamp extinguished – only to be replaced by a dazzlingly bright, horrifyingly red, ‘Error’ lamp.
In abject misery, and with tears of unfathomable grief, knowing that I would now never know what the sum of all the numbers from 1 to 1 million would be, I heard Ms Marioni utter an unforgettable phrase, “Never mind Niall, you can try again next year when the machine comes back again.”

Just a typo : the Wikipedia link directs to the Computer History website.

This brings back memories. I did assembly language programming on the 8/I. I seem to remember that the “I” stood for Integrated Circuit. Previous versions of the PDP-8 used transistors. Ah, the good old days.

great.
I remember seeing blog post about this at the start of the year.

My first job was working on PDP 11/24 while we waited for our set of 11/44 to arrive.
It felt like going back years when we implemented on the customer’s 11/70 in Switzerland and we had to load in the start address via the switched like in the pictures,
I remember doing a sysgen and disabling the “idle lights” sequence because we did not want it to looks like the system was not working hard.

Wow… this brings back memories. I had the opportunity to work for a number of years with the poor cousin of the PDP-8, the PDP-12, which was set up more to provide a number of analog I/O ports, plus had a console screen built into it that could be used to write to and was even possible to address as small dots. I remember writing a lunar landing program on it that showed your decent in stages as you decided how much fuel to convert to thrust. If you crashed with a high-enough impact velocity, a dust cloud of dots appeared at the crash site. :-)

We used it with an ASR-33 teletype and paper tape reader to input data, much of which after pre-processing, was punched out through an interface on an IBM card punch (which certainly was better than doing by hand). Clever setup, eh? Programs were loaded from LINCtapes (go Google that for fun). It ran FOCAL (a BASIC-like language) and Fortran II. As students, we always got the leftover time slots since the faculty and staff had first choice, so many long late nights or early mornings were spent on that dark and light green machine.

It was eventually replaced with a PDP-11/34, but the PDP-12 with its 36-bit architecture (3 x 12-bit bytes) was certainly unique and occupies a memorable spot in my past.

i was a field tech for Digital Equip in the 80s and the PDP * was the Mech i work on and the PDP15 .. all PDP 8s

oh …. I have a PDP 11/83 in the hall … usually with a vase of flowers and a table cloth over it. Visitors have no idea what is lurking below,

The first mini I ever saw was the predecessor, PDP-5. This was used circa 1965 for experiment data collection on the Rutherford Lab Nimrod synchrotron. 4K core storage, paper tape and teletype I/O. Originally no tape drives.
Used 2K for data storage, 2K for operating system (every bit used). On completion an output program overwrote the OS before we could get the data out.

Ah, paper tape. That reminds me: I was a raw graduate. A colleague and I cross-assembled a rudimentary operating system for an 8085 system from Intel-provided source code using a PDP-11/40 cross-assembler written in RSTS-E BASIC. The original BASIC was for an 8080 cross-assembler, so I had to add support for the extra 8085 opcodes, and while I was at it, I also added support for symbolic address arithmetic.

We punched the resulting Intel-Hex-formatted binary to paper tape on an ASR-33 teletype. We had no PROM programmer, so we drove the paper tape, and a blank 2716, to the home office of an associate who had an Intellec MDS equipped with an EPROM programmer.

How did we read in the paper tape? Well, he had concocted a paper tape reader from a ten-channel photodiode array. It was mounted on a block of pine, and used hand-made wire staples to guide the tape across the diode array.Because the drive hole was smaller than the data holes, it worked beautifully as a clock.

This Heath Robinson paper tape reader was wired to a parallel I/O port on the MDS. We “burned” the 2716, plugged it into to our prototype system and away it went. Magic.

(Addendum) It never ceases to amaze me that we used sophisticated minis like the PDP-11 to cross assemble code for simplistic micros like the 6800 and the 8085. The seventies and eighties were a bizarre period of re-expression of existing knowledge in LSI, rather than MSI. I don’t think anything was achieved except to reduce the price and thereby bring the technology within reach of the man on the street. Many of the early microcomputers flaunted (as new) features which had been a part of mainstream computing for many years. Architecturally, compared with many of the mainframes and minis that preceded it, the 8086 was a complete abomination. It wasn’t until micros finally cracked the 32-bit barrier that real progress resumed.

Oh, cool! An 8/I was the first of DEC’s computers I programmed, and the first computer that presented binary version of its internals (the IBM 1620 had instructions that were 12 decimal digits long, two digits of op-code and two addresses of 5 digits each; each of those “digits” was represented by 6 bits of core memory (including parity), but one didn’t think about binary beyond decoding console lights to get the value of digits, and the 1401 was similar but a bit more complicated since each memory location could hold an alphanumeric character).

No, I don’t remember the RIM loader code (though it’s readable in my screen wallpaper). I do remember at least three of the “clear-core” instructions for the IBM 1620 — one used those a LOT more often.

(Um, I mean it’s the first computer *I* used that presented a binary view; obviously there were earlier ones.)

You lot were lucky to have tape. When I were a lad all we had were holes.