PDP-11

[Mark H. Shin]

I have been a fan of the DEC brand for some time ... RT-11 was the OS for teaching assembly language at the time...

I discovered that another fan created an Raspberry Pi project of the front panel of the DEC PDP-11 mini computer.

Obsolescence Guaranteed

I also discovered the work of the Paul Nankervis who has created a faithful emulation of the PDP-11/70 and PDP-11/45 mini computer in Javascript.

In addition he has compiled a collection of original bootable disk/tape images of the operating systems for the PDP-11.

This inspired me to create an Electron application based on this work...



The GitHub repository can be found here.

There are instructions on building the application available on that page. Any questions can be forwarded to me via PM...

I should clarify that the repository is a scaffold for a stand-alone Electron application project, and a download of a ZIP archive from Paul Nankervis' website will be required.

The instructions of the repository should be clear...

Please visit the respository and follow the instructions to build your very own desktop version...

[bbergman]

I bought this exact kit as a physical Tindie kit over the pandemic to keep me occupied, but I have yet to finish it. I am really interested in seeing it finished. I can't wait to run RSTS/E or VMS on it!

Keep us apprised!

[lmamakos]

I've had a PiDP-11 for a number of years now, getting one early on as I anxiously await the kits to start shipping! What a blast from the past; I run 2.11BSD UNIX on mine, mostly. I also found a rather nice PDP-11 FORTH that I can also boot into.

This hardware reproduction of the front panel really was quite the journey if you go back to the early mailing list. Getting the switch paddles custom manufactured, color matching the plastics, and adventures in learning injection molding for the white bezel. Not only is this a wonderful reproduction (at two-thirds scale!) of the experience of using a computer like that, but it really is an art piece.

I brought mine into work to demonstrate to those not nearly as "vintage" as me how we booted computers in the old days by entering a bootstrap into memory with the front panel. And who needs some fancy symbolic debugger when you can poke around at will with the lights and swtiches!

The kit is not difficult to assemble; all through-hole parts to solder. Really, the hardest parts are the mechanical aspect - mostly ensuring that all those switches are aligned with each other as you solder them in. There's an alignment guide that comes with the kit just for this purpose.

Sure is nice to have a computer of my own with Blinkenlights as intended.

[KeithB]

You can do a PDP-8, too:
https://spectrum.ieee.org/put-the-classi...your-shelf

But I have trouble believing this line from the article:
"The PDP-8 had just eight machine-code instructions operating on 12-bit words,"

Just 8? I would think the math instructions would take more than that.

[Bill (Smithville NJ)]

(10-28-2022 02:20 PM)KeithB Wrote:  You can do a PDP-8, too:
https://spectrum.ieee.org/put-the-classi...your-shelf

But I have trouble believing this line from the article:
"The PDP-8 had just eight machine-code instructions operating on 12-bit words,"

Just 8? I would think the math instructions would take more than that.

Here's a reference to the instruction set:

PDP-8 Instruction Set

Quote:

Quote:The PDP-8 instruction set is so small that many operations that are usually single instructions on a larger machine must be performed by instruction sequences on the PDP-8. While these are referred to as macros here, the memory resources of the PDP-8 are limited enough that these are usually not coded as given, but rather, carefully folded into other computations.

73
Bill WD9EQD
Smithville, NJ

[Thomas Klemm]

(10-28-2022 02:20 PM)KeithB Wrote:  Just 8? I would think the math instructions would take more than that.

It appears it has 6 MEMORY REFERENCE INSTRUCTIONS and 2 AUGMENTED INSTRUCTIONS:



From: First PDP-8 brochure

[BobVA]

(10-28-2022 02:20 PM)KeithB Wrote:  ...Just 8? I would think the math instructions would take more than that.

The original RISC computer :-)

I built a PiDP-8 kit in 2016 and it's been running more or less continuously ever since. Fun project!

[David Hayden]

(10-28-2022 02:20 PM)KeithB Wrote:  Just 8? I would think the math instructions would take more than that.

Bah... Anything more than ADD is just window dressing.

[KeithB]

I think you need a complement in there somewhere, too. 8^)

It seems to me that each opcode is an instruction, no matter the bit coding.

[Thomas Klemm]

(11-01-2022 01:30 PM)David Hayden Wrote:  Bah... Anything more than ADD is just window dressing.

On x86 all you need is the MOV instruction:




Cf. ONE INSTRUCTION TO RULE THEM ALL: C COMPILER EMITS ONLY MOV

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If you enjoyed this talk you might also like: LambdaLisp - A Lisp Interpreter That Runs on Lambda Calculus

[teenix]

Gwyllym Suter has redesigned the EDUC-8 mini home computer which was based on the PDP-8 back in the 70's and will have complete kits available with more usable memory.

Some info is at this site

[Thomas Klemm]

(11-02-2022 12:32 AM)teenix Wrote:  Some info is at this site

This link is broken.
Fixed it: this site

[teenix]

(11-02-2022 03:52 AM)Thomas Klemm Wrote:  

(11-02-2022 12:32 AM)teenix Wrote:  Some info is at this site

This link is broken.
Fixed it: this site

Oops, was a typo, fixed now.

If anyone is interested in an emulator

Programming one of these is a bit of a mind twister.

[robin48gx]

I made the PDP-11 kit and the PDP-8 kit!
They both work well and the blinking lights look good!