Minicomputers on Microcontrollers

PDP

Developed in the very late 60s and through the 70s, the PDP-11 series of minicomputers was quite possibly the single most important computer ever created. The first widely distributed versions of Unix and C were developed on the PDP-11, and it’s hardware influence can be found in everything from the Motorola 68000 to the MSP430.

When [Dave Cheney] saw the recent 8086 simulator written in 4kB of C code, he realized simulating entire computer systems doesn’t actually require a whole lot of resources outside a big chunk of memory. Armed with an Arduino Mega clone, he set out on one of the coolest projects we’ve seen in a while: simulating a PDP-11 on an AVR.

[Dave] used an ATMega2560-powered Arduino Mega clone with an Ethernet module for the hardware of this build. Attached to it is a shield filled up with a pair of RAM chips that expand relatively limited amount of RAM on the ‘Mega.

So far, [Dave] has his simulated system booting Unix V6 off an SD card. For PDP-11 storage, he’s also simulating an RK05 disk drive, a massive 14 inch platter containing 2.5 Megabytes of data. Compared to the original PDP-11/40, [Dave] estimates his machine is about 10 times slower. Still, an original 11/40 system fills multiple server racks, and the most common installations consume several kilowatts of power. The Arduino Mega can fit in a pocket and can be powered over USB.

Future developments for this system include improving the accuracy of the simulator, running more advanced operating systems and the DEC diagnostic programs, and possibly speeding up the simulation. We’d suggest adding some switches and blinkenlights on an additional shield, but that’s just us.

All the code can be found on [Dave]‘s git, with a description of his SPI RAM shield coming shortly.

Controlling blinkenlights with modern computers

A few old timers may remember that once, long ago, computers didn’t require keyboards. The earliest personal computers such as the Altair 8800 and the server rack-sized minicomputers like the PDP-11 could be controlled with a panel filled with switches and lights, giving us the term blinkenlights. Today, most of these machines have been thrown away or locked up in museums and private collections; even if you were to get your hands on one of these control panels, you’ll have a heck of a time doing something useful with one.

Fear not, because [Jörg] has come up with a great way to control these blinkenlights and simulate the computers of yesteryear. He calls his build BlinkenBone, and it’s able to control the blinkenlight panels from dozens of historical computers and simulate every thrown switch and tiny light bulb.

BlinkenBone is a BeagleBone single board Linux computer running the SimH simulator for antique computers. Right now the BlinkenBone is able to simulate the PDP-1, PDP-8, PDP-11, a lot of old IBM machines, the Altair 8800, and even some HP boxes.

Without a BlinkenBone or similar simulation device, the still-surviving control panels for these computers are just pieces of art to hang on a wall. When they’re running a simulation of their original hardware that was long-lost to the scrap yard, they become the useful devices they once were. Also, it’s much easier to appreciate how far technology has come in the last 40 years.

You can check out a short demo of [Jörg] using his BlinkenBone on a PDP-11/40 after the break. Look at those lights go.

[Read more...]

DENCON

dencon

Defcon, the world’s largest hacker convention, is this coming weekend in Las Vegas. While the convention generally focuses on breaking new technology, digital archivist [Jason Scott] has an interesting surprise for attendees this year. With some help from VintageTech, he’ll be assembling a massive den of retro computing machinery. They’ll have fully functional systems like the PDP-11/70 for people to play with. It sure to be one of the more unique things to see at the con.

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