DEC

25 Articles

Flip-Chip KiCad Templates

November 7, 2021 by 13 Comments

We like retro-computing and we like open source standards that allow easy project sharing. Vintage DEC computer enthusiast [Jay Logue] combines both of these in his recent project on GitHub, where he shares several KiCad templates for making your own Flip-Chip modules. Although named after the semiconductor packaging technique we are familiar with today, DEC Flip-Chips were introduced in 1964 as a modular electronics packaging system. These were used in many of DEC’s Programmable Data Processor (PDP) computers, beginning with the PDP-8 in 1965. DEC also had a Digital Laboratory Module family, which was a roll-your-own custom electronic system. The 1968 Digital Logic Handbook shows the available modules, and has the look and feel of the TTL Cookbook book which would come along six years later.

Flip-Chips came in a variety of sizes over the years: single-, double-, and quad-, and hex-height boards having standard- and extended-length. The PCB’s have 18 gold-plated fingers on one edge, later extended to 36 fingers double-sided, which plug into a backplane. Interconnections were typically wire-wrapped. A single height board is 127 x 62 mm (5 x 2-7/16 inches) with a labeled extractor bracket on one end. [Jay]’s repository has templates for five of the most popular variations, and making other sizes should be straightforward using these templates as a starting point.

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Inside A DEC Hard Drive

April 19, 2021 by 40 Comments

A lot of technology from the not-so-distant past doesn’t resemble modern versions very much. For a case in point, look at the DEC RS08 disk drive meant to pair with a circa 1970 PDP-8. Paired with an RF08 controller, this was state of the art, holding 262K 12-bit words with a blistering access speed of almost 63K/second unless you were plugged into 50Hz AC when it was closer to 50K/second. [Uniservo] had the disk unit, but not the controller. Someone else had a controller, but no disk drive. So [Uniservo] is shipping the disk to its new owner in a move worthy of a Reeses’ Peanutbutter Cup. The problem? The disk is super fragile and shipping is risky, so he decided to remove the platter for separate packing. Good thing for us, because we get a peek inside.

The nickel-cobalt platter looks like a thick LP record with heads underneath. As you might guess from the data transfer specification, the motor was just a common AC motor that rotated the platter against the head.

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Reproduction 1960s Computer Trainer Really Pushes Our Buttons

June 28, 2020 by 13 Comments

If you were selling computers in the early 1960s you faced a few problems, chief among them was convincing people to buy the fantastically expensive machines. But you also needed to develop an engineering force to build and maintain said machines. And in a world where most of the electrical engineers had cut their teeth on analog circuits built with vacuum tubes, that was no easy feat.

To ease the transition and develop some talent, Digital Equipment Corporation went all out with devices like the DEC H-500 Computer Lab, which retrocomputing wizard [Michael Gardi] is currently building a reproduction of. DEC’s idea was to provide a selection of logic gates, flip flops, and other elements of digital electronics that could be hooked together into more complicated circuits. We can practically see the young engineers in their white short-sleeve shirts and skinny ties laboring over the H-500 in a lab somewhere.

[Mike] is fortunate enough to have have access to an original H-500, but he wants anyone to be able to build one. His project page and the Instructables post go into great detail on how he made everything from the front panel to the banana plug jacks; almost everything in the build aside from the wood frame is custom 3D printed to mimic the original as much as possible. But the pièce de résistance is those delicious, butterscotch-colored DEC rocker switches. Taking some cues from custom switches he had previously built, he used reed switches and magnets to outfit the 3D printed rockers and make them look and feel like the originals. We can’t wait for the full PDP build.

Hats off to [Mike] for another stunning reproduction from the early years of the computer age. Be sure to check out his MiniVac 601 trainer, the Digi-Comp 1 mechanical computer, and the paperclip computer. If you’d like to pick [Mike’s] brain about this or any of his other incredible projects, he’ll be joining us for a Hack Chat in August.

Thanks to [Granzeier] for the tip!

An Entire PDP-11 On Your Bench

August 24, 2019 by 25 Comments
A PDP-11 at The National Museum Of Computing, Bletchley, UK.
A PDP-11 at The National Museum Of Computing, Bletchley, UK.

The DEC PDP series of minicomputers occupy a special place in computing history for us, because as the workhorses of commercial computing from the 1960s through to some time in the 1990s they provided the bedrock upon which so many of the computing technologies we take for granted today were built. If we think of any PDP, the chances are we’ll be imagining fridge-sized units with panels of blinkenlights that have become iconic in their own right. But that wasn’t the sum of PDP hardware, for at the end of the series of machines there were produced PDP-11s containing what had previously needed those fridge-sized units on a single chip-sized module. [Peter Schranz] had one of these modules, a DCJ11 that he’d salvaged in the 1990s, and he set to with it in making a modern desktop version of a PDP-11.

The PDP-11/hack is a PDP-11 as a set of daughter cards on a lightly modified Q-bus backplane. The DCJ11 and its memory sit on one, an emulated disc controller on another, and finally a multifunction board brings together clock and serial functions. Where the original would have had acres of 74 logic the PDP-11/hack uses more modern CPLDs and microcontrollers to provide glue logic and to emulate now-obsolete components. Given a serial terminal it will boot and run PDP operating systems and software, though it lacks a set of blinkenlights to display its status.

This isn’t the first PDP-11 using this chip we’ve shown you.

Getting Started With Blinking Lights On Old Iron

August 10, 2017 by 29 Comments

If you ever go to a computer history museum, you’ll be struck by how bland most modern computers look. Prior to 1980 computers had lights and switches, and sometimes dials and meters. Some had switchboard-like wiring panels and some even had oscilloscope-like displays. There’s something about a machine with all those switches and lights and displays that gets your hacker juices flowing. Have you ever wanted to get started in retrocomputing? Is it difficult? Do you need a lot of money? That depends on what your goals are.

There are at least three ways you can go about participating in retrocomputing: You can pony up the money to buy actual antique computers, you can build or buy old computers recreated with anywhere from zero to one hundred percent of period-authentic components, or you can experiment with emulators that run on a modern computer. As a hybrid of the second and third option there are also emulations in FPGAs.

You can see that the first option can be very expensive and you will probably have to develop a lot of repair and restoration skills. Watching [Mattis Lind] twiddle the bits on an actual PDP-8 in the clip above is great, but you’ll need to work up to it. The two techniques which get you going without the original hardware don’t have to break the bank or even cost anything presuming you already have a PC.

Although some sneer at emulation, for some machines it is almost the only way to go. You couldn’t buy the original EDSAC, for example. It is also a good way to get started without a lot of expense or risk. But regardless of how you do it, there’s one thing in common: you have to know how to operate the thing.

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The PDP-1: The Machine That Started Hacker Culture

June 27, 2017 by 32 Comments

One of my bucket list destinations is the Computer History Museum in Mountain View, California — I know, I aim high. I’d be chagrined to realize that my life has spanned a fair fraction of the Information Age, but I think I’d get a kick out of seeing the old machines, some of which I’ve actually laid hands on. But the machines I’d most like to see are the ones that predate me, and the ones that contributed to the birth of the hacker culture in which I and a lot of Hackaday regulars came of age.

If you were to trace hacker culture back to its beginning, chances are pretty good that the machine you’d find at the root of it all is the Digital Equipment Corporation’s PDP-1. That’s a tall claim for a machine that was introduced in 1959 and only sold 53 units, compared to contemporary offerings from IBM that sold tens of thousands of units. And it’s true that the leading edge of the explosion of digital computing in the late 50s and early 60s was mainly occupied by “big iron” machines, and that mainframes did a lot to establish the foundations for all the advances that were to come.

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A Modern Day PDP-11 Front End

April 26, 2017 by 26 Comments

Hands up if you feel your spiritual home is in front of a terminal with a “DIGITAL” logo on it.  It’s a name that has long ago been subsumed into first Compaq and then by extension HP, but it’s one with a lot of history when it comes to computing.

From the start of the electronic computing age, there were the computers we’d probably now describe as mainframes. Big computers that cost the GDP of a small country, filled an entire floor of a building, and could only be found in government departments, universities, and large companies. By the 1960s, the technologies existed to build computers that broke this mould, could be bought within the budget of a smaller organisation, and for which you didn’t need a huge air-conditioned basement to house. These so-called minicomputers were the great revolution of that era because they bought the fruits of computing into everyday business, and probably the most successful of the companies that produced them was the Maynard, Massachusetts-based Digital Equipment Corporation, or DEC.

DEC produced a succession of minicomputers in their PDP line, of which the most successful was their PDP-11 series. These were 16-bit minicomputers that remained in their product line from their launch in 1970 through to the early 1990s, and were available in a succession of configurations and physical form factors. The famous view of a PDP-11 is of a set of floor-to-ceiling racks, but there were also standalone terminal models, and desktop models. One of these, a PDP-11/03 from 1975, has come into the hands of [Joerg], and he’s used it to craft his LSIbox, the PDP11/03 card frame packaged with a BeagleBone for access via a modern-day interface. It’s a build in the vein of modern tube audio amplifiers that feature the retro hardware on the top of their cases, the card frame is exposed as a feature on top of a white case that is featureless except for a genuine PDP-11/03 front panel.

You might ask why anyone would do this in order to run PDP-11 software when the BeagleBone could almost certainly emulate the vintage hardware much faster than the real thing. But to take that view is to miss the point; the PDP-11 series are a seminal part of computing history, and to have genuine PDP-11 hardware on your desk is quite an achievement.

We’ve shown you a few PDP-11 projects in the past. There was this minimalist PDP-11 implementation using one of the later integrated PDP-11 processors, and we’ve seen a faithful reproduction of an earlier PDP-11 front panel powered by a Raspberry Pi.