A PDP-11 On A Chip

August 22, 2016 by Jenny List 47 Comments

If you entered the world of professional computing sometime in the 1960s or 1970s there is a high probability that you would have found yourself working on a minicomputer. These were a class of computer smaller than the colossal mainframes of the day, with a price tag that put them within the range of medium-sized companies and institutions rather than large corporations or government-funded entities. Physically they were not small machines, but compared to the mainframes they did not require a special building to house them, or a high-power electrical supply.

A PDP-11 at The National Museum Of Computing, Bletchley, UK.

One of the most prominent among the suppliers of minicomputers was Digital Equipment Corporation, otherwise known as DEC. Their PDP line of machines dominated the market, and can be found in the ancestry of many of the things we take for granted today. The first UNIX development in 1969 for instance was performed on a DEC PDP-7.

DEC’s flagship product line of the 1970s was the 16-bit PDP-11 series, launched in 1970 and continuing in production until sometime in the late 1990s. Huge numbers of these machines were sold, and it is likely that nearly all adults reading this have at some time or other encountered one at work even if we are unaware that the supermarket till receipt, invoice, or doctor’s appointment slip in our hand was processed on it.

During that over-20-year lifespan of course DEC did not retain the 74 logic based architecture of the earliest model. Successive PDP-11 generations featured ever greater integration of their processor, culminating by the 1980s in the J-11, a CMOS microprocessor implementation of a PDP-11/70. This took the form of two integrated circuits mounted on a large 60-pin DIP ceramic wafer. It was one of these devices that came the way of [bhilpert], and instead of retaining it as a curio he decided to see if he could make it work.

The PDP-11 processors had a useful feature: a debugging console built into their hardware. This means that it should be a relatively simple task to bring up a PDP-11 processor like the J-11 without providing the rest of the PDP-11 to support it, and it was this task that he set about performing. Providing a 6402 UART at the address expected of the console with a bit of 74 glue logic, a bit more 74 for an address latch, and a couple of 6264 8K by 8 RAM chips gave him a very simple but functional PDP-11 on a breadboard. He found it would run with a clock speed as high as 11MHz, but baulked at a 14MHz crystal. He suggests that the breadboard layout may be responsible for this. Hand-keying a couple of test programs, he was able to demonstrate it working.

We’ve seen a lot of the PDP-11 on these pages over the years. Of note are a restoration of a PDP-11/04, this faithful reproduction of a PDP-11 panel emulated with the help of a Raspberry Pi, and an entire PDP-11 emulated on an AVR microcontroller. We have indeed come a long way.

Thanks [BigEd] for the tip.

A Tech That Didn’t Make It: Sound On Stainless Steel Wire

August 16, 2016 by Gerrit Coetzee 62 Comments

For a brief period in the 1940’s it might have been possible for a young enamored soul to hand his hopeful a romantic mix-spool of wire. This was right before the magnetic tape recorder and its derivatives came into full swing and dominated the industry thoroughly until the advent of the compact disk and under a hundred kilogram hard disk drives. [Techmoan] tells us all about it in this video.

The device works as one would expect, but it still sounds a little crazy. Take a ridiculously long spool of steel wire the size of a human hair(a 1 hour spool was 2.2km of wire), wind that through a recording head at high speed, magnetize the wire, and spool it onto a receiving spool.

If you’re really lucky the wire won’t dramatically break causing an irreversible tangle of wire. At that point you can reverse the process and hear the recorded sound. As [Techmoan] shows, the sound can best be described as… almost okay. Considering that its chief competition at the time was sound carved into expensive aluminum acetate plates, this wasn’t the worst.

The wire recorder lived on for a few more years in niche applications such as airplane black boxes. It finally died, but it does sound like a really fun couple-of-weekends project to try and build one. Make sure and take good pictures and send it in if any of you do.

Continue reading “A Tech That Didn’t Make It: Sound On Stainless Steel Wire” →

Retrofitted Retro Radio

August 13, 2016 by Bryan Cockfield 22 Comments

In a world full of products that are only used for a brief time and then discarded, it gives a lot of us solace to know that there was a time when furniture was made out of solid wood and not particle board, or when coffee makers were made out of metal and not plastic. It’s hard to say exactly what precipitated the change to our one-time-use culture, but in the meantime there are projects that serve to re-purpose those old, durable products from another time so that they can stay relevant in today’s ever-changing world. [Jose]’s new old radio is a great example of this style of hack.

[Jose] had a 1970s-era single-speaker radio that he found in a thrift store. The first thought that he had to get the aesthetically pleasing radio working again was to install a Bluetooth receiver into the radio’s amplifier. This proved to be too time-consuming of a task, and [Jose] decided to drive the Bluetooth module off of the power circuit for the light bulb. He built a 6V AC to 4.2V DC circuit, swapped over the speaker cable, and started listening to his tunes. The modifications he made aren’t destructive, either. If he wants, he will be able to reconnect the original (and still functional) circuitry back to the speaker and pretend he’s back in 1970.

While this isn’t the most intricate hack we’ve ever featured, it’s always refreshing to see someone get use out of an old piece of technology rather than send it off to the landfill with all of our Pentium IIs or last year’s IKEA shelves that have already fallen apart. And even if the 70s aren’t your era of choice, perhaps something newer will inspire you to bust a move.

Hacking When It Counts: Spy Radios

August 12, 2016 by Dan Maloney 33 Comments

World War II can be thought of as the first electronic war. Radio technology was firmly established commercially by the late 1930s and poised to make huge contributions to the prosecution of the war on all sides. Radio was rapidly adopted into the battlefield, which led to advancements in miniaturization and ruggedization of previously bulky and fragile vacuum tube gear. Radios were soon being used for everything from coordinating battlefield units to detonating anti-aircraft artillery shells.

But it was not just the battlefields of WWII that benefitted from radio technology. From apartments in Berlin to farmhouses in France, covert agents toiled away over sophisticated transceivers, keying in coded messages and listening for instructions. Spy radios were key clandestine assets, both during the war and later during the Cold War. Continue reading “Hacking When It Counts: Spy Radios” →

Commodore PET Mods At VCF West 2016

August 8, 2016 by Sonya Vasquez 24 Comments

Here at the Vintage Computer Festival, we’ve found oodles of odds and ends from the past. Some, however, have gotten a modern twist like [bitfixer’s] recent Commodore PET project upgrades.

First off is [bitfixer’s] Augmented Reality upgrade. By the power of two iPhones and one raspberry Pi, the user dons a Google-Cardboard-esque heads-up-display and can visualize a 3D, ASCII rendering of the world before them. Not only does this view show up in the HUD, however, it’s also streamed to a Raspberry Pi whch then serializes it info a video display on the Commodore PET.

28191391174_7186b4758d_z — TRON Legacy, can you tell??

This hack builds on some of [bitfixer’s] prior work getting ASCII video streaming up-and running. Of course, the memory on the Commodore PET is nowhere near capable of being able to process these images. In fact, streaming and storing the video data onto the PET’s memory would fill it up in under one second! Instead, [bitfixer] relies on some preprocessing thanks to the far-more-powerful (by comparison) Raspberry Pi and iPhone processors that are capturing the images.

Next off is [bitfixer’s] full-color video display on the same Commodore PET. Again, leveraging another RaspPi to encode and reduce the video to bitmap images, the Commodore PET simple grabs these images and streams them to the screen as fast as possible–at a beloved 5.8 frames per second.

Vegapin: A Beautiful Virtual Pinball Machine

August 7, 2016 by Elliot Williams 7 Comments

One click on the wrong YouTube link, and one sleepless night after being introduced to virtual pinball, and [Sascha Rossier], aka Swiss hip-hop rapper [Der Lügner], was at work on his own design. You can watch the plans, and the build progress on [Sascha]’s project diary (in German, translated here). The awesome case, huge monitor serving as the playfield, bump and tilt sensors make this a droolworthy device.

We also learned how to say “greebles” in Swiss-German: “greebles“. And there are greebles galore in this build. [Sascha]’s 3D printer was working overtime churning out not only fan ducts for the computer that lives inside the case, but also dia-de-los-muertos themed foot brackets and all sorts of loudspeaker covers and dinosaur accoutrements. This is clearly a labor of love. (And [Sascha] wrote us back about the date in the name: it’s when he and his girlfriend met 20 years ago, playing pinball nonetheless!)

Head off to [Sascha]’s website and check it out. All of the details are there, from the mechanical design to the part selection. This is probably the most elaborate virtual pinball build we’ve seen, but it’s not the only one. Heck, we’ve even seen a virtual machine built into a real pinball machine’s case. But never before have we seen one with so darn many greebles.

Refurbishing Six Commodore 64s In Parallel

August 7, 2016 by Gerrit Coetzee 12 Comments

[Drygol] found himself with six Commodore 64’s in various states of disrepair. Because batch work is often more efficient, he detailed the process of restoring all of them in parallel in this one-, two-, three-part series.

The first step was to whiten the cases. Old cases turn yellow from the degradation of the fire retardant additives in the plastic. The proven method to fix this is with a paste called Retr0bright. [Drygol] used hair bleaching paste which is very similar. The cases came out nicely whitened from their treatment.

Next he repaired the keyboard PCB and whitened the keys as well. Drinking was involved, but it all came out okay. The circuit boards were cleaned and inspected. There were a few corroded spots, broken chips, and bad solder joints to be repaired. A few common mods were also installed.

In the final part of the series two of the C64s have SD cards installed into them. A few interesting fixes were done to repair broken plastics. Lastly the two worst cases were painted. In the end [Drygol] found himself with six perfectly working and attractive C64s. Who know’s what he’ll do with them, but we all know that was not the point.