VCF East X: Minicomputing With The Raspberry Pi

April 19, 2015 by Brian Benchoff 9 Comments

The Vintage Computer Festival in Wall, New Jersey doesn’t just attract locals; [Oscar] came all the way from Switzerland to show off his PiDP-8/I. It’s a miniature minicomputer, emulated in SimH, with blinkenlights and toggle switches mounted to a Raspberry Pi Hat.

Although the PiDP-8 is emulating a machine with thousands of discrete transistors, the design is exceptionally simple. On the board is 92 LEDs, a bunch of diodes, 26 toggle switches, a driver chip, and that’s about it. All the multiplexing for the switches and LEDs is taken care of in software. On the Raspberry Pi side, [Oscar] is able to run FOCAL, OS/8, and, like a normal-sized PDP-8, can toggle in programs manually.

Instead of having connecting to the ribbon cables coming out of RK01 disk drives and DECtapes, [Oscar] is emulating those too. All the files that would reside on old Digital storage mediums are now stuffed into USB thumb drives. A USB hub is plugged into the Pi, and when one of these USB disk packs is plugged into the hub, loading an operating system or a program is just a matter of flicking a few toggle switches.

[Oscar] has been working hard to turn the PiDP-8 into a kit, and the word around the booths is that this will happen sometime this summer. The expected price for this kit is very interesting: somewhere between $100 and $150 USD. For that price, we’d expect someone to rig up an Arduino-based paper tape reader very quickly, perhaps this afternoon.

More pics and a video of the PiDP-8/I below.
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Retro Edition: VCF East X This Weekend

April 15, 2015 by Brian Benchoff 13 Comments

It’s mid-April and time once again for the Vintage Computer Festival East X. The X means 10. It’s a three-day weekend full of interesting people, cool tech, and computers you’ve only heard about. We’ll be there all three days, and if you’re in New York or are unable to pump your own gas (Oregon excluded), it’s a great way to spend the weekend.

The sessions for this Friday will include everything from chiptunes to retr0bright to emulating vintage computers on FPGAs. Sessions of note include our own [Bil Herd] giving a talk on system architecture. Think of this as a bunch of engineers in a room with a whiteboard. How could you not have fun with that. There will also be the first meeting of the Quarternet committee, headed up by [Jim Brain]. This session will be a discussion of implementing a vintage networking protocol across different models and different brands of vintage computers. Confused? It’s a, “two-bit solution for an eight-bit world.” That’s all we know, and I’m pretty sure that’s all anyone knows. It will be interesting.

Saturday and Sunday will feature an incredible number of exhibits that includes everything from Atari 8-bits, Hollerith cards, mainframes, an amateur radio station (KC1CKV) and somehow a Fairlight CMI. Since this is the 50th anniversary of the PDP-8, there will be a few of these ancient machines on display. A freshly restored Straight-8 will be up and working, as will an incredible emulation from hackaday.io.

Just because there are exhibits doesn’t mean the talks end on Friday. On Saturday the guest speaker will be [Brian Kernighan], the guy who literally wrote the book on C. Sunday will feature [Bob Frankston], co-developer of VisiCalc. There will be very important people here all weekend.

Even if vintage computers aren’t your thing, there’s still plenty of stuff to see at the venue. The InfoAge science center has technological curiosities stretching back a century, and recently they’ve rehabbed an old satellite dish and turned it into a radio telescope. Registration happens here, and if the last few paragraphs haven’t sold you on the event, you can check out [The Guru Meditation]’s VCF preview video below. We will, of course, be posting a lot of stuff from the event.

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Hackaday Retro Edition: Remaking The PDP 8/I With A Raspberry Pi

March 26, 2015 by Brian Benchoff 48 Comments

[Oscar] really likes the PDP-8s, with the extremely old school PDP-8/I being his favorite. If you haven’t checked the price on these recently, getting a real PDP-8/I is nigh impossible. However, after assembling a KIM-1 clone kit, an idea struck: what about building a modern PDP-8/I replica that looks like the real thing, but is powered by modern hardware. This would be fairly cheap to build, and has the added bonus of not weighing several hundred pounds.

The PiDP-8 is [Oscar]’s project to replicate the hardware of the 8/I in a modern format. Instead of hundreds of Flip Chips, this PDP-8 is powered by a Raspberry Pi running the SIMH emulator. The 40-pin GPIO connector on the Pi is broken out to 92 LEDs and 26 toggle switches on a large PCB. This setup gets [Oscar] a reasonable facsimile of the PDP-8/I, but he’s also going for looks too. He created an acrylic panel with artwork copied from an original 8/I that mounts to the PCB and gives the entire project that beautiful late 60s / early 70s brown with harvest gold accent color scheme.

Since this emulated PDP-8/I is running on entirely new hardware, it doesn’t make much sense to haul out disk drives as big as a small child, tape drives, and paper tape readers. Instead, [Oscar] is putting everything on USB sticks. It’s a great solution to the problem of moving around files that are a few kilowords in size.

[Oscar] says he’ll be bringing his PiDP to the Vintage Computer Festival East X in Wall, NJ, April 17-19. We’ll be there, and I’ve already offered [Oscar] the use of a VT-100 terminal. If you’re in the area, you should come to this event. It’s guaranteed to be an awesome event and you’re sure to have a great time. Since this is the 50th anniversary of the introduction of the PDP-8, there will be a half-dozen original PDP-8s set up, including a newly refurbished Straight-8 that came out of the RESISTORS.

Oh, if anyone knows how to connect a Pi to a VT100 (technically a 103), leave a note in the comments. Does it need the RTS/CTS?

Arduino Reads Punch Cards

January 17, 2015 by Adam Fabio 14 Comments

Punch cards were a standard form of program and data storage for decades, but you’d never know it by looking around today. Card punches and even readers are becoming rare and expensive. Sometimes it takes a bit of hacking [YouTube link] to get that old iron running again!

[Antiquekid3] managed to score an old punch card reader on Ebay, but didn’t have a way to interface with it. The reader turned out to be a Documation M-1000-L. After a bit of searching, [Antiquekid3] managed to find the manual [PDF link] on BitSavers. It turns out that the Documation reader used a discrete output for each row of data. One would think the Documation reader would be a perfect fit for the PDP-8 lurking in the background of [Antiquekid3’s] video, but unfortunately the ‘8 lacks the necessary OMNIBUS card to interface with a reader.

Undaunted, [Antiquekid3] threw some modern hardware into the mix, and used an Arduino Uno as a Documation to Serial interface. The Arduino had plenty of I/O to wire up with the card reader’s interface. It also had a serial interface which made outputting data a snap. The ATmega328 even had enough power to translate each card from one of IBM’s many keypunch formats to serial.

[Antiquekid3’s] test deck of cards turned out to be a floating point data set. Plotting the data with a spreadsheet results in a nice linear set of data points. Of course, no one knows what the data is supposed to mean! Want more punch card goodness? Check out this tweeting punch card reader, or this Arduino based reader which uses LEGO and a digital camera to coax the data from the paper.

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