NYC Resistor Gets A PDP-11/34

May 18, 2014 by Adam Fabio 40 Comments

PDP-11/34 NYCR

[Trammel Hudson] and NYC Resistor have gotten their hands on some old computing iron in the form of a PDP-11/34. The PDP-11 is a 16 bit minicomputer made by Digital Equipment Corporation (DEC). Various incarnations of the PDP-11 were sold from the 1970’s all the way into the 1990’s. NYC Resistor’s model is has a label dating it to 1983.

The PDP was found in an old storage unit in the Bronx. Moving several racks of equipment across the city is no small feat, but NYC Resistor members have it done it so many times they’ve got it down to a science.

Once power is applied, a stock PDP won’t actually do anything until the boot loader is keyed in from the CPU front panel. Thankfully this particular PDP-11 had its boot instructions printed on a label on the CPU. NYCR’s machine also includes an M9312 “bootstrap / Unibus terminator” board, which allows the machine to boot at the push of a button.

The team connected the racks, terminals, and drives. Carefully following the instructions, they actually got their PDP to boot up! Their next step is to start reading in some of the old tapes that came with the machine. We’re all waiting with bated breath to see what “digitized monkey brains” contains. Once the machine is fully functional, we hope they get it on the internet and load up The Hackaday Retro Edition.

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Johnny Mnemonic, Broken Columns, And Pinball Repair

May 17, 2014 by Brian Benchoff 13 Comments

johnny

[Quinn Dunki] has come to realize the pinball machines of her youth aren’t the lame games she remembered. They’re actually quite marvelous in terms of electronics, mechanics, engineering and the all important hackability. Wanting to pick up a 90s dot matrix display pinball machine and being a [William Gibson] fan, [Quinn] picked up an old Johnny Mnemonic machine. She’s already looked into replacing the incandescent bulbs with LEDs, and has just wrapped up troubleshooting a broken plasma dot matrix display.

dots The neon dot matrix displays in pinball machines of this era are finicky devices with a lot of stuff that can go wrong. On powering the display up, [Quinn] noticed a few columns on the left side of the display weren’t working. These machines have great diagnostic menus, so running a test that displays a single column at a time revealed two broken columns. However, when a solid fill test was run, all the columns work, save for a few dots in the upper left corner. This is an odd problem to troubleshoot, but after more tests [Quinn] realized dots in column five and six only work iff both adjacent dots in the same row are lit.

The power supply seemed okay, leaving the problem to either a logic problem, or something wrong in the glass. With a meter, [Quinn] deduced there was a short between the two broken columns, and tracing every thing out revealed a problem in the hermetically sealed display filled with noble gasses. A replacement display was ordered.

While [Quinn] was replacing the display, she decided it would be a good time to rehab the almost-but-not-quite out of spec driver board for the display. The power resistors had scorched the PCB, but didn’t damage any traces. Replacing the parts with modern components with a higher power rating brought the board back to spec with components that should last longer than the 20-year-old parts previously inhabiting the driver board.

It was a lot of effort, but now [Quinn] has a brand new display for her pinball machine and is ready to move on to the next phase of her restoration.

C64 MIDI And Flash Cart

April 30, 2014 by Brian Benchoff 12 Comments

Kerberos The SID chip inside the Commodore 64 and 128 is arguably still the gold standard for chip tunes, and the C64 itself still a decent computer for MIDI sequencing. [Frank Buss] realized most of the MIDI cartridges for the Commodore computers are either out of production or severely limited, so he set out to create his own.

Unlike the few Commodore MIDI cartridges that are available, [Frank]’s Kerberos has MIDI In, Out, and Thru, controlled by the 6850 ACIA chip, just like the old 80s interfaces. This allows the Kerberos to interface with the old Sequential Circuits, Passport, and Datel software. He’s offering the Kerberos cart up on a crowdfunding site, so if you’d like to grab your own, have at it.

Because the Kerberos is also a Flash cart, it also ships with some of this software; [Frank] got permission from Steinberg to install their Pro 16 software with the Kerberos. SID Wizard is also pre-loaded on the cart, along with a few other fabulous trackers and sequencers. Of course, there’s no requirement for the Flash portion of the cart to only host MIDI and synth software. You can always upload a few games to the cart over a MIDI interface. Video of the Kerberos below.

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Hackaday Retro Edition: Hackadaying At 300 Baud

April 27, 2014 by Brian Benchoff 15 Comments

SONY DSC

For a bottom of the barrel website like our retro edition, there’s little reason to have a fast Internet connection. Even the fastest hands in the land can barely type faster than 300 baud. The problem with low-speed connections is the overhead involved, as [Pierre] discovered when he dug out an acoustic modem from the ’80s and loaded up our retro site.

While this isn’t the first modem ever made – that’s 1960s tech – but it does operate at the same speed – 300 bits per second, or slower than you reading this sentence. [Pierre] stuck a desk phone into the modem’s cups, plugged it in to a phone line simulator, and connected to a Raspberry Pi equipped with another modem. From there, it was pretty easy to set up a terminal at 300 baud.

A serial connection isn’t a connection to the Internet, however, and at 300 baud, PPP is nearly impossible. The overhead of encapsulating packets is just that high. SLIP is a much better choice to send IP packets over a slow serial connection, but [Pierre]’s mac doesn’t include the proper tools.

[Pierre] ended up using the serial connection between his Mac and Raspi with Zterm. From there, Lynx and Bob’s your uncle.

There’s an unsurprisingly long video of [Pierre] loading up the retro site below, as well an unsurprisingly long video of speedtest.net running at 56k.

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Hackaday Retro Edition: Parallel Port Ethernet

April 16, 2014 by Brian Benchoff 25 Comments

It’s time once again for a roundup of ancient hardware that has successfully loaded our retro edition. Up this time is a completely random and totally not planned roundup of parallel port to Ethernet adapters.

First up is [Tom Moss] with his IBM 5150 – the first ‘IBM Compatible’ home computer, progenitor of the i7 boxxen warming your ankles as you read this. This machine comes standard with a 4.77 MHz 8088 CPU, 8087 FPU, 512k RAM, two 360k 5.25″ floppy drives, and a few very cool additions: an ISA to CompactFlash card adapter, giving [Tom]’s box 4GB of storage.

How is [Tom] connecting to the Internet? A Xircom PE3-10BT Network Adapter. This neat device turns any parallel port into an Ethernet. With a Telnet program, [Tom] was able to connect to a Unix system and use Lynx to browse over to the retro site. He’s yet to get a DOS browser working, but FTP is go, allowing him to download ancient software directly onto his huge CF card.

The next one isn’t exactly vintage, but it does carry the spirit of antiquated hardware onto the web. [Valentin] is using a FleaFPGA and a 186 over at OpenCores. The FPGA board gives him VGA output, an SD card, A PS/2 keyboard, but no options for networking. That’s no problem for [Valentin], as he wired up a Xircom PE3 parallel port to Ethernet adapter. Yes, the same adapter as the 5150 above. [Valentin] says his parallel port hack is a bit of a mess with non-bidirectional and no dedicated IRQ hardware support. It works, though, so we can’t fault him for that.

We’re always looking for people who have loaded our retro edition on old hardware. If you have some outdated hardware sitting in the attic, get it out, load up Hackaday Retro, and send it in.

Pics from [Tom] and [Valentin] below.

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The HellZXchreiber

April 15, 2014 by Brian Benchoff 23 Comments

HellZXschreiber

Hellschreiber – German for ‘light pen’ – was developed in the 20s as a way to transmit text in a way that was much more robust than the teletypes of the time. These devices were used to great effect by the Germans in WWII, and later became popular with wire services and was used until the 80s. The fax machine then happened, and no one really cared about Hellschreiber, save for a few plucky amateur radio enthusiasts.

In the early 90s, a few of these amateur radio enthusiasts realized they could use their personal computers to communicate with this extremely simple protocol that’s also very resilient against interference and weak radio links. [Danjovic] is following in their footsteps by decoding Hellschreiber on an old ZX Spectrum clone.

[Danjovic] tested his code with the sound sample found in the Hallschreiber wiki article and some text generated by Fldigi. Everything works beautifully, an [Dan] can even change the intensity of the text with the volume control – a very useful feature should the HellZXchreiber ever make it out into the field.

Source and image files available for all you strange Speccy fans. Everyone else can check out the videos below.

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The Ancient Greeks Invented Kevlar Over 2 Millennia Ago

April 11, 2014 by James Hobson 53 Comments

In 356-323 B.C. Alexander the Great of Macedon conquered almost the entire known world by military force. Surprisingly, not much is known about how he did it! An ancient and mysterious armor called Linothorax was apparently used by Alexander and his men which may have been one of the reasons for his ever so successful conquest. A group of students at the University of Wisconsin Green Bay (UWGB) have been investigating in detail and making their own version of it.

The problem is this type of armor decomposes naturally over time unlike more solid artifacts of stone and metal — meaning there is no physical proof or evidence of its existence. It has been described in around two dozen pieces of ancient literature and seen in over 700 visuals such as mosaics, sculptures and paintings — but there are no real examples of it. It is made (or thought to be) of many layers of linen glued together, much the same way that Kevlar body armor works.

The cool thing about this project is the students are designing their own Linothorax using authentic fabrics and glues that would have been available in that time period. The samples have been quite successful, surviving sharp arrows, swords, and even swinging axes at it. If this is the secret to Alexander the Great’s success… no wonder!

The group has lots of information on the topic and a few videos — stick around to learn more!

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