The LPT DAC

September 29, 2014 by Brian Benchoff 41 Comments

About 30 years ago, before every computer had CD quality audio built in, audio cards and chips were technological marvels. MIDI chips, FM synthesis, and synths on a chip reigned supreme but one little device – just a handful of resistors – sounded fantastic. it was the Covox Speech Thing, a simple resistor ladder wired up to the parallel port of a computer that would output 8-bit audio to an external amplifier. [FK] recently built his own Covox (Czech, Google translatrix) with just 18 resistors, and the results sound fantastic.

Instead of fancy chips, the original Covox Speech Thing used the 8 bit parallel port on a PC. Back in the olden days, this was the fastest way to get digital data out of a computer, but since it was digital only, a DAC was required to turn this into audio. A simple resistor ladder was sufficient, and this hardware was eventually supported by the old DOS games from Sierra and Id.

[FK] has a demo of this LPT DAC available here, but we’re not thinking that link will last long. If anyone has a better link, leave a note in the comments and we’ll update this post. Thanks [beavel] for sending this in.

Bring A Hack At World Maker Faire 2014

September 26, 2014 by Adam Fabio 3 Comments

After a hard Saturday at World Maker Faire, some of the best and brightest in the Hacker/Maker community descended on The Holiday Inn for “Bring A Hack”. Created by [Jeri Ellsworth] several years ago at the Bay Area Maker Faire, Bring A Hack (BAH) is an informal gathering. Sometimes a dinner, sometimes a group getting together at a local bar, BAH is has just one rule: You have to bring a hack!

[Sophi Kravitz] has become the unofficial event organizer for BAH in New York. This year she did a bit of live hacking, as she converted her Wobble Wonder headgear from wired to wireless control.

[Chris Gammell] brought his original Bench BudEE from Contextual Electronics. He showed off a few of his board customizations, including making a TSSOP part fit on the wrong footprint.

[Windell and Lenore] from Evil Mad Scientist Laboratories brought a few hacks along. They picked up an old Radio Shack music player chip at the Electronics Flea Market and built it up on a breadboard. Also on display was their new EggBot Pro. The Pro is a beautifully machined version of the eggbot. Everything is built strong to withstand the sort of duty an EggBot would see at a hackerspace or public library. [Windell] was full of surprises, as he also gave everyone chunks of Sal Ammoniac, which is a great way to bring the tin back to a tired soldering iron tip. The hack was that he found his Sal Ammoniac at a local Indian grocery in the Bay Area. Check out [Windell’s] blog entry for more information.

[Cal Howard] brought his DIY VR goggles. [Cal] converted a Kindle Fire into an Oculus Rift style head mounted display by adding a couple of magnifying lenses, some bamboo kebab sticks to hold the lenses in place. Judicious use of cardboard and duct tape completed the project. His current hurdle is getting past the Fire’s lack of an accelerometer. [Cal] planned to spend Sunday at Maker Faire adding one of his own!

As the hour grew late, everyone started to trickle out. Tired but happy from a long day at Maker Faire, the Bring A Hacker partygoers headed back to their hotels to get some sleep before World Maker Faire’s final day.

Low-Level Computing With Entry-Level Difficulty: DUO Light

September 20, 2014 by Mike Szczys 27 Comments

The hardware can’t get much simpler. The DUO Light uses an ATmega328 (commonly found on Arduino boards) along with an external SRAM chip to provide a low-level computer programming experience that will suit those new to programming and some more experienced tinkerers.

At the time of writing the modest Kickstarter goal of $1100 was just $18 shy of success. We’d wager that this is partly due to the availability of so much support material on [Jack’s] website. (fyi- a lot of the links on that page are zip files)

The SD card slot accepts a FAT16 card with byte code for the programs. The available Psuedo C compiler, and assembler let you pick your poison, or you can simply dig into the byte code directly. We didn’t see a schematic, but the firmware and BOM are both available. You should be able to easily figure out connections from those.

We’ve been a fan of [Jack’s] work for quite some time. His TTL computer and 16-core ATmega-based offerings are sure to delight, even if you remember seeing them go by the first time. This isn’t his first stab at educational models either. Though we still found his logic chip computer a bit daunting.

Stepping Through Code On A Pace 4000 Set Top Box

September 19, 2014 by Mike Szczys 14 Comments

[Lee] wrote in to tell us about a Set Top Box he hacked. Before the cable industry lawyers get out their flaming swords… he’s not stealing cable, or really doing much of anything. This is a hack just for the adventure and thrill of making someone else’s hardware design do your bidding without any kind of instructions.

He posted about the adventure in two parts. The first is finding the JTAG header and identifying the pins. Arduino to the rescue! No really, and this is the type of Arduino use we love. Using a package called JTAGenum the board becomes a quick tool for probing and identifying JTAG connections.

The image above shows a different piece of hardware. From looking at it we’re pretty sure this is a Bus Blaster which is specifically designed for JTAG debugging with ARM processors. This is the beginning of the second part of his documentation which involves code dumping and stepping through lines code (or instructions) using OpenOCD and GDB. It’s a chore to follow all that [Lee] discovered just to write his name to the display of the box. But we certainly found it interesting. The display has a convoluted addressing scheme. We assume that there are cascading shift registers driving the segments and that’s why it behaves the way it does. Take a look for yourself and let us know what you think in the comments.

Building A Vector Monitor Controller

September 18, 2014 by Brian Benchoff 19 Comments

[fredkono] has a few vintage Atari arcade boards sitting around, and without the rest of the arcade machine – especially the XY CRT – these boards would continue to gather dust. The solution to this terrible shortage of vintage video games was to build a vector monitor from scratch. No, that doesn’t mean building a new CRT, but it does mean rewiring the yoke and building a CRT controller board for tubes salvaged from small, old TVs.

Nearly all the CRTs you’ll find at your local goodwill or surplus shop are raster displays. The CRTs used in the old Atari games were vector displays and extremely similar to the tubes found in old oscilloscopes. [fred] turned the CRT found in an old 9″ color TV into a vector monitor by rewinding the yoke.

With the tube rewired, it was only a matter of connecting the custom deflection circuit boards and getting the old arcade boards running. The images drawn with the new yoke deflector board are great and produce fine, crisp lines of some of the most famous video games in history.

Build Your Own Retrocomputer With Modern Chips

September 16, 2014 by Bryan Cockfield 27 Comments

If you’ve ever wanted to get started in retrocomputing, or maybe the Commodore 64 you’ve been using since the 80s just gave up the ghost, [Rick] aka [Mindrobots] has just the thing for you: a retrocomputer based on a PIC microcontroller and a Parallax Propeller.

The two chips at the heart of the computer are both open source. The Propeller is the perfect board to take care of the I/O, video, and audio outputs because it was purpose-built to be a multitasking machine. The microcontroller is either a PIC32MX150 or a PIC32MX170 and is loaded with a BASIC interpreter, 19 I/O pins, a full-screen editor, and a number of communications protocols. In short, everything you would ever want out of a retro-style minicomputer.

The whole computer can be assembled on a PCB with all the outputs you can imagine (VGA, PS/2, etc) and, once complete, can be programmed to run any program imaginable including games. And, of course, it can act as a link to any physical devices with all of its I/O because its heart is a microcontroller.

Retrocomputing is quite an active arena for hackers, with some being made from FPGAs and other barebones computers being made on only three chips. It’s good to see another great computer in the lineup, especially one that uses open chips like the Propeller and the PIC.

Repent! The Church Of Robotron Accepts All!

September 16, 2014 by Brian Benchoff 16 Comments

Are you the mutant savior? Are you prepared for the robot uprising of 2084? Have you accepted robotron into your life? The Church of Robotron is now conducting training, testing, and confession at the new window altar in downtown Portland.

The Church of Robotron is the ~~fake~~ totally legit religion based on the classic ~~arcade game~~ prophecy Robotron 2084. In keeping with the church’s views on community outreach and missionary work, a Robotron altar has been installed at the Diode Gallery for electronic arts.

The altar consists of a system running Robotron 2084 with capacitive sensing controls built by DorkbotPDX’s own [Phillip Odom]. He’s using the same techniques featured in his capacitive sensing workshop, allowing the game to be played 24 hours a day. There are also monitors displaying the leaderboard and tenants of the Church of Robotron.

The Church of Robotron has also been showing up at Toorcamp for a few years now, with an even more spectacular altar that triggers physical events in response to game events. That’s a very cool use of MAME’s debugger, and a story worthy of its own Hackaday post.

Video of the altar below.

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