While trying to revive a Donkey Kong Jr arcade board, [Jelmer Bruijn] found himself in the market for an EPROM programmer and became the proud owner of a 1990’s era Dataman S4. Despite its age, it’s a fairly nice tool which allows you to read and write a laundry list of different EPROM types, all without being tied to a computer. The only catch is that a few types of chips need an adapter to work in the Dataman S4, some of which are unsurprisingly no longer available.
After some above and beyond support from the current crew at Dataman set him on the right track, [Jelmer] decided to try his hand at reverse engineering how the old adapters worked so he could build his own. His ultimate goal was to read 40 pin EPROMs on the 32 pin Dataman S4, but in the end he says the information he gathered should be applicable for building other adapters if you ever find yourself in need of such things.
As you might expect, there’s a bit more to the project than a simple pin adapter. [Jelmer] assumed some kind of shift register or latching arrangement would be required to make up for the shortage of pins on the Dataman S4’s ZIF socket. It was just a matter of figuring out how it all went together.
Luckily, [Jelmer] found that the programmer would happily attempt to perform operations on a 16 bit EPROM even though no adapter was physically present. This gave him a chance to probe around with a logic analyzer to figure out what it was trying to accomplish. The trick turned out to be splitting the 16 bit bus into two 8 bit buses which are requested sequentially.
With careful observation, close studying of 16 bit chip datasheets, and much brow furrowing, he was eventually able to come up a design that used five 74xx573 latches and put a schematic together in Eagle. There were a few kinks to iron out when the boards finally arrived, but ultimately the design worked on the first try. [Jelmer] says the same technique should work for 42 pin EPROMs, but as Dataman still actually sell adapters for those he decided not to supply schematics for it.
[Jelmer] tells us that he was inspired to send this success story our way after reading how our very own [Elliot Williams] took the long away around to erase a couple UV EPROMs recently While this isn’t the first time we’ve seen somebody have to hack support for 16 bit EPROMs into their programmer, it’s good to see that the manufacturer at least had the customer’s back in this case.
The phrase “Go big or go home” is clearly not lost on [Adam Haile] and [Dan Ternes] of Maniacal Labs. For years they’ve been thinking of creating a giant LED matrix where each “pixel” doubled as a physical push button. Now that they’ve built up experience working on other LED projects, they finally decided it was time to take the plunge and create their masterpiece: the Bixel.
Creating the Bixel (a portmanteau of button, and pixel) was no small feat. The epic build is documented in an exceptionally detailed write-up on the team’s site, in addition to the time-lapse video included after the break. [Adam] tells us the Bixel took around 100 hours of assembly, and we don’t doubt it. This is truly one of those labors of love which is unlikely to be duplicated, though all of the source files for both the hardware and software are available if you’re feeling brave enough.
The write-up contains a lot of fascinating detail about the design and construction of the Bixel, but perhaps the least surprising of all of them is that the final product ended up being very different from what they originally envisioned. The plan was to simply use lighted arcade buttons in a 16×16 grid, as they were purpose-built for exactly what the guys had in mind. But when they priced them out, the best they could do was $2 a pop. That’s $500 for just the buttons alone, before they even got into the enclosure or electronics. Like any good hackers, [Adam] and [Dan] decided to ditch the ready-made solution and come up with something of their own.
In the end, they cut the individual LEDs out of RGB strips, and soldered them down to their custom designed 500mmx500mm PCB. To the sides of each section of strip are two tactile switches, and above is a “sandwich” made of laser cut acrylic. The sheet closest to the LEDs has a 25mm hole, the top sheet has a 20mm hole, and between them is a circle of acrylic that acts as the “button”. Once it’s all screwed together, the button can’t fall out of the front or move from side to side, but it can be pushed down to contact the tactile switches.
To wire it all up they took a cue from the DIY keyboard scene and used a Teensy, some 595 shift registers, and 256 1N4148 diodes. A Raspberry Pi running their Python framework does the heavy computational lifting, leaving the Teensy to just handle talking to the hardware. Overall it’s a fantastic design to emulate if you’re looking to create large arrays of buttons on the cheap; such as whenever you get around to building that starship simulator.
Continue reading “Bixel, An Open Source 16×16 Interactive LED Array”
Sometimes you have to switch a light. Maybe it’s an LED but sometimes it’s mains-powered. That’s not too hard, a transistor and a relay should do it. If you have to switch more lights, that’s not too bad either, as long as your microcontroller has enough free GPIOs. But, if you need to switch a large number of lights, like 256 of them, for example, you’re going to need something else.
[Jan]’s project didn’t switch quite that many lights, but 157 of them is still enough of a chore to need a creative solution so he decided to use a 256-bit shift register to do the legwork. The whole thing is powered by a NodeMCU ESP8266 and was professionally built on DIN rails in a metal enclosure.
The build is interesting, both from a technical point of view and from an artistic one. It looks like it uses more than a mile of wiring, too. The source code is also available on the project page if you happen to have a need for switching a huge number of lightbulbs. Incandescent blulbs aren’t only good for art installations and lamps, though, they can also be used in interesting oscillator circuits too.
It might look like a random pile of wires to some, but it is far from random: [Paulo Constantino] built this 8-bit CPU himself from scratch. He built his remarkable creation using wires and 74HC shift register chips, plus a selection of LEDs to show the various registers.
Running at a maximum of 5MHz, it has an 8-bit data and address bus, although the latter can be expanded to 16 bits. It’s not mining Bitcoin (yet), but it can do things like play the Mario theme. His latest addition is the addition of the ability to write data out to flash memory, and he is looking to add a keyboard to make programming easier.
At the moment, he has to program the CPU by setting DIP jumpers. It’s an impressive, if somewhat frightening build that [Paulo] says took him a couple of days to design and a week or so to build. We’ve seen a few breadboard CPU builds, (some of which were tidier) and builds with similar shift register chips, but this one scores big in the blinky light and mad genius stakes.
Thanks to [AnalogMind] for the tip!
Continue reading “Home Made 8-Bit CPU Is A Wiry Blinky Build”
[Max Breedon] found an old Apple IIe clone twenty years ago. He recently dug this Epson AP-200 out of the salvage heap and quickly discovered that the keyboard decoder chip was fried. The old chip was way too obscure to source a replacement — and soon this post will be the top Google result for the string, ‘C35224E’ — so he busted out his trusty UNO and created a replacement keyboard decoder.
Unlike the Apple II, where all the keyboard decoding happens on the keyboard, this clone used a dedicated chip on the main board. Although it’s a rare part that’s virtually ungoogleable, this chip’s architecture and pinout can be figured out by testing out every trace for continuity. After locating what looked like four data pins, he had the Arduino send signals onto the clone to see what characters popped up. That didn’t work, but it led him to idea that two of the wires were clock and data, and after a bit of experimenting figured out that the third pin was a latch enable of some sort that sent the character.
So, [Max] created an Arduino rig to do the same thing. The Arduino uses a shift register to interact with the keyboard’s 8×10 matrix, and the sketch translates any serial data it receives into the keypresses the clone is expecting. After prototyping with the UNO, [Max] hardwired an Arduino Nano (as well as the shift register) into a daughter board with pins extending into the old chip’s sockets. A permanent solution!
In addition to a weird keyboard controller that has been lost to the sands of time, this Apple IIe clone features a few more parts that are downright weird. There are two chips that are found in a few other Apple clones labeled STK 65301 and STK 65371, used as ASICs, MMUs, or a 20-IC expression of Wozzian brilliance condensed into custom silicon. There’s another weird chip in this clone, a 27c32 ROM loaded up with repetitive bits. There is no obvious 6502 code or strings in this ROM, so if anyone has an idea what this chip does, send [Max] a note.
[visualkev]’s friend was putting on his own fireworks show by lighting each one in turn, then running away. It occurred to [visualkev] that his friend wasn’t really enjoying the show himself because he was ducking for cover instead of watching the fun. Plus, it was kind of dangerous. Accordingly, he applied his hacker skills to the challenge by creating a custom fireworks sequencer.
He used a custom PCB from OSH Park with an ATMega328P controlling eight TPIC6C595 8-bit shift registers, which in turn trip the 64 relays connecting to the fireworks. A 5V regulator supplies the project from 5 5AA batteries, and he kept the wires neat with 8-wire ribbon cables.
Starting the sequence is a generic wireless remote — a cheapie from Walmart — allowing [visualkev]’s friend can launch the fireworks with one hand while working the barbecue tongs with the other.
DEF CON 25’s theme was retro-tech, and [xres0nance] wasn’t kidding around in the retro badge he built for the convention. The badge was mostly built out of actual parts from the ’80s and ’90s, including the perfboard from Radio Shack—even the wire and solder. Of the whole project just the resistors and 555 were modern parts, and that’s only because [xres0nance] ran out of time.
[xres0nance] delayed working on the badge until his flight, throwing the parts in a box, and staggering to the airport in the midst of a “three-alarm hangover”. He designed the badge on the plane, downloading datasheets over in-flight WiFi and sketching out circuits in his notebook.
The display is from an old cell phone, and it uses a matrix of diodes to spell out DEFCON without the help of a microcontroller. Each letter is powered by a transistor, with specific pins blocked out to selectively power the segments. He used a shift register timed by a 555 to trigger each letter in turn, with the display scrolling the resulting message.
We publish a lot of posts about con badges. See our DEF CON 2015 badge summary for a bunch of badges that we encountered at in Vegas.