Building a Vector Monitor Controller

[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.

Homebrew Programming With Diodes


Diode matrices were one of the first methods of implementing some sort of read only memory for the very first electronic computers, and even today they can be found buried deep in the IPs of ASICs and other devices that need some form of write-once memory. For the longest time, [Rick] has wanted to build a ROM out of a few hundred diodes, and he’s finally accomplished his goal. Even better, his diode matrix circuit is actually functional: it’s a 64-byte ROM for an Atari 2600 containing an extremely simple demo program.

[Rick] connected a ton of 1N60 diodes along a grid, corresponding to the data and address lines to the 2600’s CPU. At each intersection, the data lines were either unconnected, or tied together with a diode. Pulling an address line high or low ([Rick] hasn’t posted a schematic) pulls the data line to the same voltage if a diode is connected. Repeat this eight times for each byte, and you have possibly the most primitive form of read only memory.

As for the demo [Rick] coded up with diodes? It displays a rainbow of colors with a black rectangle that can be moved across the screen with the joystick. Video below.

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The Atari Jaguar That Should Have Been


Released in 1993, the Atari Jaguar suffered from a number of problems – it was difficult to program, had hardware idiosyncrasies, and with the CD drive was vastly overpriced compared to the Sega Saturn and Sony Playstation released one year later. Nevertheless, the Jaguar still has a rabid fanbase that counts [10p6] among them, and he’s created what Atari should have released 20 years ago.

In a few forum threads at jaguarsector (login required) and (no login, German), [10p6] goes over his changes to the classic Jaguar + CD combo. He’s stuffed everything inside a new case, cutting down on the amount of plastic from the old enclosure. A proper integrated power supply has been added, replacing the two power supplies used in the original. It’s also overclocked to 32 MHz, compared to the 26 MHz of the stock unit, making this a very powerful system that could have easily competed with the Saturn and Playstation.

[10p6] has an amazing piece of hardware on his hands here, and should he ever want to make a few molds of his new Jaguar, he could put together some sort of kit to replicate this build. He’s still working on finding a model maker and perfecting his case design, but a new, improved version of the Jaguar is something we’d love to see in a limited production.

The Tiniest Video Game


As we read [Adam]’s writeup for an extremely tiny video game system through coke bottle glasses, we’re reminded of the countless times we were told that sitting, ‘too close to the Nintendo’ would ruin our eyes. We’ll happily dismiss any article from a medical journal that says there was any truth to that statement, but [Adam]’s tiny video game system will most certainly hurt your eyes.

A few years ago, Atari sold keychain-sized joysticks that contained classics such as PongBreakout, Centipede, and Asteroids. [Adam] apparently ran into a cache of these cool classic baubles and immediately thought of turning them into a stand-alone video game system.

For the display, [Adam] used a CRT module from an old Sony Handicam. These modules had the right connections – power, ground, and composite video input – to connect directly to the Atari keychain games. The result is a video game that’s even smaller than a postage stamp. The picture above shows the tiny CRT next to a 25mm postage stamp; it’s small by any measure.

How the mazes were generated for classic Berzerk game


This is a screenshot from the Atari 5200 version of the classic game Berserk. But the write-up we’re featuring actually looks at the original coin-op version. The maze for each level was established on the fly using a seed number fed into a rudimentary algorithm . Here’s a close look at how the maze building code actually worked.

Recently we saw a talk by Pitfall creator [David Crane] as part of our Retrotechtacular series. That is a real gem of programming history, and one of our favorite take-aways was that the levels were not hardcoded, but built using a random number generator algorithm with a hardcoded seed (so that the game was the same each time you played it). This uses a similar method but with a somewhat random seed.

The maze building was reverse engineered by observing the game in a MAME emulator, and by digging through disassembled code. Each time the code is “cold started” the seed starts out at zero, but from there the room number is used as the next seed. This is fed through a very simple algorithm. It generates directions for the walls, which use s few bit-wise operations to add the pillars inside the rooms.

It’s a great thing to study if you’re writing games for your embedded projects. By generating the room programmatically you don’t use up as much program memory. Of course these days even simple hobby controllers have way more storage to work with than [Alan McNeil] had when he designed Berserk.

[via Reddit]

[Image Source]

Loading Atari games from an SD card


They’re not a 2600, but the Atari 400, 800 and 1200 are awesome computers in their own right. With only BASIC built in to the ROM, they’re not especially useful or fun, as [Jeroen] found out when he acquired an 800 with a broken tape drive. There are options that allow you to load emulator files from a PC, but [Jeroen] wanted something more compact. He came up with a way to load games and apps off an SD card using a simple microcontroller.

The 400, 800, and 1200 each have a port that allows the computer to talk to printers, modems, disk drives, and load games. There are already a few circuits around that connect the SIO port to a computer so games can be loaded, but [Jeroen] wanted a more compact and portable solution for his 800.

What he came up with is actually pretty simple; just an Arduino, SD card, and an LCD display that allows him to browse the directory on the SD card and load it into the 800’s memory.

A lot of folks over on the Atariage forums are really impressed with [Jeroen]’s work, and would like to get their hands on one of these boards themselves. The project isn’t done just yet – [Jeroen] still needs to make a case for his device – but hopefully he’ll be spinning a few boards up in the coming months.

You can see a pair of videos of the device in action below.

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One game controller connects to many consoles


[Dave Nunez] wanted arcade quality controls when gaming at home. The problem was he couldn’t decide on just one console to target with his build, so he targeted them all. What you see above is a single controller that connects to many different gaming rigs.

He took a simple-is-best approach, keeping the main goal of high-quality inputs at the forefront. To start, he built the face plate out of thick MDF to ensure it wouldn’t flex or bounce as he mashed the buttons. To keep the electronics as simple as possible he soldered connections to actual controller PCBs (well, reproductions of controllers), breaking each out to a separate DB9 connector on the back of the case. These connectors interface with one of the three adapter cables seen to the right. This lets the controller work with NES, SNES, and an Atari 2600 system.

To pull the enclosure together [Dave] designed the rounded corner pieces and cut them out with a CNC mill. These connect with flat MDF to make up the sides. To give it that professional look he filled the joints with Bondo and sanded them smooth before painting.