[Andrew] is developing a game for the Nintendo Entertainment System (NES). Emulators are great for this, but [Andy] loves running on the real iron. To help, he’s created a dual port RAM interface for his NES. As the name implies, a dual port RAM is a memory with two separate data and address buses. The Cypress Semiconductor CY7C136 [Andy] used also includes arbitration logic to ensure that both ports don’t attempt to access the same memory cell and cause data corruption. In [Andy’s] case the NES was on one side, oblivious to the new hardware. On the other side of the dual port RAM, [Andy] installed an ATmega164 running his own custom firmware.
The new hardware gives [Andy] a live view of what’s going on in the NES’s memory. He added a live memory view/edit screen similar to the FCEUX emulator. The window runs on a PC while the game itself is running on an NES. [Andy] was even able to add rudimentary break and step features by connecting his circuit to the Non Maskable Interrupt (NMI) line of the NES. By holding the NMI asserted, the ATmega can essentially freeze the game in progress.
[Andy] has even used his circuit to teach the NES some new tricks. By reading the timer and score memory locations on Ice Hockey, he was able to create a scoreboard and goal light. Similar techniques were used to give Contra a muzzle flash light which puts Ambilight systems to shame.
We don’t know what [Andy] is planning next, but we hope it’s a source release so we can start hacking some some games ourselves!
Click past the break to see a couple of [Andy’s] Vine videos.
Continue reading “Dual Port RAM Teaches an Old NES New Tricks”
From [Basami Sentaku] in Japan comes this 8bit harmonica. [Basami] must remember those golden days of playing Famicom (or Nintendo Entertainment System for non-Japanese players). As the systems aged, the contacts would spread. In the case of the NES, this would often mean the infamous blinking red power light. The solution for millions of players was simple. Take the cartridge out, blow on it, say a few incantations, and try again. In retrospect, blowing on the cartridges probably did more harm than good, but it seemed like a good idea at the time. We’d always assumed that the Famicom, being a top loading design, was immune from the issues that plagued the horizontal slot on the NES. Either [Basami] spent some time overseas, or he too took to tooting his own cartridge.
Blowing into cartridges has inspired a few crafty souls to stuff real harmonicas into cartridge cases. [Basami] took a more electronic route. A row of 8 microphones picks up the players breath sound. Each microphone is used to trigger a specific note. The katakana in the video shows the traditional Solfège musical scale: do, re, mi, fa, so, la ti, do. A microcontroller monitors the signal from each microphone and determines which one is being triggered. The actual sound is created by a Yamaha YMZ294. The ‘294 is an 18 pin variant of the venerable General Instrument AY-3-8910, a chip long associated with video game music and sound effects. While we’re not convinced that the rendition of Super Mario Bros’ water theme played in the video wasn’t pre-recorded, we are reasonably sure that the hardware is capable of doing everything the video shows.
Continue reading “The 8 Bit Harmonica Blows In From Japan”
Back in 1989, Nintendo released Tetris for the NES. This detailed article first explains the mechanics of how Tetris works, then builds an AI to play the game.
To understand the mechanics of the game, the ROM source was explored. Since the NES was based of the MOS 6502 microprocessor, this involves looking at the 6502 assembly. The article details how the blocks (called Tetriminos) are created and how they move across the screen. The linear feedback shift register used for random number generation is examined. Even details of the legal screen and demo mode are explained.
After the tour through how Tetris works, an algorithm for the AI is presented. This AI is implemented in Lua inside of the FCEUX NES/Famicom emulator. It works by evaluating all of the possible places to put each new Tetrimino, and choosing the best based on a number of criteria. The weighting for each criterion was determined by using a particle swarm optimization.
The source for both the Lua version and a Java version of the code is available with the article. Everything you need to run the AI is available for free, except the Tetris ROM. If you’re interested in how 8 bit games were built, this dissection is a great read.
[Dave] tipped us about the latest project he just finished: a posable, desktop NES clone arcade machine. This idea came to be when its creator gathered a few bits and pieces he had lying around: an NES Retro Entertainment System (Retrobit RES, found for less than $25) and an arcade stick with its buttons. [Dave] then bought a 7″ car DVD screen (less than $40) and started a first standard arcade-looking design with OpenSCAD. As the first draft was relatively boring, he let it mature for a bit until he got another idea, shown in the picture above.
The final result is made of 3D printed PLA and varnished luaun plywood which gives the console a VCS style retro look. Many hours were required to 3D print the different parts using a Makerbot Replicator 2. [Dave] disassembled his Retrobit RES to layout its parts inside the case and also replaced the original voltage regulator with a 7805 on a big heatsink. This may be one of the best ‘nintendo’ hacks we have received over the years, but there have been others that also take cartridges.
[Quinn Dunki]’s awesome 6502-based computer is coming right along, and she decided it’s time to add one of the most important features found in the 80s microcomputers she’s inspired by – gamepads.
There were two ways of implementing gamepads back in the 80s. The Apple II analog joysticks used a potentiometer for each joystick axis along with a 556 timer chip to convert the resistance of a pot into a digital value. Analog controls are awesome, but a lot of hardware is required. The other option is the Atari/Commodore joystick that uses buttons for each direction. Surprisingly, these joysticks are inordinately expensive on the vintage market but a similar hardware setup – NES gamepads – are common, dirt cheap, and extremely well documented.
[Quinn] wrote a few bits of 6502 assembly to read these Nintendo controllers with Veronica’s 6522 VIA with the help of an ATMega168, and then everything went to crap.
In testing her setup, she found that sometimes the data line from the controller would be out of sync with the clock line. For four months, [Quinn] struggled with this problem and came up with one of two possible problems: either her circuit was bad, or the 6522 chip in Veronica was bad. You can guess which option is correct, but you’ll probably be wrong.
The problem turned out to be the 6522. It turns out this chip has a bug when it’s used with an external clock. In 40 years of production this hasn’t been fixed, but luckily 6502 wizard [Garth Wilson] has a solution for this problem: just add a flip-flop and everything’s kosher. If only this bug were mentioned in the current datasheets…
Now Veronica has two NES controller inputs and the requisite circuitry to make everything work. Video evidence below.
Continue reading “Veronica Gets A Pair Of Gamepads And A Bugged Chip”
[Petri] wrote in to show off the 8-bit gaming system and original platformer which he and [Antti] developed. Don’t get us wrong now, it’s impressive that the duo were able to put together what looks like a very interesting game. But we’ve seen many industry-leading video games developed with just one or two people (we’re thinking all the way back to the days of Atari). Nope, what’s most interesting to us is that the console is also their creation. We should note that the title screen was the work of their friend [Juho].
Take this with a grain of salt, as the bottom right image in the vignette obviously includes an Arduino. But isn’t it a testament to the state of open hardware and the sharing of knowledge through the Internet that this is even possible on the hobby level? And just because we call it “hobby” doesn’t mean you have to lower your expectations. This thing is full featured. Watch the clip after the break to see the ATmega328 driving a 104×80 resolution screen with a 256 color palette, while using four audio channels for the chiptunes. The thing even utilizes an original NES controller port for user input.
And for those of you who are thinking we’ve seen the same thing before, we never get tired of seeing projects where a lot of hard work has obviously paid off!
Continue reading “8-Bit Video Game is Best of Retro Gaming on a Shoestring Budget”
Like all good hackers [Osgeld] makes regular appearances at the thrift store to scavenge for raw materials. This summer he was lucky enough to come across a couple of NES clone games. These are controllers that emulate the original Nintendo Entertainment System by connecting to a television using composite video. The mechanics of the controllers were pretty much shot, but he knew he could do something with the boards inside. It was a small gamble at a dollar apiece anyway.
As you can see above, he upgraded a vintage NES Advantage controller by stuffing it full of the emulator hardware. To start he disassembled the arcade-like peripheral and gave everything a thorough cleaning. Since he was going to be soldering onto the PCBs anyway he upgraded the controller by swapping out the original switches for a different set of tactile switches. The large base provided plenty of room for [Osgeld] to fit the emulator (with included ROMs) and now he’s Playing with Power.
The NES Advantage is a very nostalgic controller. Even the Ghostbusters hacked on it!