Demystifying NTSC Color And Progressive Scan

NTSC

Black and white NTSC is simple – it can, and was, done with vacuum tubes for a long, long time. Color is just weird, though. It runs at 29.976 frames per second, uses different phases of the carrier for different colors, and generally takes a while to wrap your head around. [Sagar] is doing a series on the intricacies of NTSC, and the latest post deals with color and progressive scanning versus interlacing, or as it is better known, how classic game consoles and home computers generate video.

The test bed for [Sagar]‘s video experimentations is a circuit containing an ATMega16, a 4-bit shift register, and a 14.31818 MHz clock. This clock is much faster than the 3.579545 MHz clock in an NTSC carrier frequency – exactly four times as fast – allowing the shift register to output four different phases of the carrier frequency a 0°, 90°. 180°, and 270°. Playing with some of the pins on the ATMega in the circuit results in a palette being generated on any old TV.

NTSC requires interlaced scanning, or sending an entire screen of even lines, then an entire screen of odd lines, at around 60 fields per second. The Nintendos and Segas of yesteryear didn’t bother with this, instead opting to send half the vertical resolution at double the frame rate. This is known as a progressive scan. [Sagar] found that this resulted in some image artifacts when displayed on a modern LCD, and moving back to an interlaced mode fixed the problem. All the code and files are up on the gits. If you’re feeling adventurous, this is exactly how projects like the Uzebox have created homebrew game consoles using little more than the ATMega found in [Sagar]‘s build.

BigBoy Advance, a Giant GBA for Big Hands

big boy advance

Ever wish Game Boys came in a slightly larger size? [John], aka [Bacteria] of Bacman, decided to try something different with this retro console mod — the BigBoy.

In case you’re not familiar with the Bacman website, it’s a site dedicated to retro video game console modding — and our hacker, [John] is the man behind the scenes. We’ve shared plenty of their projects before.

The BigBoy is basically a Game Boy Advance — with an 8″ display. It uses the electronics from a knockoff copy of a RetroBit in a custom case that [John] vacuum formed at home. He sketched out the proposed outline, built a mold out of plastic sheets and hot glue, and created a concrete dummy mold for the vacuum former — meaning if he ever wanted to recreate this project it would be a piece of cake!

[Read more...]

Commodore 64 and Nintendo Make Beautiful Music Together with SYNCART

Cyncart

[Dan] has been hard at work developing CYNCART to get his Commodore 64 and original NES to play together. We’ve seen [Dan's] handiwork before, and it’s pretty clear that he is serious about his chip tunes.

This project starts with something called a Cynthcart. The Cynthcart is a Commodore 64 cartridge that allows you to control the computer’s SID chip directly. In effect, it turns your Commodore 64 into a synthesizer. [Dan] realized that the Commodore’s user port sends out simple eight bit values, which happens to match perfectly with the NES’ controller ports. In theory, he should be able to get these two systems communicating with each other.

[Dan] first modified the Cynthcart to send data out of the user port on the Commodore. This data gets sent directly to the NES’ 4021 shift register chip in the second player controller port. The NES runs a program to turn this data into sound on the NES’ audio chip. The first player controller can then be used to modify some other sound settings on the NES. Musical notes are played on the Commodore’s keyboard. This setup can also be used to play music on both systems at the same time. Be sure to watch the video of the system in action below.

[Read more...]

Original NES Guts Upgraded with RetroPie

NES RetroPi

If you have an old broken NES lying around and have no idea what to do with it, you may want to check out [snoius's] latest project. He replaced the guts of his old NES with a Raspberry Pi. [snoius] started out by removing most of the electronics from his original NES to make room for the Pi. He left the original control panel board so he would be able to use the original power button and power LED. The NES power switch is an on/off toggle switch. [snoius] decided to just route the 5V USB power input directly through this switch. The result is a hard power switch for the tiny computer. The original power LED is wired up to the Pi’s 3.3V GPIO header through a 330 ohm resistor. Now when the Pi has power, the LED lights up.

The next step was controllers. It looks like [snoius] is using some USB SNES controller clones. He wanted to use the original NES controller ports but obviously the NES did not utilize USB. [snoius] used a saw to cut the backs off of the controller ports, leaving a flat surface. He then used a utility knife to carve out a hole in the shape of a female USB port. He mounted some ports in place and then wired the inside up to some short USB cables with male ends. These were plugged into a USB hub that is hidden inside of the NES case.

The Pi is also hooked up to a short HDMI cable and a short power cable. The loose ends of the cables are mounted to a small block of wood. Notches are cut out of the wood to better fit the cable ends. The rear of the NES has two holes cut out where the original connectors used to be in order to accommodate the new connectors.

With all of the hardware taken care of, [snoius] still needed a way to actually play his games. That’s where RetroPie saved the day. RetroPie is a Linux distribution for the Raspberry Pi that is specifically created to make it easy to play old video games. It includes emulators for many old systems including NES, SNES, SEGA Genesis, Gameboy, etc. [snoius] installed RetroPie onto an 8GB SD card and copied over all of the ROMs he could find. The end result is what appears to be an original NES at a glance, but is in fact multiple retro gaming systems in one. It also contains hundreds of video games in on board memory instead of requiring a large library of physical cartridges.

[via Reddit]

Dual Port RAM Teaches an Old NES New Tricks

nesDPR

[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.

[Read more...]

NES Cartridge Hack Makes Great Novelty Gift

NES cartridge with arduino

Most all of us recall the Blinking Screen of Death on original NES systems. This was caused by a bad connection between the cartridge and the NES cartridge connector. For whatever reason, it became a very popular idea to give a quick blow down the cartridge, even though this didn’t really help. [Dale] decided to play on this annoying problem by making the NES Blow Cart!

Inspired by a previous cartridge hack, [Dale] mounted a custom made circuit sporting the ever popular ATtiny85 in a Super Mario / Duck Hunt cartridge. A small microphone sits where the original cartridge connector was, along with the on/off switch and program header. A quick blow triggers the ATtiny85 to play a song.

The most difficult part for [Dale] was to figure out how to get the ATtiny to play “music”. This was solved with the discovery of a library called Rtttl. This allowed him to take old Nokia Super Mario and Zelda ringtones and get them on the Attiny85. All files, including the rtttl library are available on his github. Be sure to stick around after the break for a video of the project in action.

[Read more...]

The 8 Bit Harmonica Blows In From Japan

8bit-harmonica

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.

[Read more...]

Follow

Get every new post delivered to your Inbox.

Join 96,545 other followers