The newest Gakken kit is a 4-bit computer, and there is  a programing guide for this here. Will try to find some audio, but looks it might be good for fans of beeper music.

The GMC4 has a 16-key keyboard, a build-in speaker, a 7-segment LED display, and a 6 LED display. A tennis game, music software, and two other 4-bit games come pre-installed in the GMC-4.

While drinking some great Kirin beer with friends from Sansai Books and Gizmodo Japan, I listened to the introduction speech by the Gakken editors. The inspiration for the GMC-4 comes from the TK-80, released by NEC in 1976, and partially, from the FX MYCON R-165, which Gakken released in 1983.

Several people in the room had the GMC-4 with them, so the speaker started to read some code and help everyone with a GMC-4 to program it “live.” Then they introduced the Arduino, and being Italian, I was really happy to see how a board “Made in Italy” is so well received by Japanese engineers and toy hackers!

With the presentation finished, it was time for my friends Polymoog and Gan to play live with a special setup of three GMC-4s patched into Gakken SX150 analog synths. Gan is the guy who designed the SX150, and once in a year, with Abe, he organizes the Analog Synthesizer Builders’ Summit Party in Tokyo.

via Make: Online : Gakken mag and 4-bit computer rollout party in Tokyo.