GMC-4 Manual from Otono no Kagaku vol 24

Based on the number visitors to my GMC-4 pages, there appears to be a fair amount of interest outside Japan in the Otono no Kagaku series, especially in the “Age of the Microcomputer” edition.  There are so many cool tech toys, tools and gadgets in Japan (Otona no Kagaku Magazine being one of them) that are rarely seen overseas.  I think the language barrier is a large part of the reason.   For this reason, I have decided to translate the GMC-4 manual pages from volume 24 of Otona no Kagaku.  I will place the original Japanese and the English translation side by side so you can use this document as a Rosetta Stone of sorts.  I will be adding to this page over time as I complete the translation of subsequent sections.  Please check back often.

To give credit where credit is due, the original manual pages in Japanese are credited to Takuya Matsubara.  The manual starts on page 46.

1 各部名称=Naming the Parts

2進LED = Binary LEDs

A line of 7 LEDs.  Displays a 7-bit binary number.

数字LED = Numeric LED

A 1 digit, 7 segment LED.  Displays a number, letter, or …

スピーカー = Speaker

Outputs key press sounds, musical notes, etc.


Central Processing Unit.  For more details, see page 48.

ハードウェアリセットスイッチ = Hardware Reset Switch

A switch to restore the power on state.  Pushing the switch (re-)initializes the memory contents.

数字キー = Numeric Keys

Keys for punching in data.  There are 16 in all.

RESET (リセット)キー = Reset Key

A key to halt a program, return the address (pointer) to 00, or …

RUN(ラン)キー = Run Key

A key to start the execution of a program.

INCR(インクリメント)キー = Increment Key

A key for reading or writing data.

A SET(アドレスセット)キー = Address Set Key

A key for setting the address.

Mini Specification:

動作クロック周波数 4 MHz Clock Frequency 4 MHz
RAM容量 プログラムメモリ80ニブル(40バイト)
RAM Size Program Memory: 80 nibbles(40 bytes)
Data Memory: 16 nibbles (8 bytes)
レジスタ数 計8個(A/B/Y/Z/A’/B’/Y’/Z’) No. of Registers 8 (A/B/Y/Z/A’/B’/Y’/Z’)
入力機能 キーボード、ハードウェアリセット Inputs Key pad. Hardware reset
出力機能 2進LED、数字LED、スピーカー Outputs Binary LEDs, Numeric LED, speaker

6 Responses to “GMC-4 Manual from Otono no Kagaku vol 24”

  1. Translation of GMC-4 Manual Pages « A walk along the denkigai Says:

    […] contained within the magazine.  I have just finished the first section and published it as a separate page.  You will also find a link to this page to your right under […]

  2. Gerald Aitken Says:

    Hello, I live in the U.S. and your Gakken GMC-4 microcomputer just arrived. I do not know Japanese but by looking at the pictures in your manual, I got most of it assembled. However I am stumped by the last step: making the actual keyboard stick to the keyboard separator. What should I do? Lick the back of it and then press it on? Kindly advise me. Thank you.

  3. Gerald Aitken Says:

    Hello, as you know I’m an American who doesn’t know Japanese who just bought the Gakken GMC-4 Microcomputer. Great machine! And I really like your blog, Denkigai! I have two questions: (1) I understand the first six built in programs, but when I run the seventh (morse code generator) I can only get the machine to display a 5. Shouldn’t I hear some morse code? Please, how do I get this program working? Second question – (2) As to the ten sample programs that are not built in, that have to be keyed in, could you please provide one-liner explanations of what each program does? If I just have that, I can figure out the rest. Thanks a million!

  4. aspro648Ken Says:

    Can you translate the text on pg. 26? I’m interested in doing the heart.

    Also, what are the program names in section 8 (pg. 58 – 78?)


    • denkigai Says:

      Hi Ken,

      I translated the program names a while ago for Gerry but never got around to posting them. The sample program names are as follow:

      Program 1: 15 Second Counter
      Program 2: Electronic Dice
      Program 3: 1 Digit Hexadecimal Addition
      Program 4: Binary LED Light Show
      Program 5: Analog Lighting of the Numeric LED
      Program 6: Largest Value Calculation
      Program 7: Random Music Player
      Program 8: Rock, Paper, Scissors
      Program 9: Sequence Music
      Program 10: Gun Fighter Game

      As for the heart program, if this is the program I am thinking of, it is a persistence of vision experiment. Once the program is running, you move the GMC-4 side to side and the flashing leds will form a shape or in this case, little hearts.

      Unfortunately, I cannot provide a complete translation as I am currently living in Honolulu and my GMC-4 is locked up in storage back in Seattle.

      The Denkiguy

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