The MZ-80K

1978 · All-in-One Cassette Computer · Work 972 of 1,871

A student dormitory room in Kyoto on a winter night, on a grey steel desk a compact computer forty-one centimetres wide, on its flat pale grey base at the left a boxy screen housing with a bright red hood, the screen glowing soft even greenish-white, at the right a built-in cassette deck with its clear lid open above six black piano keys, a hand in a navy wool sleeve pressing a plain white cassette into the deck, at the front a narrow recessed keyboard of small square dark grey keys, yellow keys and blue keys, every key plain, smooth and unmarked, a kettle steaming on a glowing kerosene heater.

What it was used for
A machine with everything in one box: according to the Computer Museum of the Information Processing Society of Japan, the MZ-80K had a 10-inch screen showing 40 by 25 characters and 80 by 50 semi-graphic dots, a keyboard of square switches, a built-in cassette deck and a Z80. Sharp released it in December 1978 as a semi-kit; the Tama Art University collection and AKIBA PC Hotline both give 198,000 yen. The cassette deck ran at 2,100 bits per second according to AKIBA PC Hotline.
What was new
What stands out is the clean computer principle. Unlike machines with BASIC fixed in ROM, the MZ-80K held its interpreter not in ROM but loaded it from cassette tape into working memory. That allowed other languages and operating systems to be booted and removed the tie to a single language. The price: every power-up begins by reading the language off a tape running, according to AKIBA PC Hotline, at 2,100 bits per second.

What the sources leave open: The sources give different memory figures: the IPSJ museum states 20 KB of RAM, while the December 1978 dealer advertisement reproduced by AKIBA PC Hotline gives 24 KB as standard. Neither says whether both count the same thing, so the figure is left out of the text. None of the three sources gives units sold, nor who first built this way.

Further reading