The TK90X

1985 · Brazilian Spectrum Clone · Work 993 of 1,871

A narrow desk by an open window in a high-rise flat in São Paulo at dusk on a hot summer evening, a flat home computer twenty-four centimetres wide in matt black plastic, across its upper third a field of slanted ventilation ribs, four rows of small grey-blue keys, every key plain smooth and unmarked, above the top row a thin strip of small plain colour fields in blue, red, magenta, green, cyan, yellow and white, two hands in yellow short sleeves typing, a small television in a wood-grain cabinet glowing soft even blue, a flat cassette recorder, a glass of orange juice, pink haze over tower blocks beyond.

What it was used for
Brazilian copy of the ZX Spectrum 48K, launched in June 1985 by Microdigital Eletrônica Ltda. of São Paulo, a firm founded in 1981 by the brothers George and Tomas Roberto Kovari, which had already copied the ZX80 and ZX81. Z80A at 3.58 MHz, 16 or 48 KB RAM, 16 KB ROM, a 40-key rubber keyboard, an expansion slot and connections for cassette recorder, joystick and television; sound went through the TV signal rather than a beeper on the board. Computer imports were not permitted at the time, and so, in the Centre for Computing History's account, the machine became the first computer for millions of people in Brazil and Latin America.
What was new
What was new was not the circuit but its recovery: Sinclair made the Spectrum's ULA chip for itself and did not sell it to other firms, so Microdigital reverse-engineered it (Museu Capixaba). Added to that were a modified ROM with Portuguese and Spanish characters, an extra command for user-defined graphics and a switchable TV standard: PAL-M at 60 Hz, PAL-N at 50 Hz or NTSC. The barb sits in that same ROM. Microdigital promised full compatibility; the Centre for Computing History puts it at about 90 to 95 percent, and the Museu Capixaba records that part of the British software library did not run.

What the sources leave open: No source checked gives sales figures; the Museu Capixaba says only that the machine sold well in Brazil and South America. Prices are not attested: the page refers to 2 advertisements with different launch prices without naming amounts. Whether any Sinclair licence existed is stated expressly by none of the sources.

Further reading