TK 90X
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The TK90X was the first Brazilian ZX Spectrum clone made in the 1980s by Microdigital Eletronica, a company located at Sao Paulo, Brazil that manufactured some ZX81 clones before (TK 82, TK 82C, TK 83 and TK 85) and a ZX80 clone (TK 80).
The case was almost the same of the original Spectrum, and the keyboard placement was equal to the original keyboard, except for some additional commands that did not exist in the Spectrums (for characters defined by the user - UDG).
There were two versions: 16 kbytes and 48 kbytes of RAM. Inside, the same processor: Z80A running at 3.5 MHz, a ROM chip, some RAM chips (old dynamic rams 4116 and 4416). Microdigital did some reverse engineering to develop a chip with the functions of the original ULA from Sinclair/Ferranti. The modulator was tuned to VHF channel 3 and the TV system was PAL-M (60 Hz).
Most of the software written for the Spectrums could be run on the TK90X, but some minor incompatibilities occurred. The cassette interface ran at a faster speed than the Spectrum. Only two peripherals were released by Microdigital — a light pen interface and a parallel printer interface.
The TK90X was replaced by the TK 95, which was almost the same circuit, but had a different keyboard and case, not in the rubber format.
Since during that period Brazilians were prohibited of importing computers, the TK90X was a large success and became the first affordable color computer of Brazilians.
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