This was Brazil's first Spectrum clone.  Released in 1985 by Sao Paulo based Microdigital Electronica, the company had previously released various ZX80 and ZX81 clones. 

Microdigital Electronica made a few notable improvements over the original Spectrum. The major difference between this machine and the Spectrum was that the sound was now via the modulated RF to the TV, rather than through the beeper on the circuit board.The machine is taller with a grill on the top for better heat dispersal. Obvioulsy, the key board differed too.

At the time importing computers in to Brazil was illeagal. The TK90X became the first computer used by millions, not only in Brazil, but in several Latin American countries.