After the TK80, TK82 and TK83 the TK85 was the last ZX-81 compatible machine Microdigital produced.
However it wasn't only a simple copy of the ZX-81 but featured several useful enhancements. Its rubber keyboard and case were similar to the Spectrum's and were much more pactical for intensive use. The 10 KB ROM held an improved version of the Sinclair's Basic with strings management and editing facility, as well as some primitive graphic commands.
Several additional routines allowed to record tape programs up to 4200 bits per second, manage a joystick interface and the built-in three-voice sound generator.
Thanks to the TK85, Microdigital started to lead the Brazilian home computer market, front of Sinclair and its US branch, Timex.
Thanks to Joao Roberto for most of the pictures and information.