TADEO CZERWENY "CZ" is a an electromechanical company, which was founded by Tadeo Czerweny in September 1958. It is located in Parana, Entre Rios province, in Argentina. The company made transformers, electric motors, etc. In the 80´s Czerweny marketed the Timex Sinclair´s models, under its own name.
The CZ-1000 Plus used a brand new case, as opposed to the CZ-1000, 1500 and 2000 which used original Timex-Sinclair ones. But inside, it was just a Sinclair ZX-81 with 2 KB RAM, with a new plastic case and a chicklet keyboard.
At least two versions have been produced. The grey-key version used a dozen of standard 74xx chips. The black-key version featured a new card, redesigned by Czerweny, with only four ZX-81 chips. It also held one DIN joystick plug.
In Argentina Czerweny models competed with Brazilians TK 83, 85, 90x and genuine Sinclair machines, but CZ sold more machines than them.