Microdigital TK85

This is a unlicensed ZX81 clone with 16K or 48K of memory. The rear has a blanked out socket space labeled “SOM” (sound) next to the 9V socket, although the machine doesn’t have any sound capabilities.

Besides the standard 8Kb ROM, the machine has an additional 2Kb EPROM with some useful ROM routines:
RAND USR 8630 is a high speed loader (14 times faster than LOAD “”);
RAND USR 8405 is a high speed save routine; RAND USR 8539 is a high speed verify routine;
RAND USR 8192 creates a REM line consisting of dots to store machine code in (POKE 16514 and 16515 with the number of dots)

The joystick port (6-pin DIN 45322) is cursor-key compatible (56780).