Despite the similar name, these computers have no relation to the KC 87 series, which was made by the better-known VEB Robotron-Meßelektronik.

The KC 85/4 was the last model in the series. The first version was introduced as the KC 900 in 1984 and was renamed KC 85/2 in 1985. This was followed by the KC 85/3 in 1986 and the KC 85/4 in 1988. The final model had a clock speed of 1.77 MHz, slightly faster than its predecessors, which operated at 1.75 MHz.

The KC 85/2 was the first computer produced in Mühlhausen. It featured only a character ROM with uppercase letters and lacked a built-in BASIC interpreter in ROM. The later KC 85/3 included a KC-BASIC interpreter in ROM, freeing users from the need to load BASIC from a cassette each time.

Both systems came standard with 16 KB of usable RAM, but this could be expanded via plug-in modules. These module slots are clearly visible in photos, as they occupy the top half of the case.

The KC 85/4 had 64 KB of RAM (excluding over 40 KB of video memory) and offered improved graphics capabilities. Interestingly, the KC 85/2 and KC 85/3 were nearly identical in terms of circuit board design; the main differences were the ROM content and the presence of a built-in piezo speaker. The KC 85/4 introduced a redesigned motherboard, but still used the same digital-to-analog video PCB as its predecessors.