The U880 CPU was used between 1980 and 1989 in the KC 85/2, KC 85/3 and KC 85/4 computers (manufactured by VEB Mikroelektronik "Wilhelm Pieck" Mühlhausen), in the Z1013 (manufactured by Robotron Riesa), Robotron A 5120, 1715 and also in other office and amateur computers in the GDR.
The U880 is an almost identical copy of Zilog's 8-bit Z80 microprocessor. Differences include absence of CY flag setting in OUTI command (when L goes zero) and another behaviour of hidden bus register seen through undocumented F3 and F5 flags. Russian КР1858ВМ1 chips work the same way as U880.
The U880 was developed and manufactured as a non-licensed reproduction by VEB Mikroelektronik "Karl Marx" (Erfurt). A pin and function-compatible CMOS processor system with the designation of U84C00 was also under development.
The variant UB880 corresponds to the original Z80 processor, the UA880 to a Z80A CPU and the VB880 to a Z80 version with extended temperature specification (-25°C to +85°C) for industrial applications. The military version of the U880 has a additionally "MEK 4" marking. Reproductions of Zilog's peripheral components PIO (U 855), SIO (U 856), CTC (U 857), DMA (direct memory access) (U 858) and DART (U 8563) were also manufactured.