U880

The U880 is an 8-bit microprocessor that was manufactured by VEB Mikroelektronik "Karl Marx" Erfurt in the German Democratic Republic. Production of the U880 started in 1980 at VEB Funkwerk Erfurt. The U880 is an unlicensed clone of the Zilog Z80 microprocessor, also supporting illegal opcodes and bugs, except for very minor differences like not setting the CY flag for the command.

Processor variants

The U880 was manufactured in NMOS technology and encased in a plastic DIL40 package with a pin spacing of 2.5 mm.

Temperature range	Clock rate	Designations
0 °C to +40 °C	1.0 MHz	UD880D, UB880D S1
0 °C to +70 °C	2.5 MHz	U880D, UB880D, 80-CPU
0 °C to +70 °C	4.0 MHz	UA880D, 80A-CPU
0 °C to +70 °C	8.0 MHz	U880DC08, Thesys Z80H
−25 °C to +85 °C	2.5 MHz	VB880D

The military version of the U880 has an additional "MEK 4" marking.

Support chips

VEB Mikroelektronik "Karl Marx" also manufactured a number of support chips for the U880. The prefixes UA, UB, VB, 80, and 80A correspond to the same temperature ranges and clock rates as for the processor variants above. Likewise, the suffix S1 indicates the out-of-spec, hobbyist version.

Designation	International equivalent	Description
U855D, UA855D, UB855D, UD855D, VB855D, UB855D S1, 80-PIO, 80A-PIO	Zilog Z80 PIO	parallel input/output
U8560D, UA8560D, UB8560D, VB8560D, UB8560D S1, 80-SIO/0, 80A-SIO/0	Zilog Z80 SIO/0	serial input/output
U857D, UA857D, UB857D, VB857D, UB857D S1, 80-CTC, 80A-CTC	Zilog Z80 CTC	counter/timer circuit
UA858D, UB858D, UB858D S1, 80-DMA, 80A-DMA	Zilog Z80 DMA	DMA controller
U8561D, UB8561D	Zilog Z80 SIO/1	serial input/output
UA8563D, UB8563D, VB8563D, UB8563D S1, 80-DART, 80A-DART	Zilog Z80 DART	dual asynchronous receiver/transmitter
U8272D04, U8272D08	Intel 8272	floppy-disk controller
U82530DC04, U82530DC06	Zilog SCC	serial communications controller
U82536DC04	Zilog CIO	counter/timer and parallel input/output
U82720DC02, U82720DC03, U82720DC04	Intel 82720	graphics display controller

Applications

The U880 was by far the most widely used microprocessor in the German Democratic Republic. Examples are:

office computers A 5120, PC 1715, the 1715 used a second U880 just for the keyboard.
home computers KC 85, KC compact, KC 87, Z1013, LC80 by Kombinat Mikroelektronik Erfurt
arcade game Poly Play

At the time the U880 was the most advanced 8-bit processor available in the Eastern Bloc. Only clones of the Intel 8080 were manufactured in Poland, Czechoslovakia, Hungary, Romania, and the Soviet Union. As the Z80 replaced the Intel 8080 in the West, the U880 was used throughout the Eastern Bloc. Examples are:

Poland: home computers Mera-Elzab Meritum,, Elwro 800 Junior,
Czechoslovakia: home computers Didaktik Gama, Tesla Ondra
Hungary: home computer
Romania: home computers Electromagnetica JET,,, Feper Junior
Bulgaria: office computer
Soviet Union: home computer Dubna 48K

Further development

Following the example of Zilog where the Z80 was succeeded by the 16-bit processors Z8001 / Z8002, VEB Mikroelektronik "Karl Marx" produced the U8001 / U8002. And just like its Western counterpart, the U8001 / U8002 saw far less use than the U880. When MS-DOS emerged as the dominant operating system for personal computers, in the Eastern Bloc the only available clone of the Intel 8086 was the Soviet K1810VM86. VEB Mikroelektronik "Karl Marx" then proceeded to develop a clone of the Intel 80286, the U80601. Furthermore, a CMOS version of the Z80 was developed with the designation U84C00. Due to the economic changes following the German reunification in 1990, neither project proceeded beyond pilot production. VEB Mikroelektronik "Karl Marx" was privatized in 1990 under the name ERMIC GmbH, a large part of which became Thesys Gesellschaft für Mikroelektronik mbH in 1992. Both ERMIC and Thesys continued to manufacture the NMOS version of the U880, ERMIC still with the MME name and logo, Thesys under its new name. A die shrink chip with the marking U880/6 had been developed in 1990 and went into production some time after that. The smaller chip allowed clock rates up to 8 MHz for the U880DC08 and Thesys Z80H. While Zilog likely could have taken up legal action against the successors of VEB Mikroelektronik "Karl Marx" for copyright infringement, they recruited Thesys as a Zilog distributor instead.
From about 1991 until 1993, bare U880 chips were sold to Russian and Ukrainian companies and packaged there. Initially the U880/5 chip revision was labelled as 80A-CPU and . Later integrated circuits with U880/6 chips inside received the official designation for the plastic package and KM1858VM1 for the ceramic package. Manufacturers include Angstrem Zelenograd, Kvazar Kiev, and VZPP Voronesh.