KR1858VM1 - soviet Z80 : weekend die-shot

KR1858VM1 - Z80-compatible CPU, manufactured in USSR. Die marking "U880/6" suggests that it was also designed in east Germany company VEB Mikroelektronik "Karl Marx" in Erfurt (MME). Compared to T34VM1 die size is shrunk by a factor of 1.6, reworked IO.

Also, you can compare it to MME Z80A and Zilog Z80.

Die size 3601x3409 µm.