[1][2] Different versions of this CPU were manufactured beginning in the late 1970s, the earliest known use being in the SM1800 computer in 1979.
While the Soviet clone appears to be fully software-compatible with Intel 8080A, there is a slight difference between the two processors' interrupt handling logic, which looks like an error in the KR580VM80A's microcode.
[8] If a CALL instruction opcode is supplied during INTA cycle and the INT input remains asserted, the KR580VM80A does not clear its internal Interrupt Enable flag, despite the INTE output going inactive.
In a typical hardware configuration this phenomenon is masked by the behavior of 8259A interrupt controller, which deasserts INT during INTA cycle.
[9] The 580VM80 is still shown on the price list of 15 August 2022 of the "Kvazar" plant in Kyiv[10] together with various support chips of the K580 series.
It adds two registers, H1 and L1, that can be used instead of H and L. Several 16-bit arithmetic instructions were added as well (DAD, DSUB, DCOMP).