NEC also made a chip, I think it was called the N300 that executed Z80 instructions but was clock and buss compatible with the 8088. This allowed a machine to have both Z80 and 8088 compatible CPUs on the same board. My Octagon 8/16 S100 machine had this and could boot CP/M-80, CP/M-86 Concurrent CP/M-86 and MS-DOS.