"the first 8086 code was compiled on an 8080 (8-bit) platform and the first 8080 code was compiled on a 4040 (4-bit) platform before it."
Minor nits, the 8008 preceded the 8080. I doubt if Intel had any assembler than ran on the 4004 or 4040, they were mainly intended for "burn the EPROM, test, fix code, erase EPROMs and burn again" development cycle with the assembler hosted on something else...