David, thank you for response.

Yes, I understand developement cycle in its simple form - editing and assembling in PC, then loading binary file into flash (or whatever else memory) on chip or on board.
I was just curious about the assembler in 8052 SBC, becuse I've never seen something like this before - I saw various interpreters (like BASIC or Forth), various monitor programs, but on-chip assembler is really something uncommon - at least for me.