 Unlike contemporary processors that often used a microcoded architecture (such as the 68000 and partly the 8086), the 6809's internal design was more similar to early simple CPU designs (and to some degree also the RISC machines that appeared in the mid 1970s and onwards).Like most 8-bit microprocessors, the 6809 implementation can in be viewed as a register-transfer level (RTL) machine, using a central PLA (less combinational logic) to implement much of the instruction decoding as well as parts of the sequencing.Just like the 6800 and 6502, the 6809 uses a two-phase clock to gate the latches.