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Seems to me starting with microprogramming adds complexity that doesn't necessarily make sense for a risc instruction set? Heck, this guy does a Verilog Z-80 w
by GeorgeTirebiter 6y ago
Seems to me starting with microprogramming adds complexity that doesn't necessarily make sense for a risc instruction set? Heck, this guy does a Verilog Z-80 without microprogramming. https://dl.acm.org/doi/book/10.5555/3199987 https://dl.acm.org/doi/book/10.5555/3199987
While true the microprogramming ops are much simpler, the inherent parallelism means writing that stuff and getting it correct is usually challenging.
- musicale 6y agoI think the "microprogramming" bit can/should simply be a multi-cycle, non-pipelined implementation. Non-pipelined is easier to write and debug, especially if you are used to regular sequential programming; once you have that working then it isn't too hard to turn it into a pipelined implementation. A basic RISC style design is probably easier than a Z-80 because of the simpler addressing modes and the simpler decode.