Anon (no.delete@this.spam.com) on June 2, 2022 2:49 pm wrote:
> Heikki Kultala (heikk.i.kultal.a.delete@this.gmail.com) on June 2, 2022 12:04 pm wrote:
> > Everything is about tradeoffs. Before 1980's, what mattered was code size. But
> > then, in 1980's simpler decoding allowed pipelining, and the RISCs hype came.
>
> Reviewing RISC history I don't think it was simpler decoding that made RISC partical
> in the 80's, but rather simpler design which allowed CPUs to hit market earlier,
> we would be using 68k derivatives had it hit the market one year earlier.
>
> With 80's tech the optimal ISA for those in-order pipelined scalar cores would likely be more
> expressive than RISC because the expressiveness would allow the resources to be used more
> efficiently but far simpler than x86 which wasn't designed with pipeling in mind at all.


I think the simpler decoding was a far bigger deal in the late 80s / early 90s for the advantage of RISC because your transistor budget was so much smaller. When you had only a few hundred thousand transistors to play with, every one counts in a way that just isn't the case today with tens of billions at your disposal.