| ▲ | jcranmer an hour ago | |
One of my biggest bugbears in CS instruction is the overdue emphasis on RISC v CISC, especially as there aren't any really good models to show you what the differences are, given the winnowing of ISAs. In John Mashey's infamous posts [1] sort of delineating an ordered list from most RISCy to most CISCy, the architectures that are the most successful have been the ones that really crowded the RISC/CISC line--ARM and x86. It also doesn't help that, since x86 is the main goto example for CISC, people end up not having a strong grasp on what features of x86 make it actually CISC. A lot of people go straight to its prefix encoding structure or its ModR/M encoding structure, but honestly, the latter is pretty much just a "compressed encoding" of RISC-like semantics, and the former is far less insane than most people give it credit for. But x86 does have a few weird, decidedly-CISC instruction semantics in it--these are the string instructions like REP MOVSB. Honestly, take out about a dozen instructions, and you could make a solid argument that modern x86 is a RISC architecture! | ||