10 ms·

John Mashey on RISC/CISC

• Scaevolus 11y ago
  For context, here's the thread from 1991: https://groups.google.com/d/msg/comp.arch/rYgGszm_dGk/z7p0orP7r0IJ https://groups.google.com/d/msg/comp.arch/rYgGszm_dGk/z7p0or... One interesting comment: Hey, you left out the Acorn Risc Machine. Not a big name in the workstation market, but I understand that they sell a good number of them, and the instruction set is "interesting" (a bit-twiddler/ superoptimizer's wet dream, if you ask me, but probably "risc" by many definitions of the term). VTI sells this chip in the US, they should be able to give you a spec if you want it. I wonder what a modern table would look like. There's been a fair amount of turnover in RISC, now largely dominated by ARM, with MIPS and PowerPC also contenders, and CISC is still dominated by x86.
  • kps 11y ago
    > and the instruction set is "interesting" (a bit-twiddler/ > superoptimizer's wet dream, if you ask me All fallen by the wayside in Thumb and ARM64, now. > but probably "risc" by many definitions of the term What ARM lacked in academic purity it made up in pragmatic simplicity of implementation. You could look at the instruction set and practically see the gates.
    • renox 11y ago
      > What ARM lacked in academic purity it made up in pragmatic simplicity of implementation 'pragmatic simplicity of implementation'? Mmm, what about LDM/STM (load/store multiple registers)? Of course they dropped this with the ARMv8 (64bit) ISA.. I wonder if they are still interesting differences between the ARMv8 and the MIPS ISA? From my (uninformed) POV they look very similar..
• hga 11y ago
  Interesting how history seems to have ratified the more RISCy of the CISC designs, IBM 360 and Intel x86 are survivors, the Motorola 68000 and DEC VAX died hard deaths, especially the VAX, which didn't lack support from DEC.