&gt; <i>A contemporary x86, RISC, mixed (ISA + accelerators), or what other CPU? I think CPU is a broad term. :) Anyway, Wikipedia has a detailed write-up that assembly experts can base a comparison on:</i><p>Contemporary x86 and RISC CPUs are what I was comparing the PDP-11 instruction set to. I don&#x27;t see any fundamental differences. Painting with very broad strokes, the PDP11 ISA looks reasonably close to x86. And those minor differences in more modern RISC actually map <i>better</i> to C than the PDP 11 does -- for example, status flags being replaced with jumping based on register contents. Implicit widening to words is a weak mismatch for x86, but it&#x27;s a pretty good match for modern risc (no need to mask out top bits in registers), etc.<p>I looked at your links, and I&#x27;m still not seeing how other C maps better to a PDP-11 than it does to modern CPUs. The only thing I&#x27;m seeing in the pastebin rant is that CPUs are fast enough and memories are big enough today to support more expensive features, which I can agree with.<p>Again:<p>&gt; <i>Worked fine for a PDP-11. Yet, forcing its memory model or tradeoffs into a language used on different hardware can cause unnecessary problems.</i><p>What parts of its memory model or tradeoffs made it into C? I can&#x27;t find any specifics that you&#x27;re basing these claims on, only assertions that it&#x27;s true.<p>In fact, the usual complaint associated with C is that it left the memory model so loosely specified -- initially to allow it to match any hardware -- that optimizing compilers can use the looseness to do really strange things to your code.