Modern Microprocessors – A 90-Minute Guide (2001-2016)
> While the original Pentium, a superscalar x86, was an amazing piece of engineering, it was clear the big problem was the complex and messy x86 instruction set. Complex addressing modes and a minimal number of registers meant few instructions could be executed in parallel due to potential dependencies. For the x86 camp to compete with the RISC architectures, they needed to find a way to "get around" the x86 instruction set.I've always struggled to understand why they didn't simply retire the x86 instruction set by the early 90s.The best reason I've been given is an existing body of x86 software, but that's obviously nonsense as demonstrated by the Transmeta Crusoe and Apples's move from 68k to PPC to x86.