> most of which are patched in microcode Because most of it is software anyway. Unless the CPU is something ridiculously simple, like an 8-bit microcontroler,

> most of which are patched in microcode Because most of it is software anyway. Unless the CPU is something ridiculously simple, like an 8-bit microcontroler, a lot of the instructions are executed by microcode stored in ROM on the CPU. What those patches do is load a replacement software in RAM at boot time.