“In modern CPUs, bugs can often be fixed through a microcode patch that updates the CPU during boot.”
Early 8086 chips could corrupt memory if an interrupt landed right after a stack segment change. Intel patched it in silicon, with gates scattered into unused corners of the die. The fix blocks interrupts after any segment register load, broader than the bug needed. Modern x86 still carries a version of that delay. Forty-four years of compatibility, visible under a microscope.