Modern x86 CPUs still boot as a 1978 Intel 8086, and Intel gave up removing it

Intel and AMD processors still start in the 16-bit "real mode" of the original 1978 Intel 8086, with 16-bit registers and no memory protection or paging. Intel acknowledges its Intel 64 chips come out of reset in the same state as the 8086, and abandoned its X86S proposal to drop this legacy in 2024.

• The first CPU instruction runs in 16-bit Intel 8086 mode from 1978
• Intel: Intel 64 designs come out of reset in the same state as the 8086
• In a QEMU UEFI test, only 18 instructions ran in real mode before 32-bit
• Intel abandoned its X86S proposal to remove real mode in 2024