Skip to content
Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

base register

The register in a memory operand that holds the starting address, such as rdi in [rdi + 8].

The base register supplies the starting address of an effective-address computation; every addressing mode on all three ISAs has one except x86-64's absolute and rip-based forms.

See also

addressing mode pre-indexed addressing post-indexed addressing memory operand
Read the full section →