Zero page - Definition and Overview

Zero page is the memory address at the beginning of a computer's address space.

In early computers, including PDP-8, the zero page had a special fast mode of addressing, which facilitated its use for temporary storage of data and compensated for the relative shortage of CPU registers. The PDP-8 had only one register, so zero page addressing was essential.

Zero page addressing has mostly historical significance, since integrated circuit technologies made adding more registers to a CPU less expensive. Some computer architectures still reserve the beginning of address space for other purposes, though; for instance, the Intel x86 systems reserve the first 256 words of address space for the interrupt table.