Z80A

The Z80A is a variant of the Zilog Z80 microprocessor. It was introduced to provide higher performance while preserving full software compatibility with the Z80 instruction set. The “A” suffix indicates an enhanced version targeted at higher clock speeds; the core architecture and programming model remain the same.

Like the original Z80, the Z80A is an 8-bit processor with a 16-bit address bus supporting up to 64 KB of memory. It uses registers A and F, and the BC, DE, HL register pairs, plus alternate registers, and 16-bit SP and PC. It also includes the IX and IY index registers.

Clock rates for the Z80A were typically up to 4 MHz, roughly doubling the throughput of the original Z80, although exact speeds varied by package and system designer. The Z80A remained instruction-compatible with the Z80, enabling existing software to run with minimal modification.

During the early to mid-1980s, the Z80A and related Z80 variants were widely used in 8-bit microcomputers, embedded systems, and embedded controllers. The Z80 family influenced the design of later processors and remained in use in some applications for many years.