The Z80 microprocessor is an 8-bit [[CPU]] with a 4-bit ALU and a 16-bit address bus capable of direct access to 64KB of memory space. The Z80 is a little-endian CPU, meaning it stores 16-bit values with the least significant byte first, followed by the most significant byte.
It has a language The Z80 instruction set is really 3 separate subsets each occupying 256 opcode ‘slots’. The main and CB subsets each occupy the full range of 252 root 256 instructions and with , while the reserved 4 bytes as ED subset is mostly empty and only implements 59 instructions. DD and FD instruction prefixes, access to an additional 308 are not counted as they are just modifiers. This means there are 571 unique instructionsin the Z80 instruction set. [https://floooh.github.io/2021/12/06/z80-instruction-timing. html Source] Although it lacks the raw processing power of processors like the Intel 80x86 or the [[Motorola 68000]] series, the Z80 is extremely useful for low cost control applications.
The Z80 has about 8500 transistors. To put it into perspective, 64KB of DRAM contains 524288 transistors, as 1 bit of DRAM needs 1 transistor. Fun fact: an Amstrad CPC equipped with a 4MB RAM expansion has 32 million transistors dedicated to RAM while the Z80 CPU still has only 8500 transistors.
