Z80 Basics

Registers

Instruction and Data Formats

From Steve Ciarcia's Build Your Own Z80 Computer:

Memory for the Z80 is organized into 8-bit quantities called bytes. Each program byte is stored in a unique memory position and is referenced by a 16-bit binary address.

Total direct addressing capability is 65,536 bytes (64K) of memory, which may be any combination of ROM (read-only memory), EPROM (erasable-programmable read-only memory), or programmable memory. Data is stored in little endian format:

[  D7  |  D6  |  D5  |  D4  |  D3  |  D2  |  D1  |  D0  ]
MSB                                                   LSB
(Most significant bit)            (Least significant bit)