A theoretical computer described by M. Morris Mano in his textbook. Features a very limited instruction set, used for teaching.
The Mano machine is a computer theoretically described by M. Morris Mano. There's no commercial implementation, but some schools use it for teaching students the basics of systems design and assembly programming.
As a programming platform, it features a limited assembly language with 32 commands. There are two registers - 16-bit accumulator (AC) and 1-bit carry flag (E). There are two addressing modes - direct access and indirect access with address being taken from memory. Conditionals are implemented by comparing the accumulator to zero and opionally skipping the next command. The arithmetic capabilities are limited, too - there's no subtraction, no multiplication or division, no bitwise operations except NOT and rotation by one.