Signetics 2650

The Signetics 2650 was an 8-bit microprocessor introduced in mid-1975. According to Adam Osborne's book An Introduction to Microprocessors Vol 2: Some Real Products, it was "the most minicomputer-like" of the microprocessors available at the time.

Signetics sold development boards e.g. the PC1001 and its successor, the PC1500 "Adaptable Board Computer", ranging in price from A$165 to A$400. The chip by itself sold for around A$20. Several hardware construction projects and programming articles were published in magazines such as Electronics Australia and Elektor and related kits were sold by electronics stores. These factors led to its use by a number of hobbyists in many countries such as Australia, U.S.A., United Kingdom, the Netherlands and Germany.

The chip contained seven 8-bit general purpose registers, although only four were visible at any time. It was limited to a 15-bit address space (thereby addressing a maximum of 32 KB of memory), since the upper bit of a 16-bit memory reference was reserved to indicate that the indirect memory addressing mode was to be used (a minicomputer-like feature).