In computer architecture, 16-bit integers, memory addresses, or other data units are those that are 16 bits (2 octets) wide.
Early 16-bit computers (c. 1965–70) include the IBM 1130,[3] the HP 2100,[4] the Data General Nova,[5] and the DEC PDP-11.
16-bit processors have been almost entirely supplanted in the personal computer industry, and are used less than 32-bit (or 8-bit) CPUs in embedded applications.
The instruction set was based on 32-bit numbers and the internal registers were 32 bits wide, so by common definitions, the 68000 is a 32-bit design.
A common example is the Data General Nova, which was a 16-bit design that performed 16-bit math as a series of four 4-bit operations.
4-bits was the word size of a widely available single-chip ALU and thus allowed for inexpensive implementation.
For this reason, most processors had special 8-bit addressing modes, the zero page, improving speed.
For example, the 68000 exposed only 24 bits of addressing on the DIP, limiting it to a still huge (for the era) 16 MB.