36-bit computing

In computer architecture, 36-bit integers, memory addresses, or other data units are those that are 36 bits (six six-bit characters) wide.

Starting in the 1960s, but especially the 1970s, the introduction of 7-bit ASCII and 8-bit EBCDIC led to the move to machines using 8-bit bytes, with word sizes that were multiples of 8, notably the 32-bit IBM System/360 mainframe and Digital Equipment VAX and Data General MV series superminicomputers.

The number of 36-bit machines rapidly fell during this period, offered largely for backward compatibility purposes running legacy programs.

Architectures that survived evolved over time to support larger virtual address spaces using memory segmentation or other mechanisms.

[5] By the time IBM introduced System/360 with 32-bit full words, scientific calculations had largely shifted to floating point, where double-precision formats offered more than 10-digit accuracy.

The 360s also included instructions for variable-length decimal arithmetic for commercial applications, so the practice of using word lengths that were a power of two quickly became commonplace, though at least one line of 36-bit computer systems are still sold as of 2019[update], the Unisys ClearPath Dorado series, which is the continuation of the UNIVAC 1100/2200 series of mainframe computers.