18-bit

This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. Please improve this article by introducing more precise citations. (October 2009)

In computer architecture, 18-bit integers, memory addresses, or other data units are those that are at most 18 bits (2.25 octets) wide. Also, 18-bit CPU and ALU architectures are those that are based on registers, address buses, or data buses of that size.

18 binary digits have 262,144 (1000000 octal, 40000 hexadecimal) unique combinations.

Example 18-bit computer architectures

• Possibly the most well-known 18-bit computer architectures are the PDP-1, PDP-4, PDP-7, PDP-9 and PDP-15 minicomputers produced by Digital Equipment Corporation from 1960 to 1975.
• UNIVAC produced a number of 18-bit computers, including the UNIVAC 418 and several military systems.
• The IBM 7700 Data Acquisition System was an 18-bit computer.
• The BCL Molecular
• The NASA Standard Spacecraft Computer NSSC-1

References

• DIGITAL Computing Timelime: 18-bit architecture
• Architectural Evolution in DEC’s 18b Computers, Bob Supnik, 2006.