Built-in self-test

A built-in self-test (BIST) or built-in test (BIT) is
a mechanism that permits a machine to test itself. Engineers design BISTs to meet requirements such as:

• high reliability
• lower repair cycle times

or constraints such as:

• limited technician accessibility
• cost of testing during manufacture

The main purpose^{[citation needed]} of BIST is to reduce the complexity, and thereby decrease the cost and reduce reliance upon external (pattern-programmed) test equipment. BIST reduces cost in two ways:

1. reduces test-cycle duration
2. reduces the complexity of the test/probe setup, by reducing the number of I/O signals that must be driven/examined under tester control.

Both lead to a reduction in hourly charges for automated test equipment (ATE) service.