Programmable Built-In Self-Test (PBIST) is a memory DFT feature that incorporates all the required test systems into the chip itself.
The test systems implemented on-chip are as follows: PBIST was originally adopted by large memory chips that have high pin counts and operate at high frequencies, thereby exceeding the capability of production testers.
The purpose of PBIST is to avoid developing and buying more sophisticated and very expensive testers.
The interface between PBIST, which is internal to the processor, and the external tester environment is through the standard JTAG TAP controller pins.
It must also be able to perform different address generation schemes, different test data pattern generation, looping schemes, and data comparisons.