Methods, apparatus, and products for processor fault isolation are disclosed that include sending, by an embedded system microcontroller to a programmable logic device (`PLD`) a selection signal identifying one processor for boundary scan operations; sending boundary scan input signals to be sent to the identified processor; multiplexing by the PLD the boundary scan input signals to the identified processor; and sending boundary scan output signals returned from the identified processor. Methods, apparatus, and products for processor fault isolation are also disclosed that include connecting two or more processors in a boundary scan test chain, the connecting carried out by a PLD of a computer, the PLD further connected to sense lines carrying presence signals indicating whether processors are present in the computer; and including in the chain all processors indicated present according to presence signals.