Abstract: Logic circuitry (70, 80, 90) for performing fault detection in a microprocessor (5) is disclosed. The fault detection logic circuitry (70, 80, 90) may be implemented into a scheduler (50) in a floating-point unit (31). Mask register (M) bit positions (M.sub.0 through M.sub.7) store state information relative to registers (52) or other resources in the microprocessor (5) that is to be interrogated upon scheduling of an instruction. The instruction includes an encoded address communicated on register address lines (SA) that is received by the fault detection logic circuitry (70, 80, 90). Pass gates (72) are controlled by the encoded address on the register address lines (SA) to generate a fault indicator (FLT). Partitioning of the decoding of the encoded address may be utilized for optimization of the fault detection operation.

Abstract: A Zener diode structure comprising a semiconductor substrate layer of a first conductivity type, a first epitaxially formed semiconductor layer of the first conductivity type disposed on the substrate layer, a second epitaxially formed semiconductor layer of a second conductivity type disposed on the first semiconductor layer, a third semiconductor layer of the first conductivity type disposed over the second semiconductor layer, a buried layer of the first conductivity type disposed between and contacting the second and third semiconductor layers and a semiconductor contact region of the second conductivity type extending between and contacting a surface of the third semiconductor layer and the buried layer, the semiconductor contact region being an anode of a Zener diode, the buried layer being a cathode of the Zener diode.