Abstract: A driver circuit including of one or more fingers, or parallel driver circuits, senses for an overshoot or an undershoot condition of the signal transmitted onto a transmission line coupled to the driver circuit and compensates for such an overshoot or an undershoot by temporarily turning off the offending transition portion of the driver circuit, or finger portion. This is accomplished by turning off the transistor applying one of the two supply voltages coupled to the output transmission line. Effectively, the compensation circuitry within the driver circuit more closely matches the output impedance of the driver circuit to the impedance on the driven transmission line.

Abstract: A method and apparatus for accessing a register in a data processing system (10). In one form, the present invention uses a storage circuit (23) to act as a register copy (23) of the original register (33). An access to the register location may actually selectively access the original register (33), the register copy (23), or both the original register (33) and the register copy (23). Register select logic (70) is used to perform this selection function. Register select logic (70) may also be used to keep track of the current status of the contents of the original register (33) and of the contents of the register copy (23). Register select logic (70) may also monitor the internal state of data processing system (10).