varying together  From Alvin Despain

23. Prior to the invention of the '336 patent, the source of the system clock signal in a microprocessor system was typically an off-chip crystal, which generally has a fixed frequency. In contrast, the '336 patent teaches the use of a variable-speed oscillator circuit to provide a system clock that is on the same chip as the microprocessor, and which is therefore subject to the
same variations in operating conditions, such as temperature and voltage, and in manufacturing processes. As a result, these variations affect both the on-chip oscillator circuit and the
microprocessor, causing the speed of the oscillator and the range of speeds the microprocessor can operate at to vary together, ensuring that the output of the microprocessor remains valid.