Cycle stealing

Abstract: A real-time power conservation apparatus and method for portable computers employs a monitor to determine whether a CPU may rest based upon a real-time sampling of the CPU activity level and to activate a hardware selector to carry out the monitor's determination. If the monitor determines the CPU may rest, the hardware selector reduces CPU clock time; if the CPU is to be active, the hardware selector returns the CPU to its previous high speed clock level. Switching back into full operation from its rest state occurs without a user having to request it and without any delay in the operation of the computer while waiting for the computer to return to a "ready" state. Furthermore, the monitor adjusts the performance level of the computer to manage power conservation in response to the real-time sampling of CPU activity. Such adjustments are accomplished within the CPU cycles and do not affect the user's perception of performance and do not affect any system application software executing on the computer.

Abstract: A power consumption reduction method and apparatus for a computer is described. The operating system running on the CPU of the computer determines when the CPU is not actively processing and generates a power-off signal to a control logic circuit. The control logic circuit then disconnects the CPU from the power supply. Pulses sent by a periodic timer or interrupts from input/output units are applied to the control logic circuit to at least periodically issue a power-on signal to the CPU. Power is supplied to the CPU for a given time period at every power-on signal. During this period, the CPU executes miscellaneous housekeeping chores including the polling of disk drives and determines when the CPU should resume normal processing. The control logic circuit also determines, at every power-on signal, whether the CPU is already on or being turned off. The control logic circuit will not issue a reset signal to enable the reset of the CPU if it is already on. If, however, the CPU has been turned off by the operating system, the control logic circuit will reset the CPU at every periodic power-on signal until CPU resumes its normal operation.

Abstract: A random access memory (RAM) device capable of performing logic combinations of new and previously stored data in a single memory access cycle. In contrast to conventional RAM data combination sequences, which involve a succession of read-modify-write cycles, the present architecture implements logical combinations of new RAM data with old RAM data during a single access cycle. In a preferred arrangement, decoding logic combines the new data with mode select signals to generate a set of FORCE 1, FORCE 0, COMP and NOOP control signals. The control signals regulate the bit line sense amplifier and logic to allow direct interaction with the bit line data during RAM addressing. The invention is particularly useful in graphic video display systems frame buffers where rapid pattern changes are difficult to implement using moderate speed and cost RAM devices.

Abstract: A method and apparatus are disclosed for performing adaptive run-time power management in a system employing a CPU and an operating system. A CPU cycle tracker (CCT) module monitors critical CPU signals and generates CPU performance data based on the critical CPU signals. An adaptive CPU throttler (THR) module uses the CPU performance data, along with a CPU percent idle value fed back from the operating system, to generate a CPU throttle control signal during predefined run-time segments of the CPU run time. The CPU throttle control signal links back to the CPU and adaptively adjusts CPU throttling and, therefore, power usage of the CPU during each of the run-time segments.