Abstract: A multi-voltage circuit on a semiconductor chip including core circuitry driven by a power supply voltage equal to the voltage of a selected external device operating in connection with the semiconductor chip, and having input/output circuitry in selected regions for operating in connection with external devices having the same operating voltage and other external devices having a selected substantially lower operating voltage. Peripheral input/output circuit regions of at least first and second kinds are established for interfacing with the respective high and low voltage external devices. According to one version of the invention, the input/output circuitry directed toward interfacing with external devices operating at a particular voltage level is concentrated at a particular peripheral region in the periphery of the semiconductor chip. According to another version of the invention, multiple regions of input/output circuitry are established for external devices at the same voltage level.

Abstract: A method and apparatus for reducing power consumption by a display device includes monitoring time intervals between successive updates by video update circuitry and time intervals between successive uses by one or more user-interface devices, such as a mouse or keyboard. A first time-elapsed signal is generated if a predetermined time interval is exceeded between successive uses by the user-interface devices. A reset input to a first timer is connected to the user-interface devices to restart the timing with each use. A second time-elapsed signal is generated if the interval between successive video updates exceeds a second predetermined time period. Video updating resets the timer used to monitor the video update circuitry, but once the second time-elapsed signal has been initiated, a video update will not disable the signal. Rather, the second time-elapsed signal is latched until the use of a user-interface device.

Abstract: A thermal control system for variable speed microprocessor with a piecewise estimate of temperature change. The estimate is modeled after actual temperature change measurements of a microprocessor operating at low and high speeds and is recorded in a digital format in storage registers, one set of registers for each operating frequency. A counter counts sample microprocessor clock signals for a time over which the microprocessor speed is operating at a specific speed and provides a basic count signal. This basic count signal is incremented or decremented by comparison with stored values of the piecewise estimate of temperature change. As the basic signal increases or decreases, new slopes are provided to the counter for adjusting the basic count, upwards or downwards, depending on whether the system speed is high, intermediate or low. The adjusted counter output is also fed to comparators, which monitor a desired upper and lower temperature limit.