Abstract: Improved techniques for controlling multiple media bays (expansion bays) of a computer system are disclosed. Status information (and possibly one or more control operations) for devices in media bays of a computer system can be displayed, for example, to identify devices that occupy the media bays and to indicate the removability of those devices. Software locks discourage a user from improper removal of media bay devices in a multiple media bay computer system. The software locks work not only during hot removal of locked media bay devices but also removal of locked media devices during a sleep state of the computer system. Also, a centralized media bay data storage area can be provided as well as a media bay driver for each media bay to permits easy access to information pertaining to the one or more media bays of the computer system.

Abstract: Power management techniques for external cache memories of computers are disclosed. The power management techniques operate to reduce power consumption of an external cache memory of a computer system by intelligently placing the external cache memory in a low power mode. In one embodiment of the invention, a computer operates using event loop and an idle loop. The computer generally remains in the event loop while there is activity that requires processing, but enters the idle loop when there is no activity so that power consumption is lowered. The power management techniques according to the invention reduce power consumption of the computer by placing the external cache memory in the low power state upon entering the idle loop, and then awakening the external cache memory as the microprocessor awakens or upon exiting the idle loop. The power savings provided by the invention are particularly suitable for use with battery powered computing devices.

Abstract: An electrical circuit and method for multiplying an analog input signal by a sinusoidal function having an instantaneous phase specified by a number signaled in binary format. As a sine wave generator, the binary number is supplied by a counter clocked at a multiple of the desired sine wave frequency. The most significant bit of the counter modulates the polarity of or actually constitutes the analog input signal which is then fed to a numerically-controlled attenuator driven by the less significant binary counter outputs. The attenuator has selectively switched resistors with values specifying a sine table of attenuation from 0 to 90 degrees. A particular resistor is selected by an analog multiplexer having paired complementary outputs so that over the range of less significant bit values, a full 180 degrees of the sinusoid is generated.

Abstract: A system for transmitting binary instruction or data words to or from a computer by control from a home base remote from the computer site, and characterized by the entry of signals into the computer or the extraction of signals from the computer performed by apparatus which directly connects to the computer console manual switches and indicator lights. A single telephone line forming two simultaneously active channels transmitting time-spaced pulses in opposite directions, by modems known in the art, is used as the communication link. A special purpose microcomputer directly connected to the main computer console acts figuratively to actuate the console push buttom switches in response to pulse train signals received from home base and representing single bits or multibit words. It returns to the home base a rapidly iterated and updated pulse train representative of the status of all console lights.