Abstract: A modular computer includes a portable computer module providing a first set of performance characteristics, an expansion module reversibly couplable to an exterior surface of the portable computer module to provide, in combination therewith, a second set of performance characteristics, and a docking module reversibly couplable both to the portable computer module singly and to the portable computer module when combined with the expansion module to provide, in combination therewith, a third set of performance characteristics. A method of altering the features of a portable computer includes providing a portable computer having a first set of features, operatively coupling the portable computer to a transportable base wherein the coupling provides a second set of features, and operatively connecting the portable computer singly or in combination with the transportable base to a stationary base, wherein the connecting provides a third set of features.

Abstract: A modular computer includes a portable computer providing a first set of performance characteristics, an expansion module couplable to the bottom surface of the portable computer to provide, in combination therewith, a second set of performance characteristics, and a docking module couplable to the portable computer through the expansion module to provide, in combination therewith, a third set of performance characteristics. A method of altering the features of a portable computer includes providing a portable computer having a first set of features, operatively coupling the portable computer to a transportable base wherein the coupling provides a second set of features, and operatively connecting the portable computer through the transportable base to a stationary base, wherein the connecting provides a third set of features.

Abstract: A portable computer is provided with a battery-carrying handle member which is connected to the computer housing by an attachment structure extending between the handle member and the housing. The battery is electrically connectable to various electrical power-consuming devices in the housing, and the handle member is rotatable relative to the attachment structure, about an axis spaced apart from the handle member, between (1) a storage position, (2) a carrying position, and (3) a keyboard tilt orientation. Abutment end portions of the handle member are engageable with the attachment structure in a manner limiting the total rotational arc of the handle member relative to the attachment structure.

Abstract: A computer accessory and associated method of manufacturing provides multiple functions for use with a portable computer. In a preferred embodiment, a computer accessory has a keyboard tilt mechanism, an external battery, and a carrying handle in a single unit detachable from the computer. The external battery is contained within the carrying handle, which is pivotably mounted with respect to the computer. Rotation of the handle is limited by external shoulders formed thereon.

Abstract: A battery pack for a computer system including static memory to maintain battery operating parameters and charge information, a real time clock (RTC) for measuring periods of non-use of the battery and a communication means to exchange the battery information with a microcontroller located in the computer system. The static memory, RTC and communication means is preferably in the form of a single RAM/RTC chip. The battery pack also includes circuitry to maintain power to the RAM/RTC from the battery if AC power is not available. The microcontroller detects the presence of the battery and retrieves the present time from the RTC, a timestamp indicating time or removal of the battery and other operating parameters and charge information from the battery pack, and controls the charging functions of the battery accordingly. The microcontroller also updates the charge information of the battery pack while performing other housekeeping functions of a DC-DC converter.

Abstract: A battery charger is provided for use in electronic devices such as a portable computer. When the electronic device is being powered by an external source of power, such as an AC adapter, the battery charger charges the batteries in the electronic device. First, the battery charger checks the batteries to determine if they are capable of holding a charge. Next, the batteries are fully charged. After the batteries have been fully charged, the battery charger maintains the charge on the batteries by supplying low current to the batteries. Moreover, since batteries that are not allowed to discharge tend to lose charge more quickly than batteries that are discharged and recharged often, the battery charger is capable of discharging and then recharging the batteries while the electronic device is being externally powered.

Abstract: A method and apparatus for driving a seismic hydraulic vibrator in which a conventional sinusoidal drive signal in modified in such a manner as to improve vibrator response parameters. The sinusoidal drive signal is modified such that in the regions of the signal proximate the reference axis, the signal will abruptly pass from one side of the reference axis to the other side of the reference axis. This modification is accomplished by summing a square wave signal with the sinusoidal signal to form a composite drive signal.

Abstract: An improvement for the drive control system of a vibratory sound source used in seismic exploration comprising apparatus for generating a feedback signal proportional to the instantaneous acceleration of the reaction mass structure of the sound source's hydraulic drive system. Degenerative feedback of the signal so developed is used to reduce distortion of the vibratory seismic signal imparted into the earth.

Abstract: The present invention provides a method and apparatus for controlling the response of a seismic vibrator during its actuation period. The sweep input signal is modified in response to an average of the force applied to the earth by the vibrator over at least one cycle of the sweep signal. Additionally, this modified drive signal may be further adjusted by selective adjustment of the amplitude of the signal within selected frequency ranges.