Abstract: A computer bus interface suited to connecting an expansion bus to a computer's internal bus. The interface is capable of selecting and deselecting any devices coupled to the expansion bus by enabling and disabling buffers which intercept signals between the expansion bus and the internal bus.

Abstract: A method and apparatus for monitoring the voltage discharge of a battery power supply while under load, and to manage the power supply by accurately calculating the time the useful charge is nearly depleted, providing a series of warnings to the user-operator of that fact, and subsequently performing a system shutdown before a complete discharge of the battery. If the invention is applied to a battery power supply for a computer, the series of warnings enable the computer operator to transfer data from a temporary memory to permanent storage in the time interval between a warning signal and computer shutdown; and since computer shutdown is effected before the battery is fully discharged a battery-destructive phenomenon known as a polarity cell reversal is prevented.