Abstract: A novel line-current protection circuit for detecting excessive line current from a telephone line and protecting line interface circuitry from the excessive line current is presented. The protection circuit is adapted to detect when an excessive current is present on the tip and ring lines indicative of the misconnection of the modem or other line interface device with a telephone network that presents an incompatible interface standard. The preferred embodiment appreciates the multimode hold current specifications throughout the world and evaluates the connection of the line interface circuit with a telephone line to determine the compatibility therewith. When excessive line current is detected, the line-protection circuit switches the vulnerable line interface out of the circuit. When compatible line current levels are detected, the present invention reconfigures the configurable hold circuit into its original operating (e.g., non-testing) state for call processing.

Abstract: In order to boot a portable computer, a smart key is required to be inserted into a PCMCIA card of the portable computer. Firmware in the PCMCIA card verifies that a smart key has been inserted. The portable computer will boot only when two conditions are met. The first condition is that the smart key, the PCMCIA card, and the portable computer all contemporaneously have the matching codes stored therein. The second condition is that the first condition is met and that a new random generated and encrypted code is successfully stored in each of the smart key, the PCMCIA card, and the portable computer. Until these two conditions are met, the portable computer will not boot. Once booted, access to certain coded files on the portable computer is denied if respective matching codes in the coded files are not also contained in the smart key. Also, the portable computer will not exit an idle, sleep, or power conservation mode until the two conditions are met.