Abstract: The present invention provides a removable telephone line surge protection circuit (104) for use by an electronic deuce such as a modem (102). The line protection circuit (104) protects the modem (102) against telephone line surges such as those caused by lightning strikes. In one embodiment of the invention, the line protection circuit (104) interfaces with test circuitry which is preferably located within the modem (102) in order to allow the modem (102) to determine if the line protection circuit (104) is still operational while the line surge protection circuit (104) is connected to the modem (102). The present invention also provides for a removable surge protection circuit that is a testable module when connected to an electronic device having automatic module test capability as presented in one aspect of the invention. The surge protection circuit also provides for status indication of its operability in order to allow device users to make a quick determination of whether or not the module is damaged.

Abstract: A modular housing for electronic apparatus includes an approximately C-shaped enclosure member having an inner portion and first and second sides. The enclosure member includes a male stacking enclosure connector on the first side; a female stacking enclosure connector on the second side; and a first cassette connector situated at the inner portion. A cassette for carrying an electronic apparatus engages the inner portion of the C-shaped enclosure member. The cassette includes a second cassette connector situated on the cassette suitable for engagement with the first cassette connector. A fan pulls air through the cassette through vents which mate with vents on the enclosure member.