Computer expansion slot and associated logic for automatically detecting

Abstract

An apparatus and method for determining the types of expansion cards connected to the expansion slot connectors of a computer system. Detect signals are provided to decode logic for determining the types of expansion cards connected to the computer system. If the expansion cards are compatible the decode logic produces an output power supply signal that indicates what the voltage level should be for the power supply to the cards. If the cards are incompatible, the decode logic may not provide power to any of the cards or only provide power to some of the cards that are compatible. For computers that allow expansion cards to connect to the computer while the computer is powered on, hot-plug logic cooperates with the decode logic to establish power and communication with newly connected interface cards. The connectors in the computer do not include keys and thus interface cards without keys, as well as cards with different types of key arrangements can be connected to and communicate with the computer. A removable keyed adapter can be mated with the expansion slot connectors to effectively provide keys to the expansion slot connectors to ensure reliable connections between the interface cards and expansion slot connectors. The adapters can be keyed in variety of arrangements to match whatever keying arrangements are included on the interface cards. In an alternative embodiment, voltage drops are provided to quick switches to ensure signaling compatibility between different card types. Further, all expansion slot connectors can be keyed for only a subset of the possible card types available and thus reduce the logic necessary to ensure compatibility.