A personal computer includes a frame unit and a top cover mounted to pivot upward and outward to the rear of the system, or alternately, upward to the side. One or more DASD storage devices may be mounted to extend downward from the top cover. A planar board is attached atop the lower side of the frame unit, where flexible mounting hardware allows the attachment of one of several types of planar boards. A central support structure includes a riser card plugged into a connector of the planar board, and a number of card connectors into which option cards can be plugged for electrical connection with the planar board. The central support structure also includes a bracket extending along the rear of the computer, having slots through which port connectors of the option cards can extend. The central support structure is held in engagement with the connector of the planar board by the top cover when this cover is closed. When the top cover is open, the DASD storage devices may be easily replaced, the central support structure may be unplugged from the planar board, and the planar board can be easily replaced or serviced. A front surface of the computer includes a door, which is opened by rotation outward and downward, to be slid inward, providing access for the replacement of media in the storage devices. This door and the top cover are separately lockable using a multi-function lock.