Image Number 16 for United States Patent #4639863.
A self contained fixed rotating disk expansion board subsystem may be installed and connected at an expansion slot location of a host computer. The subsystem includes an enclosed head/disk assembly, and circuit elements mounted on a printed circuit board which includes a connector for connecting to the control, data and address buses of the host computer at the expansion slot location. The head/disk assembly is mounted to a mounting substrate which may be the circuit board or which may be a frame to which the circuit board is also attached. Input/output routines are preferably provided to enable the host computer to make use of the subsystem without software driver modifications in the host operating system.