A computer system uses simplified device drivers for operating hardware devices. A simplified device driver for a hardware device of a given device type, such as a flatbed scanner, works with a system-supplied common driver for that given device type. The common driver and the simplified driver together function like a regular device driver. The simplified device driver implements a small number of entry point functions corresponding to a pre-selected set of operation commands "generic" to hardware devices of that given device type. When an application makes a request for an operation by the device, the request is passed through a device driver interface (DDI) to the common driver. The common driver then calls the entry point functions in the simplified device driver to carry out the requested operation.