System for coupling a host computer to an image scanner in which high

Abstract

Methods and apparatus for coupling a host system to an image scanner in which high-level functions are migrated out of the scanner control module up to the attached host system. The host system and the scanner, via its control module, communicate using a low-level control instruction set. The low-level control instruction set enables the host system to directly control the scanning process by reading and writing memory locations within the control module. The memory locations include data structures descriptive of control operations to be performed by the scanner control module as well as status to be reported from the scanner to the host system. The low-level control instruction set includes instructions generated by the host system requesting return of particular data from memory locations in the scanner control module as well as instructions requesting the writing of particular data to memory locations in the scanner control module. Host based elements translate high-level scanner commands received, for example, from application programs into corresponding sequences of low-level control instructions. In particular, the present invention may be advantageously applied to translate Hewlett-Packard Scanner Control Language (SCL) requests into low-level control instruction sequences (also referred to as Scanner Primitive Language or SPL). Shifting computation and memory requirements from the scanner control module to the host system substantially simplifies scanner control module design enabling production of lower cost scanning devices.