Microcomputer access to cross software systems

Abstract

Downline loading involves the transferral of information from the internal memory of one computer to the internal memory of another. For development microcomputer systems utilizing cross assemblers (i.e. non-resident assemblers), downline loading provides an extremely fast method of transferring cross-assembled files into the microprocessor's memory. The design for one low-cost method of linking a microcomputer system to a larger computer for downline loading is described. In this design, the microprocessor system is viewed as a teletypewriter (TTY) type device attached to the larger computer system. Software in the microcomputer controls the physical link between the two systems and is responsible for interpreting and storing files into the internal memory of the microcomputer. The implementation of such a system for downline loading an Intel 8080 based microcomputer system from files stored on an IBM 370/VM interactive Conversational Monitoring System (CMS) is described. Hardware details of the serial link between the two systems, as well as the software required, are discussed in detail. For applications involving several microcomputer development systems, methods of downline loading among microcomputer systems are also discussed.