Linking 8 and 16 bit microcomputers using the ieee 488 interface bus

The IEEE 488 bus is fast becoming the data communications standard in instrumentation industries. A system developed at Cranfield Institute of Technology allows a DEC LSI-11, a Texas Instruments TMS 9900 based microcomputer and two KIM-1 hobbycomputers to be linked in a mini-network mode. This system is the subject of the paper. To detect possible data transmission errors a number of methods are considered and the checksum method is implemented. In the LSI-11 microcomputer data transactions for the two protocols, software polling and interrupt, are demonstrated. The hardware used to construct the interfaces is fully detailed and the logic of the software is described.