Evolution of the Instructional Processor
Ronald J. Hayne, John Michael Moore · 2015
Most modern commercial microprocessors are too complex to be used as introductory examples.Many digital design courses and texts use hardware description language models of these processors, but they are often ad hoc.What is needed is a basic processor with sufficient complexity that can be modified, programmed, and tested.An instructional processor has been developed for use as a design example in an Advanced Digital Systems course at The Citadel.The initial architecture provides sufficient complexity to demonstrate fundamental programming concepts, and the entire system is modeled and simulated in VHDL.A collaborative project between the Department of Electrical and Computer Engineering and the Department of Mathematics and Computer Science has added new capabilities to the design, including expanded memory, additional instructions, and more addressing modes.Machine code from a compiler or assembler can also be uploaded without modification of the VHDL model.The instructional processor is now in its third iteration with additional capabilities, an updated controller design, and a new memory model.Feedback is very positive that the VHDL model and FPGA implementation of the processor illustrate fundamental design concepts without unnecessary complexity.The expanded project continues to achieve its goal as a valuable instructional tool for Advanced Digital Systems with future utilization as an implementation platform for a Compiler Design course.