CS301: Computer Architecture

Watch this lecture, which is the third video of the series of video lectures on the design of a simple processor. This lecture explains how to build the control part of the MIPS architecture that is required to process a subset of MIPS instructions. This builds on the datapath design from the last lecture. That datapath design approach started with a design for the R class instructions with operands in registers, such as add, subtract, 'and', 'or', and 'less than'. It then included the other instructions, one at a time, and incremented the design to accommodate them. In this video lecture, an alternative approach is used to arrive at the same design. Here, the datapath for the arithmetic and logic instructions is designed. Then, the data path for the store, then for the load, then the branch on equal, and, finally, the jump are designed individually. Next, datapath design for all eight instructions is the union of the five individual designs. The control signals for each instruction are identified and combined to form a truth table for a controller, which is implemented using a PLA (program logic array). The video concludes with a performance/delay analysis of the design to show the limitations of a single cycle datapath. Next, we will look at pipelining for increased performance.