Testing of microprograms using the lockheed SUE microinstruction simulator
Scott Davidson, William Tao · ACM SIGSIM Simulation Digest · 1976
Each microinstruction of a microprogram written for a horizontally microprogrammable machine can affect the machine state in quite complex ways. A microinstruction simulator that allows a microprogrammer to examine the entire processor state is a valuable tool in the testing of microcode. The debugging aids made available by the simulator, as well as the design technique used in the construction of a microprogram, will tend to determine the strategy used in testing the microcode. This paper describes one such simulator and a set of testing strategies found useful in working with it. The machine simulated is the Lockheed SUE, a 16 bit microprogrammable minicomputer. The SUE Simulator not only allows the display of the processor state, but allows most of the state to be modified by the user. A testing strategy using the features of the Simulator is presented for a microprogram written using bottom-up techniques. The Simulator is also shown to be useful in testing microprograms written using other methods, and in simplifying and speeding the testing process. Finally, the use of the Simulator in examining the effects of modifications to the processor on the microprogramming task is discussed.