subject: Computer Engineering

Purpose

The objective is to review the programmers model, the assembly language, and the instruction execution cycle. To achieve these objectives, you will write a short program(s) satisfying the requirements below.

Description

Programmers Model

The programmers model of the MSP432 shows the current status of the MCU. As the name implies, what is described is a model of the MCU rather than a physical entity. Although the model components physically exist in the MCU, they are only a small part of a complex implementation necessary for the working controller.

Assembly Language

The symbolic language used to code source programs to be processed by the assembler is called assembly language. The language is a collection of mnemonic symbols representing operations (i.e., machine instruction mnemonics or directives to the assembler), symbolic names, operators, and special symbols. The assembly language provides mnemonic operation codes for all machine instructions in the instruction set.

Instruction Execution Cycle

The instruction execution cycle is the sequence of actions taken by the MSP432 to execute a set of instructions. There three steps involved in completing each instruction: fetch, decode, and execute. During the fetch stage, op-codes and operands are loaded from memory to the instruction register. The decode stage interprets each instruction as one predefined CPU action. For many instructions, this decode stage overlaps with the fetch stage: as soon as the op-code is fetched from memory, it is decoded. Once the necessary op-code and operand are loaded into the Instruction Register (IR), the MCU moves into the execution stage. During this stage, the decoded instruction is executed.

Procedure

1. Understanding the CCR

Write code that will: 1) load register r0 with 0xFFFFFFFF and, 2) add 1 to r0 store the result back into r0. In your report, after execution indicate what is in register r0 and what relevant flags (i.e., N, Z, V, and/or C) are set in the PSR after execution?

2. Instruction Execution Cycle

During the lecture, we stepped through the execution cycle of a simple processor (Lecture 4). Recall that the object code is represented in memory. Please use the commands LDR and STR to load and store a value of your choice. Then show in your screenshots the object code of these instructions. Finally, execute and show the relevant registers and memory locations in your screenshots. In your report, indicate how many cycles were needed to execute each instruction (i.e., this load will take an x amount of cycles, and this store will take a y amount of cycles).