1. CS 286 Computer Organization and Architecture
First Programming Assignment
For MIPS R3000 Processor
Department of Computer Science
Southern Illinois University Edwardsville
Fall, 2018
Dr. Hiroshi Fujinoki
FirstProgram/001

2. Assembly Programming using MIPS R3000 CPU
What is MIPS R3000 Processor?
A 32-bit RISC CPU developed by MIPS Technologies Inc.,
R3000 CPU Chip
Manufactured by IDT
Used for high-performance desktops such as workstations
Many venders manufacture the chip (NEC, IDT, Toshiba)
R3000/001

3. Assembly Programming using MIPS R3000 CPU
The process of assembly programming
We start from here!
SPIM Simulator
does these for us
R3000/002

4. w/ “.asm” file extension
CS 286 Computer Organization and Architecture
Start developing your first assembly program using SPIM
Your source code file
w/ “.asm” file extension
Prepare your source code
Step #1
Three major components in your SPIM program
“Test.asm”
(1) Data Section
(2) Program Definition
(3) Program Body
FirstProgram/001

5. CS 286 Computer Organization and Architecture
“#” indicates an in-line comment
Overview: an assembly program source code for SPIM
# ############################################################### #
# Test2.asm #
# #
# Sample assembly code No. 2 for testing SPIM Simulator #
# This sample program is just for understanding SPIM assembler #
.text
.globl main
main: li $s1, # Load "1" to register $S1
li $s2, # Load "2" (decimal "2") to register $S2
add $s0, $s1, $s # Add register S1 and S2 and save the
# result to S0 register
jr $ # Return from main (stop the program)
# END OF THE LINES ###############################################
“.text” label declares the beginning of
your assembly program source code
Declaring your program body name
The program body
Assembly
instructions
Stop your assembly program
FirstProgram/002

6. CS 286 Computer Organization and Architecture
The three components in your SPIM program
1. “Data” Section
This section is “optional”
This is the place where you keep any constants in your program
- Error message
- Prompt message for user input
- Any constant, such as “3.14”
- Input/Output buffers (contents vary, but buffer size unchanged)
The data section is declared by “.data” assembler directive
SPIM assumes the data section at the beginning
- Because the program codes are supposed to be at the end
FirstProgram/003

7. CS 286 Computer Organization and Architecture
The three components in your SPIM program (continued)
2. “Program Definition” Section
This is the place where you declare your assembly program
The program definition section is declared by “.text” assembler directive
The beginning label of your assembly program declared
by “.globl name_of_your_beginning_label”
 The program definition section should be the simplest (and shortest)
We will see this in examples later
FirstProgram/004

8. CS 286 Computer Organization and Architecture
The three components in your SPIM program (continued)
3. “Program Body” Section
This is the place where you write your program (assembly instructions)
You must start with the beginning label you declared
- If you declare “.globl main” in program definition
- You must start your program with “main:” label
Your program should be stopped by “jr $31” instruction
 If you forget that, the CPU continues to execute
What instructions will be executed?
We never know before.
FirstProgram/005

9. CS 286 Computer Organization and Architecture
Dissection: Program Body Section
Instruction field
Label
field
Comment
field
Beginning of a program
main:
jr $31 # Stop program
Your
program
Stop your program
FirstProgram/006

10. CS 286 Computer Organization and Architecture
This is when we start
PC-SPIM for the
first time
Open your program source code
Start using SPIM
FirstProgram/007

11. CS 286 Computer Organization and Architecture
Start using SPIM (continued)
Specify your source code file
FirstProgram/008

12. CS 286 Computer Organization and Architecture
Start using SPIM (continued)
Once assembly program is
opened, the four windows will
be automatically re-loaded
FirstProgram/009

13. CS 286 Computer Organization and Architecture
Close-Look (1): “Register” Window
“Register” window
Contents of registers
FirstProgram/010

14. CS 286 Computer Organization and Architecture
Close-Look (2): “Text Segment” Window
Assembler instructions
(from your source code)
Address for your instructions
Generated machine codes
(in Hexadecimal expression)
FirstProgram/011

15. CS 286 Computer Organization and Architecture
Close-Look (3): “Data Segment” Window
Address of major program
components are shown
FirstProgram/012

16. CS 286 Computer Organization and Architecture
Close-Look (4): “Message” Window
Messages from SPIM
Assembler are shown here
Most probably, the least important window ...
FirstProgram/013

17. CS 286 Computer Organization and Architecture
To run your program, press this button
FirstProgram/014

18. CS 286 Computer Organization and Architecture
Specify starting address of your assembly program (optional)
Text Segment Window
FirstProgram/015

19. CS 286 Computer Organization and Architecture
Examining registers for the result of program execution
FirstProgram/016

20. CS 286 Computer Organization and Architecture
The three components in your SPIM program (continued)
FirstProgram/017

21. CS 286 Computer Organization and Architecture
The three components in your SPIM program (continued)
The results of program execution
FirstProgram/018