1. PROF. JOHN ABRAHAM UTRGV
MIPS - RISC
PROF. JOHN ABRAHAM
UTRGV
Prof. John Abraham UTRGV

2. Prof. John Abraham UTRGV
MARS SIMULATOR
FIRST MAKE SURE YOU HAVE JAVA JDK, IF NOT DOWNLOAD AND INSTALL
DOWNLOAD MARS MIPS SIMULATOR FROM MISSOURI STATE UNIVERSITY
Prof. John Abraham UTRGV

3. Prof. John Abraham UTRGV
MIPS CODE C=A+B
.data #data used in this program A: .word 40 # set aside RAM memory for A and place 40 in it B: .word 30 # set aside RAM memory for B and place 30 in it C: .word 0 # set aside RAM memory for C and place 0 in it .text #code for this program lw $t0, A #load A from memory into a CPU register t0 lw $t1, B #load AB from memory into a CPU register t1 add $t2, $t0, $t1 #add a and b sw $t2,C # Store the result from the CPU register to memory #display results a0-a3 and v0,v2 used with functions li $v0, 1 #1 to display following integer(4 to display text) move $a0, $t2 syscall
Prof. John Abraham UTRGV

4. Prof. John Abraham UTRGV

5. Prof. John Abraham UTRGV

6. Prof. John Abraham UTRGV
How to use SYSCALL system services
Step 1. Load the service number in register $v0. Step 2. Load argument values, if any, in $a0, $a1, $a2, or $f12 as specified. Step 3. Issue the SYSCALL instruction. Step 4. Retrieve return values, if any, from result registers as specified.
Prof. John Abraham UTRGV

7. Expanded program receiving input and sending output. Slide 1
.data
outText: .asciiz "MIPS for C=A+B.\n Total stored in C is: "
A: .word 0
B: .word 0
C: .word 0
prompt1: .asciiz "Enter the number to store in A: "
prompt2: .asciiz "\Enter the number to store in B: “
Prof. John Abraham UTRGV

8. Prof. John Abraham UTRGV
Slide 2
.text
li $v0,4 #get ready to display the message
la $a0,prompt1
syscall #displays the first prompt
#read the first number and save it in A
li $v0,5 #5 to read integer
syscall
sw $v0, A
lw $t1,A #also put it in t1 for calculation
Prof. John Abraham UTRGV

9. Prof. John Abraham UTRGV
Slide 3
li $v0,4 #get ready to display the message 4 to display text
la $a0,prompt2
syscall #displays the second prompt
#read the second number and save it in B
li $v0,5 #5 to read integer
syscall
sw $v0, B #put input into memory location B and in register t2
lw $t2, B #by the way faster to move between registers. This is to show you how to bring from ram
add $t3,$t2,$t1
sw $t3, C #store contents of t3 in C
Prof. John Abraham UTRGV

10. Prof. John Abraham UTRGV
Slide 4
#display results
li $v0,4
la $a0, outText
syscall
li $v0,1
move $a0,$t3
Prof. John Abraham UTRGV

11. Prof. John Abraham UTRGV
MIPS ISA
MIPS WORD IS 32 BITS, so registers can hold 4 bytes.
0 to 31 registers, PC (incremented by 4), HI and LO
Ex Rformat instruction: add $t0,$s1, $s2 (computation)
Ex I format instruction: lw $t0, B (load store branch) memory can be given as register and offset like 24($s2)
Ex J format unconditional jump
Some registers are special like r0 holds only 0, can’t be changed
Instructional formats: R format, I format and j format
Prof. John Abraham UTRGV