TPS $($Think$-$Pair$-$Share$)$ activity $1$: Discuss questions $16(50$ minutes$)$ while paired with your classmates

assigned by your TA $($you will be assigned to groups of $3-4$ students$)$ and record your answers in a text file

named tpsAnswers.txt under a section labelled $$TPS $1($

you will continue to use this file to record

your answers to all the TPS questions that follow in the lab handout$)$:

$1.$ Download $$MIPS$\_$Reference$\_$Sheet$$ from CatCourses. We will need to refer to this sheet to

complete all the exercises in this lab.

$2.$ Load proc$1.$s in MARS and study the code. This is similar to compare.s from Lab $06.$

$3.$ After assembling the program, study the Text Segment window and see how your source code is

translated into True Assembly Language $($Basic$)$ as well as machine code $($Code$).$

$4.$ In true assembly language, every single instruction can be translated into a machine instruction. How

many bits does a machine instruction contain?

$5.$ To utilize the limited number of bits efficiently, all machine instructions are categorized into different

types $($or formats$).$ How many types are there? What are they? Give $2$ operations for each type as

examples.

$6.$ Now, locate the instruction in line #$7$ of proc$1.$s$.$ Let us translate this instruction into machine code.

a$.$ What instruction type is this? How many fields does this type of instruction have? What are the

names of these fields?

b$.$ Refer to the MIPS sheet, what is the value of the

opcode of this instruction in hex? What register

is rs$?$ What is the value of this register in hex? What register is rt$?$ What is the value of this register

in hex? What is the value of

immediate in hex?

c$.$ Construct the machine code of

line #$7$ using the values obtained from part b$.$ Write your answer in

both binary and hex formats. You can verify your answer with the Code column in Text Segment

window.

$7.$ Now, let us convert a machine code to a MIPS instruction. Locate address $0$x$00400010$ from the Text

Segment window.

a$.$ What is the machine code at this address in hex? Convert this code into binary.

b$.$ From the binary version of this machine code. What is the instruction type? How can you tell? How

many fields are there in this instruction type? What are the names of these fields?

c$.$ According to the binary machine code, what is the value of each field in hex?

d$.$ Refer to the MIPS sheet, what operation is this instruction? How can you tell? What is the mapping

of the registers being used in this instruction?

e$.$ What is the final MIPS instruction? Is it the same as the Source Column in the Text Segment

window?

$8.$ Now, let us take a look at

line #$17$ of proc$1.$s$.$

Lab $09$: Machine Language

CSE$-031-01$ Points: $20$

a$.$ What format is this instruction?

b$.$ What are the values of opcode, rs$,$ and rt of this instruction in hex?

c$.$ What is the name of the target label if it takes the branch? What is the address of this label in hex?

$($Hint: you can find it in the Text Segment window.$)$

d$.$ So$,$ do we put this address as the value of the

immediate field of the instruction? Why?

e$.$ How do we find the value of the

immediate field? What is this value?

f$.$ What is the machine code of this instruction in binary and hex formats? Does your answer match

the Code column in the Text Segment window?

$9.$ Finally, let us convert the j instruction in

line #$20.$

a$.$ What format is this instruction? How many fields are there in this format?

b$.$ What is the opcode of this instruction in hex?

c$.$ To what

label and

address does this instruction jump?

d$.$ How many bits can you use in the address field of the instruction? How can we $$squeeze$$ the

address into this field? What are the reasons behind this approach? What is the value of the

address field in binary?

e$.$ What is the machine code of this instruction in binary and hex? Is it the same as what$$s in the

Code Column of the Text Segment window? here is code proc$1.$s $.$data

str$1$: $.$asciiz "Less than

$"$

str$2$: $.$asciiz "Greater than or equal to

$"$

$.$text

# TPS $1$ part $6$

addi $s$0,$ $zero, $25$

li $v$0,5$ #read value from user

syscall

move $s$1,$ $v$0$

# TPS $1$ part $7$

slt $t$0,$ $s$1,$ $s$0$

# TPS $1$ part $8$

bne $t$0,$ $zero, LESS

# TPS $1$ part $9$

j GREQ

LESS: li $v$0,4$

la $a$0,$ str$1$

syscall

j END

GREQ: li $v$0,4$

la $a$0,$ str$2$

syscall

j END

END: li $v$0,10$

syscall