week 7 assembly language

Question 1

Machine Language

Answer 1

Bit patterns that are directly executable by computer.

Instructions that the CPU can understand

Question 2

Assembly Language

Answer 2

Symbolic representation of machine language.

Instructions are written in mnemonic ASCII

Only readable for humans

Question 3

Assembler

Answer 3

used to translate assembly program (.ASM) into machine code (.OBJ)

Question 4

Linking

Answer 4

Process of connecting several .OBJ files together into one executable program.

Question 5

Programming

Answer 5

Process f designing/writing/testing/debugging/maintaining the source code of computer programs.

Question 6

Variables

Answer 6

places to store information

Question 7

Loops

Answer 7

a way to “repeat” a portion of a program over and over again

Question 8

conditional control

Answer 8

a way for our program to change the natural flow of a program based on a condition.

Question 9

Subroutine

Answer 9

a function in a high level language

a group of instructions meant to perform a specific task like square a number

Question 10

Pointers

Answer 10

variable storing a memory address

Question 11

Dereferencing

Answer 11

act of using the memory address held onto by a pointer to read/write from the memory location held onto by that pointer.

Question 12

Assembly directives

Answer 12

provide an indication to the assembler of where it should place various blocks of code or data

Question 13

what i need to write if/else statement in assembly

Answer 13

1. loading constants
2. arithmetic
3. compare
4. branch
5. basic jump instruction
6. labeling in assembly

Question 14

what i need to write a subroutine

Answer 14

1. .FALIGN
2. Labels
3. JSR
4. RET
5. assembly directives

Question 15

What i need to access data memory?

Answer 15

1. LDR
2. STR
3. pointer
4. for loop

Question 16

How does an assembler program operates?

Answer 16

1. first phase: converts labels into offsets and removes comments
2. second phase: converts assembly code into machine code with ISA and save it to an object file (.OBJ)
3. Then when this code finishes, a “loader” program loads it into computer’s memory.

Question 17

what are 2 regions in the LC4 memory

Answer 17

1. User region:
   - programs run by users like MS Word.
   - Processes run in user mode with PSR[15] = 0 are not allowed to access
   OS locations in the memory
2. OS region:
   - Processes run in OC mode with PSR[15] = 1
   - Address x8200 first address of your OS

Question 18

.DATA

Answer 18

next values are in data memory

Question 19

.ADDR

Answer 19

set current address to the specified value

Question 20

.FILL IMM16

Answer 20

set value at the current address to the specified 16 bit value