x86 Assembly Language - Part 1

Question 1

Name the 3 aspects of computer design

Answer 1

Instruction Set Architecture (ISA), Computer Organization, and Computer Hardware

Question 2

Define Instruction Set Architecture (ISA)

Answer 2

ISA refers to the actual machine interface visible to a programmer, such as the instruction set, registers, memory organization, and exception (interrupt) handling.

Question 3

2 types of Instruction Set Architecture

Answer 3

Reduced Instruction Set Computer (RISC) architecture and Complex Instruction Set Computer (CISC) architecture and

Question 4

Features of RISC ISA

Answer 4

• Fixed length encoding (ALL instructions are the SAME length)
• Addressing modes are typically bases and displacements.
• Arithmetic & logical operations (ALU) can be performed on registers.
• The only instructions that can affect memory are load and store instructions.
• No condition registers
• RISC processors use less power and generate less energy (heat).
• Large number of registers (32, 64, or 128 usually)
• Register-intensive procedural linkage: registers used for procedure arguments, return values, and addresses.
• All processors in smartphones and tablets are of RISC architecture.

Question 5

Define load instruction

Answer 5

Move data from memory to a register

Question 6

Define store instruction

Answer 6

Move data from a register to memory

Question 7

Define load-store architecture

Answer 7

Move data from memory to a register (load) or to memory from a register (store).

Question 8

Features of CISC ISA

Answer 8

• Variable length encoding (instruction length varies)
• More addressing modes, such as base, displacement, index, registers, sclae factors, etc.
• Arithmetic & logical operations (ALU) can be performed on registers OR directly on memory.
• Condition codes hold the side effects of instructions.
• CISC processors use more power and generate more energy (heat).
• Large number of registers (32, 64, or 128 usually)
• Stack-intensive procedural linkage: stacks used for procedural arguments, return values, and addresses.
• Intel IA-32 processors and other 64-bit versions of the ISA are of CISC architecture; found in over 90% of desktops and laptops computers.

Question 9

What are the 64-bit (8-byte) integer registers in x86-64?

Answer 9

%rax, %rbx, %rcx, %rdx, %rsi, %rdi, %rbp, %rsp, %rN, where 8 <= N <= 15

Question 10

What are the 32-bit (4-byte) integer registers in x86-64?

Answer 10

%eax, %ebx, %ecx, %edx, %esi, %edi, %ebp, %esp, %rNd, where 8 <= N <= 15

Question 11

What are the 16-bit (2-byte) integer registers in x86-64?

Answer 11

%ax, %bx, %cx, %dx, %si, %di, %bp, %sp, %rNw, where 8 <= N <= 15

Question 12

What are the 8-bit (1-byte) integer registers in x86-64?

Answer 12

%al, %bl, %cl, %dl, %sil, %dil, %bpl, %spl, %rNb, where 8 <= N <= 15

Question 13

What are the general-purpose 64/32/16/8-bit registers? What are they used for?

Answer 13

%rax/eax/ax/al, %rbx/ebx/bx/bl, %rcx/ecx/cx/cl, %rdx/edx/dx/dl, %rsi/esi/si/sil, %rdi/edi/di/dil, %rN/rNd/rNw/rNb, where 8 <= N <= 15. General-purpose registers are used to store integer data types and addresses.

Question 14

What are the stack management registers?

Answer 14

They are rsp and rbp - %rsp is the address of the top of the stack; it points to the last value pushed onto the stack. %rbp is a frame pointer; it points to the bottom of the stack frame of the function currently being executed.

Question 15

Define the mov instruction

Answer 15

The mov instruction copies N number of bytes from a source operand to a destination operand, where the size of the source and destination determines N.