Learn ASSEMBLY with Real Code Examples

section .data
    count db 0

section .text
    global _start

_start:
    ; increment count
    inc byte [count]
    ; print count (pseudo code, actual printing requires syscalls)
    ; toggle theme (simulated with a variable, 0=Light, 1=Dark)
    mov al, 0 ; isDark = 0
    ; increment, decrement, reset would be additional inc/dec/mov instructions

    ; exit program
    mov eax, 60 ; syscall: exit
    xor edi, edi ; status 0
    syscall

Demonstrates a simple counter simulation using Assembly instructions for x86 architecture (console-based).

section .data
    a db 5
    b db 3
    result db 0

section .text
    global _start

_start:
    mov al, [a]
    add al, [b]
    mov [result], al

    ; exit
    mov eax, 60
    xor edi, edi
    syscall

Adds two numbers using registers and stores result.

section .data
    n db 5
    fact db 1

section .text
    global _start

_start:
    mov al, [n]
    mov bl, 1
factorial_loop:
    mul bl
    dec al
    cmp al, 1
    jg factorial_loop
    mov [fact], al

    ; exit
    mov eax, 60
    xor edi, edi
    syscall

Calculates factorial of 5 using loop and register.

section .text
    global _start

_start:
    mov al, 0 ; fib0
    mov bl, 1 ; fib1
    mov cl, 0 ; counter
fibonacci_loop:
    ; compute next
    mov dl, al
    add dl, bl
    ; update registers
    mov al, bl
    mov bl, dl
    inc cl
    cmp cl, 5
    jl fibonacci_loop

    ; exit
    mov eax, 60
    xor edi, edi
    syscall

Generates first 5 Fibonacci numbers in registers (pseudo print).

section .bss
    counter resb 1

section .text
    global _start

_start:
    mov byte [counter], 1
count_loop:
    ; pseudo print counter
    inc byte [counter]
    cmp byte [counter], 11
    jl count_loop

    mov eax, 60
    xor edi, edi
    syscall

Counts from 1 to 10 using a loop.

section .data
    counter db 3

section .text
    global _start

_start:
    mov al, [counter]
    cmp al, 5
    jge skip_increment
    inc byte [counter]
skip_increment:

    mov eax, 60
    xor edi, edi
    syscall

Increment counter only if below 5.

section .text
    global _start

_start:
    mov al, 5
    mov bl, 10
    xchg al, bl

    mov eax, 60
    xor edi, edi
    syscall

Swaps two values in registers.

section .data
    flags db 0b00000001

section .text
    global _start

_start:
    xor byte [flags], 1

    mov eax, 60
    xor edi, edi
    syscall

Toggles the least significant bit of a byte.

section .data
    arr db 1,2,3,4,5
    sum db 0

section .text
    global _start

_start:
    mov al, 0
    mov ecx, 0
sum_loop:
    add al, [arr+ecx]
    inc ecx
    cmp ecx, 5
    jl sum_loop
    mov [sum], al

    mov eax, 60
    xor edi, edi
    syscall

Sum elements of a small byte array.

section .data
    a db 5
    b db 7
    result db 0

section .text
    global _start

_start:
    mov al, [a]
    cmp al, [b]
    jl set_flag
    jmp end
set_flag:
    mov byte [result], 1
end:
    mov eax, 60
    xor edi, edi
    syscall

Compare two bytes and set a flag.