Ayy

BITS 16
ORG 7C00h

start:
    cli

    mov ah, 02h
    mov al, 1
    mov ch, 0
    mov dh, 0
    mov cl, 2
    mov bx, loadLocation
    int 13h

    xor ax, ax
    push ax
    popf
    mov ds, ax
    lgdt [gdt_desc]
    mov eax, cr0
    or eax, 1
    mov cr0, eax
    jmp 08h:protectedModeBegin

BITS 32

protectedModeBegin:
    mov ax, 10h
    mov ds, ax
    mov ss, ax
    mov esp, 90000h

    mov [0B8000h], BYTE 'P'
    mov [0B8001h], BYTE 1Bh

    jmp loadLocation

gdt:
gdt_null:
    dq 0
gdt_code:
    dw 0FFFFh
    dw 0
    db 0
    db 10011010b
    db 11001111b
    db 0
gdt_data:
    dw 0FFFFh
    dw 0
    db 0
    db 10010010b
    db 11001111b
    db 0
gdt_end:

gdt_desc:
    dw gdt_end - gdt
    dd gdt

    times 510-($-$$) db 0
    dw 0AA55h

loadLocation:
    mov [0B8002h], BYTE 'L'
    mov [0B8003h], BYTE 1Bh

.loop:
    jmp .loop