basic os stuff

boot.asm

@@ -0,0 +1,70 @@
+[BITS 16]
+[ORG 0x7C00]
+
+KERNEL_SEGMENT equ 0x1000
+KERNEL_SECTORS equ 32
+boot:
+jmp 0x0000: .init
+.init:
+cli
+xor ax,ax
+mov ds,ax
+mov es, ax
+mov ss, ax
+mov sp, 0x7C00
+sti
+
+mov [boot_drive], dl
+xor ax,ax
+int 0x13
+
+jc .disk_error
+
+call load_kernel
+
+mov ax, KERNEL_SEGMENT
+mov ds, ax
+mov es, ax
+
+jmp KERNEL_SEGMENT:0x0000
+
+.disk_error:
+mov si, disk_err
+call print_str
+cli
+hlt
+load_kernel:
+mov ax, KERNEL_SEGMENT
+mov es,ax
+xor bx, bx
+
+mov ah, 0x02
+mov al, KERNEL_SECTORS
+mov ch, 0
+mov cl, 2
+mov dh, 0
+mov dl, [boot_drive]
+int 0x13
+jc .disk_error
+ret
+.disk_error:
+mov si, disk_err
+call print_str
+cli
+hlt
+
+
+print_str:
+lodsb
+or al, al
+jz .done
+mov ah, 0x0E
+int 0x10
+jmp print_str
+.done:
+ret
+
+boot_drive: db 0
+disk_err: db "Disk error", 0x0D, 0X0A, 0
+times 510 - ($-$$) db 0
+dw 0xAA55