rdos/kernel/main.asm

cpu 8086
org 0x0000
  db 0x55, 0xAA
optrom_length:
  db 0x00
  jmp optrom_init

str_vendor:
  db "Nero", 0

align 16
str_product:
  db "Nero DOS", 0

times (0x1A - ($-$$)) db 0
  dw pnp

align 16
pnp:
  db "$PnP"
  db 1 ; version 1
  db 2 ; 2 * 16 length
  dw 0 ; offset of next header
  db 0
  db 0 ; checksum (filled by fix-rom)
  dd 0 ; device identifier
  dw str_vendor ; manufacturer string
  dw str_product ; product name string
  db 0,0,0 ; device type string
  db 0x20 ; device indicator, bit for "read cacheable" set
  dw 0 ; boot connection vector
  dw 0 ; boot disconnect vector
  dw start ; bootstrap entry point
  dw 0 ; reserved
  dw 0

align 16
optrom_init:
  xor ax, ax
  mov es, ax
  mov di, 0x0060 ; vector (0x18 * 4 bytes)
  mov ax, start
  stosw
  mov ax, cs
  stosw
  retf

putc:
  push bx
  push cx
  mov ah, 0x0e
  mov bx, 0x0000
  int 0x10
  pop cx
  pop bx
  ret

announce:
  push cs
  mov ax, str_product
  push ax
  call printf
  db "%S (CS=%Xh)", 0x0A, 0x0D, 0x00
  add sp, 4
  ret

start:
  mov ax, cs
  mov ds, ax

  call announce

  ; clear memory until 0x01000
  xor ax, ax
  mov es, ax
  mov di, 0x500
  mov cx, 0xB00
  rep stosb

  call intr_init
  sti

  sub sp, 0x10
  mov si, sp
  mov word [ss:si+0x00], 0
  mov word [ss:si+0x02], 1
  mov word [ss:si+0x04], 0
  mov word [ss:si+0x06], 0x2000
  mov word [ss:si+0x08], 0x07fc
  mov word [ss:si+0x0A], 0
  mov word [ss:si+0x0C], 0
  mov word [ss:si+0x0E], 0
  mov ah, 0x42

  push ss
  pop ds
  call ramdisk_io
  push ax
  call printf
  db "AX=%X", 0x0A, 0x0D, 0x00
  pop ax

  add sp, 0x10

.halt:
  hlt
  jmp .halt

%include "ramdisk.inc"
%include "printf.inc"

%include "intr.asm"
%include "debug.asm"
%include "kprintf.asm"
%include "dosapi.asm"

_reloc_end:

align 512