rdos/kernel/main.asm

cpu 8086

; Memory layout (starting from top)
%define self    0xF000

; A single sector for disk i/o
%define diskbuf (self-0x200)

; DWORD partition offset for C: and D:
%define parttab (diskbuf - (2*4))

%define stack   (parttab)

%define default_drive BYTE [0x5B]

%define fcb_size 31

org self
jmp init

banner:
  db "RDOS 2019-09", 0x0A, 0x0D, '$', 0

init:
  mov sp, stack
  mov default_drive, 0x01

  mov dx, banner
  call print_string

  mov dx, 0x79
  mov byte [0x79], 0x7F
  call read_buffer
  mov ax, [0x79]
  int3

  cli
.halt:
  hlt
  jmp .halt

init_program:
  db "HELLO.COM", 0

cpm_syscall:
  cmp cl, 0
  je init
  cmp cl, 1
  je console_input
  cmp cl, 2
  je console_output
  cmp cl, 9
  je print_string
  cmp cl, 10
  je read_buffer
  stc
  ret

%include "char.asm"

%include "exec.asm"
%include "fcb.asm"
%include "fcbparse.asm"
%include "drive.asm"
%include "log2.asm"