rename first stage

boot0.s

@@ -0,0 +1,67 @@
+; BIOS puts our boot sector at 0000:7c00
+org 0x7c00  
+; We're (probably) in real mode
+bits 16 
+
+  ; Disable interrupts, fuck knows what an interrupt would do right now
+  cli
+
+  xor ax, ax
+
+  mov ds, ax
+  mov es, ax
+
+  ; Put the stack base at the address of our program text (stack will grow high->low away from it).
+  ; We're not doing anything with a stack right now but who knows we might want to later
+  mov ss, ax
+  mov sp, 0x7c00
+
+  ; Segment for VGA (0xb800 * 16 = 0xb8000)
+  mov ax, 0xb800
+  mov fs, ax
+
+  mov ah, 0x00
+  mov al, 0x03
+  int 0x10
+
+  ; Hi!
+  mov word fs:[0x0000], 0xc048
+  mov word fs:[0x0002], 0xc069
+  mov word fs:[0x0004], 0xc021
+
+  hlt
+
+  ; TODO: grab all the info we can from bios interrupts and deliver it to ths OS nicely
+  ; e.g. in a fixed memory location
+
+  ; TODO:
+  ; - Generate GPT in justfile
+  ; - Parse global parition table
+  ; - Load second stage from GPT partition with a particular UUID / name like GRUB does
+  ;   (it's Hah!IdontNeedEFI in GRUB)
+  ;   - https://en.wikipedia.org/wiki/BIOS_boot_partition
+  ; - Future work:
+  ;   - Boot from UEFI
+  ;   - Boot on non-GPT partitioned disk
+
+  ; MBR bootstrap field is 440 bytes long
+  %if ($ - $$) > 440
+  %error "exceeded mbr bootstrap field size"
+  %endif
+
+  ; Pad to the end of the MBR bootstrap field
+  times 440 - ($ - $$) db 0
+
+  ; Unique disk ID
+  dd 0x00000000
+  ; Reserved
+  dw 0x0000
+
+  ; Zero the partition fields
+  ; TODO: fill in the field pointing to the GPT table
+  times 510 - ($ - $$) db 0
+
+  ; Boot signature
+  db 0x55
+  db 0xaa
+