80020750 : 00021400  SLL     00000000 (v0), 00000000 (v0), 10 (16),
80020754 : 00021C03  SRA     00000003 (v1), 00000000 (v0), 10 (16),
80020758 : 2862064A  SLTI    00000000 (v0), 00000000 (v1), 064a (1610),
8002075c : 14400005  BNE     00000001 (v0), 00000000 (r0), 80020774,
80020760 : 00008021  ADDU    00000001 (s0), 00000000 (r0), 00000000 (r0),
80020774 : 0C00A9AA  JAL     8002a6a8, 80020750 (ra),
80020778 : 00000000  NOP    

===================
===================

8002a6a8 : 8782008C  LH      00000001 (v0), 008c (800c5454 (gp)) [800c54e0]
8002a6ac : 03E00008  JR      8002077c (ra),
8002a6b0 : 00000000  NOP    

===================
===================

8002077c : 00021400  SLL     00000002 (v0), 00000002 (v0), 10 (16),
80020780 : 00021403  SRA     00020000 (v0), 00020000 (v0), 10 (16),

; ZAP check
; v0 = current CD, s0 = target CD

80020784 : 14500003  BNE     00000002 (v0), 00000000 (s0), 80020794,
80020788 : 3C02800C  LUI     00000002 (v0), 800c (32780),

; GOOD

8002078c : 080081E7  J       8002079c,
80020790 : 00001021  ADDU    800c0000 (v0), 00000000 (r0), 00000000 (r0),

; BAD

80020794 : A4505F84  SH      00000000 (s0), 5f84 (800c0000 (v0)) [800c5f84]
80020798 : 2402001D  ADDIU   800c0000 (v0), 00000000 (r0), 001d (29),

8002079c : 8FBF0014  LW      8002077c (ra), 0014 (801fff70 (sp)) [801fff84]




Interesting note:
Game caches file entries at boot time to its own structure

$8009B268 = E.XA  m:s:f

For DVD build, it's:
$76, $28, $13, $00

76:28:13

If it's 106:28:13 --> $a6, $28, $13


Also note that replacing E.XA with 1.XA / 2.XA / 3.XA only
works at boot or cd swap.

Because we avoid the disc swap nag routines, we're still stuck
with 1.XA and must write the m:s:f manually ourselves

