Sporadic freezing of FFX - Cured by HDL mode 1

[dlanor]

There is an error in most HDL compatibility lists, claiming that Final Fantasy X is fully compatible without any mode switches. Most of the game is indeed compatible, and it is even possible to finish the game without experiencing the freezing problem. This is because it only happens when switching members of the active battle team, inside a battle (via L1 button). Those who never do that will never see the problem. It will also be hidden automatically for much of the early part of the game, as no team switching is possible then. The problem is further masked by the fact that it only occurs RARELY, making it very hard to verify the problem reliably.

When switching team this way, the normal behaviour is for the member being switched out to run off the battlefield, whereafter the one being switched in runs onto it, replacing the other character in the battle formation. When the bug strikes, however, the screen display will freeze while the 'old' member is still visible, and before the 'new' one becomes visible. From that point on, no gamepad manipulation will have any effect (not even 'soft-reset'), and the screen will remain frozen like this forever. The music continues playing, however, so the code isn't all smashed, but merely locked up in some eternal loop.

This freezeup is rather similar to what I experienced in "Shadow Hearts" when testing it with no mode switches, so I decided to try FFX too with mode 1 (which cures "Shadow Hearts"). This experiment was successful! Mode 1 does eliminate the freezing, although it is still possible to see a slight glitch in the animation on those occasions when the bug would have struck if no mode switches were used.

I tested this problem using the PAL version of FFX (SCES_504.90), but I suspect that all versions use similar code for these operations, and will therefore need the same fix to eleminate freezing.

Best regards: dlanor