I got a VB in from a PVB member with a very strange problem, it works fine with all the games he and I can throw at it, except for Bound High! which is for certain a problem with the mainboard.
I swapped out the displays with a VB head unit I have and the displays do not give problems, while my displays do show the same problem on the VB unit I received to repair.
The problem is that when the precaution texts are supposed to show, both screens just display a full red screen and text cannot be read in other parts of the game. I tested it with a Flashboy (non plus version) and repro copy of Bound High! and both had the same problem.
TheForce81 wrote:That would mean that not every mainboard is created with the same chips?
Not really… basically, when a chip is first powered on, or reset, some registers are guaranteed to be in a specified state (i.e. the Program Counter will be set to the Reset Vector), while others are simply left untouched. It would take a lot of extra circuitry inside the chips to put every register and memory location into a known state at reset, so those that aren’t important get left in an undefined state, expecting the program to write them. Obviously they’re still 0 or 1, but simply depend on what values the transistors latch to when powered up.
In this case, most systems usually go to 0, but yours apparently usually goes to 1. It could be a sign that your chip is “lower quality” (maybe the chip was poorly fabricated, has excessive leakage, etc)… but it’s certainly not operating outside of specifications. Basically, it’s the same as powering up a RAM chip and reading back the contents before writing anything. The bits aren’t guaranteed to be all 0 or all 1.
This is something that would have benefited the Bound High! reproduction cart run. It would be nice to see a ROM patch released that fixes this issue for FB+ users, who may experience it.
It is a very nice find indeed and very insightful information!
So to summarize what is going on here, it basically is a bug in the current BH! ROM but it doesn’t affect most VB’s because they sort of accidentally reset to a 0 state while other VB’s could load 1 state which causes the background to be set incorrectly which causes this issue.
Thanks everyone for all the input which eventually led to DogP’s conclusion.
Nice bit of sleuthing there, DogP! It’s barely tested (the ROM booted to the warning screen, but I didn’t go past it), so let me know if it doesn’t fix the problem, or if it causes other problems. I added the needed register init to the most obvious place, so it should be fine.
Thanks Runnerpack, it works great, tried it 5 times powering off and on removing the cartridge and not removing it. Will test some more this evening when I come back home from work, but for now it seems to do the trick and the game works fine (no hangs on real hardware with FB).
Sorry to wake an old thread for its slumber but I thought I could contribute something interesting regarding the patched ROM.
I picked up a second VB to practice repairs on and was getting the red screen issue upon boot-up. The patched ROM looks great on this system. I did run into an issue, however.
On the plasma stages, the enemies that are supposed to appear don’t. Anyone else run into that problem?
If you need me to do more testing let me know. I couldn’t get past the first plasma stage without seeing what was supposed to be there. I can always find a way to get it done though if it is needed.
