Timing is wrong

[LemonBoy]

I've spent some time debugging Robocop2, it has a huge loop @ 0x3E7 that is too slow if compared to hardware. This makes the vblank fire in the middle of it and jump to some HRAM address with uninitialized memory which is supposed to contain a stub for starting a dma transfer, which is copied in by the game @ 0x157, right after the loop.

[Stewmath]

I've noticed a similar phenomenon in Star Wars. When pressing select, it freezes in a loop where it waits for LY==0. But the VBlank interrupt interferes, and when it returns LY is already at least 1. Which probably also indicates some timings are slower than they should be.

[LemonBoy]

Also, sometimes the lcd_update sets the event cycle to a negative number.
LemonBoy@63b76fb is a start for a syncronized world :)
I did a quick test against NO$GMB and looks like GameYob is off by ~1 M-State

[LemonBoy]

https://github.com/LemonBoy/GameYob/tree/gfxfix

This branch actually fixes picky games like Robocop2, Altered Space and such that require strict video timings. instr_timing still fails and Pokèmon Crystal isnt working anymore. Still a little step forward.

[Stewmath]

Another timing related issue: Super Mario Land's top statusbar (see #59). This also occurs in bgb.

[Stewmath]

This issue is old and a bit vague, so I'm closing it. I think most of these specific problems have been fixed.