Alien Breed Special Edition save states

[Skumball404]

I've been experiencing a lot of crashes trying to restore save states in this game (WHDLoad version). Namely trying to view the portable map or login to the ship's computer after restoring a state. This crashes to Workbench with a "resload_FlushCache" error having "modified the VBR".


The solution seems to be loading the first level and logging in to the first computer, then load the save state from there as it seems to restore a critical component to the game's memory.


I've also witnessed permanent alien sprite glitches when saving the state on the level transition screen, so wait until in-game or in a ship computer, and keep multiple saves in case something goes wrong.

[jotd]

I remember "completing" the game using ARIII savestates on my A500 back in the days

Specially the last maze level. Horrible.

[Mclane]

I'm probably wrong, but I seem to remember Toni mentioning issues with save states and WHD's.

No doubt JIT if on does not help..

[Anubis]

IIRC save states for WHDLoad are not completely supported, meaning - you play at your own risk. From what I remember, save state and HD position/files can mismatch, crashing Amiga. Just use ADFs if you plan to use Save States. (that is what I do )

[Mclane]

Ah, good, nice to know it wasn't my memory playing tricks..

[Skumball404]

I use an A1200 config with fast ram for WHDLoad, faster but cycle-exact clock speed and no JIT.

From what I have learnt, the recent A500 Mini uses WHDLoad, save states and includes this game. I wonder how it performs on that platform using the save states.

[Skumball404]

Footage from the A500 Mini version of the game shows that upon loading the second level, the screen immediately transitions to the level map as if the player had purchased the Remote Location Scanner and pressed 'M' to view the map. I assume the problem was identified so something happens in the background to load in the missing piece before opening the ship's computer/map into memory, so a crash never occurs.

[Toni Wilen]

Originally Posted by Skumball404

This crashes to Workbench with a "resload_FlushCache" error having "modified the VBR".

I can debug this if someone first tells me what does this message mean in practise?

[Skumball404]

Originally Posted by Toni Wilen

I can debug this if someone first tells me what does this message mean in practise?

To be precise, the exact message reads as follows:
" Installed program has modified the VBR, detected on entering via 'resload_FlushCache'. "

[Toni Wilen]

I know what it technically means but it makes no sense because VBR (68010+ CPU register) is restored with statefile.

[jotd]

whdload checks that program doesn't change some special locations whenever it has a chance (not in interrupts, though)

When the slave flushes the caches (after loading for instance), whdload checks that the program didn't write into VBR registers (the VBR that whdload installs to supervise zero page interrupts) just in case the machine doesn't have a MMU installed.

[Toni Wilen]

Yeah, but VBR is obviously restored (or nothing would work) which makes this confusing...

Does it work if you save state when in games menu screen. Quick emulator immediately after saving. Then restore state directly. Does game work or still crash when it starts loading new data?

Does WHDLoad PRELOAD parameter change anything?

[jotd]

preload should definitely be used just because save states and hard disk read dont mux too well

[Skumball404]

Originally Posted by Toni Wilen

Yeah, but VBR is obviously restored (or nothing would work) which makes this confusing...

Does it work if you save state when in games menu screen. Quick emulator immediately after saving. Then restore state directly. Does game work or still crash when it starts loading new data?

Does WHDLoad PRELOAD parameter change anything?

Saving a state within the ship computer menu on the first level, quit emulator, reload state, logout of computer and log back in still crashes.


Uncommenting Preload still crashes.

[jotd]

do you have JIT enabled by chance?

[Skumball404]

Originally Posted by jotd

do you have JIT enabled by chance?

Not in this case: A stock A1200 with a cycle-exact 42.562740 CPU frequency (6 x A500 @ 7.093790), rev 40.68 kickstart ROM, 4MB Z2 Fast memory, Workbench 3.1 rev 40.42 on an HDF at DH0 and PC-linked folders on DH1-DH3 for Retroplay's pre-installed games including the latest Alien Breed Special Edition (1998), WHDLoad v18.7.

[jotd]

ok

Have you tried other save states of other games?
Have you tried running the game from hardfile instead of windows partitions?

[Skumball404]

Originally Posted by jotd

ok

Have you tried other save states of other games?
Have you tried running the game from hardfile instead of windows partitions?

While some games seem to load correctly in some places, Cannon Fodder produces similar VBR errors by saving states during level transitions, such as during the helicopter animation before each mission. Reloading a state during the helicopter scene produced a 'resload_LoadFileDecrunch' error (uncompress data in memory according to the WHDLoad website). That time WinUAE warns of saving a state.

The HDF version of Cannon Fodder seems to work correctly, but I haven't found an HDF of Alien Breed to test that game.

As others have suggested it seems like a combination of save states and WHDLoad is the issue.

[Don_Adan]

I can suspect that problem is related then new/different interrupt routine is used for different parts of this game (old one interrupt is overwritten by new interrupt). And WinUAE dont restored/set correctly something related with VBR.

[jotd]

well, copy the Alien Breed files to a mounted HDF and you're done.