Demo causes WinUAE A500+ config to stop

[Leffmann]

This demo will cause WinUAE to stop completely during the first few seconds when run with quickstart non-expanded CE A500+ configuration, but runs fine on f.ex A500 512+512 config. This happens on several versions from 2.3.0 up to and including 2.4.2 beta 9.

There's also a graphics bug that looks like a bad bitplane modulo setting appearing 5 or so minutes into the demo, but I can't tell if it's because of WinUAE.

[Toni Wilen]

Coder for some strange reason decided that $1000 is safe place to copy code when interrupts are still enabled..

KS1.x = it is sort of unused.
2.0+ = part of execbase gets overwritten.. Things go bad soon, it gets worse when supervisor stack and PC finally start pointing to custom registers causing all kinds of weird blitter register writes that confuses something too much. (Will be fixed, of course)

btw, this kind of crash causes those strange sounds and color flickers on real Amigas too. I am sure everyone has seen those few times..
EDIT: also usually includes display going out of sync and monitor making strange noises if ECS chipset (=programmable refresh rate registers getting set to total bogus values)

Modulo problem: ECS required.

(btw, too boring demo..)

EDIT: Fixed, infinite loop caused by max hpos being 256 which isn't normally possible.

[Leffmann]

Is the modulo problem because it's trying to use the extended blitter size registers in ECS Agnus? And is the ECS Agnus the one that's also called "Fat Agnus" which can address 1M and also has the extra genlock features and border blanking?

[Toni Wilen]

Originally Posted by Leffmann

Is the modulo problem because it's trying to use the extended blitter size registers in ECS Agnus? And is the ECS Agnus the one that's also called "Fat Agnus" which can address 1M and also has the extra genlock features and border blanking?

No, it requires new ECS Agnus bit number 1 in DDFSTRT and DDFSTOP. Ignored by OCS version. Note that AGA.guide does not mention this new bit for some reason.

ECS Agnus usually means 1M or 2M Chip capable versions of Agnus chips.
EDIT: AFAIK "Fat Agnus" means PLCC Agnus ("Slim" being the A1000 DIP version). 1M+ Agnus is supposed to be "Fatter" Agnus or something..

No part 2. It is Denise (ECS version) that has ECS genlock and border blanking features. Only ugly ECS superhires requires both ECS Denise and ECS Agnus.