English Amiga Board - View Single Post - Differences between the original A2000 and later B2000

Toni Wilen · 30 December 2012, 14:42

Seriously, rare models can have compatibility differences, for example A1000 (and A2000 because it is based on A1000 chipset) have 2 "features" that can (and will) cause strange side-effects with some programs:

1) "new" clock region is chipset address mirror: Mouse cursor on game "Hacker" (original, not patched) only moves on A1000 or A2000!
2) DIP Agnus has a bug that starts vertical interrupt 1 line later than documented. Few very old demos only work properly on A1000 or A2000.

Documented blitter bug probably causes no problems at all because it was documented in HRM.

Hardware bugs needs to be emulated or above programs would have never run on emulation! -> Emulation should always (at least in "compatible" mode) emulate all side-effects as accurately as possible.

30 December 2012, 14:42	#11
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,545	Seriously, rare models can have compatibility differences, for example A1000 (and A2000 because it is based on A1000 chipset) have 2 "features" that can (and will) cause strange side-effects with some programs: 1) "new" clock region is chipset address mirror: Mouse cursor on game "Hacker" (original, not patched) only moves on A1000 or A2000! 2) DIP Agnus has a bug that starts vertical interrupt 1 line later than documented. Few very old demos only work properly on A1000 or A2000. Documented blitter bug probably causes no problems at all because it was documented in HRM. Hardware bugs needs to be emulated or above programs would have never run on emulation! -> Emulation should always (at least in "compatible" mode) emulate all side-effects as accurately as possible.