English Amiga Board - View Single Post - Memory expansion into chipram, non destructive

Jope · 16 April 2020, 07:55

It exploits a feature of the ECS Agnus, basically it always sees the additional 512k from the trapdoor as Chip RAM even if the OS sees it as Ranger Fast.

The ACA500plus performs a realtime address translation so that the CPU thinks the RAM is in the Chip RAM area when in reality it is still at c00000 in hardware. The Agnus doesn't care either way.

16 April 2020, 07:55	#3
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,874	It exploits a feature of the ECS Agnus, basically it always sees the additional 512k from the trapdoor as Chip RAM even if the OS sees it as Ranger Fast. The ACA500plus performs a realtime address translation so that the CPU thinks the RAM is in the Chip RAM area when in reality it is still at c00000 in hardware. The Agnus doesn't care either way.