Then later on there was the Enhanced Chip Set and the Advanced Graphics Architecture.

On that note, i think the A500 my parents got me back in the day were a oddity. I distinctly recall it having 1MB chip ram, suggesting it had the ECS inside. But it shipped with Workbench 1.x rather than 2.x.

That wasn't an oddity. It would have shipped with Workbench 1.3. I had one just like it with the Fatter Angus chip that could address up to 1MB of chip RAM, although you could still configure it as 512K chip and 512K fast, which is what I did.

I can't remember whether you did the 1MB chip config with a dip switch or by cutting a track on the motherboard - I think it may have been the latter, which is probably why I didn't do it.

I had a weird Amiga 500. It had late OCS chipset, but on hardware level its Denise could display bitplanes from slow RAM (512 kB RAM expansion)! Unfortunately I never tested blitter, copper lists, sample playback etc. from this memory range, so no idea whether those worked as well. Of course all is DMA access, so my guess is they would have.

RAM was mapped at 0x80000-0x100000 from chipset point of view. CPU saw same data at 0xc00000-0xc80000.

Yep, I had the 500 too. They called the updated chip Fat Agnus.

Sounds like it could've been an A500+.

http://www.bigbookofamigahardware.com/bboah/product.aspx?id=...