Ah, I still remember my A500. I still have the A1200 and an A4000. One of my favourite things was the Action Replay. Astounding that you could freeze your machine as the press of a button, poke around the memory, find images, sounds and music, and then carry on as if nothing had happened.
The keyboard was a dream. If I recall it actually had it's own co-processor.
And for the developers, who can forget the system calls that allowed you to put in a memory-resident program that survived the CTRL-Amiga-Amiga.
I'm off to have a read of the ROM Kernel Reference Manual for aulde times' sake.