Agnus, Fat Agnus, Fatter Agnus pinouts/schematics?

[Kronos]

The A1000 (and A2000A) Agnus is really functional the same as the "Fat Agnus" used in early A500s and A2000Bs. Both come in seperate PAL and NTSC versions and support only 512k chipmem.

The Fat-Agnus also included some additional logic that was build of discreetly on the A1000/2000A.

The Big-Agnus supports either 1 or 2 MB of chipmem is switchable between PAL and NTSC both in HW and SW and allows for bigger blits (but AFAIK noone ever made real use of that).

[Kronos]

If I remember correctly the stuff that went into Fat-Agnus was the logic for generating the RAM-Refresh. Piggybacking a Fat-Agnus onto an A1000 (or A2000A) would equire to disable/bypass this logic either in the Fat-Agnus or on the motherboard.

From  a SW point of view there is no way of telling a slimm-Agnus from a (non Big) Fat-Agnus.