Technical Question regarding beginning address for FAST Ram on 68k (A500)

[Antiriad]

Does anybody know what should be the beginning address for the FAST ram? If we assume that we have 8MB of Fast Ram what should be the end address?

Does the Ram get addressed from the A0-A15 Address pins or is there an "internal" design trick(due to Chip/Fast Ram architecture) for doing that such as using upper address pins and doing bank swaps?

Thanks

Mike

[Doobrey]

According to the A500 memory map,
 $200000-$9FFFFF Space for AutoConfig memory

But, the actual start address depends on the type of expansion card!
 If done properly, it should use autoconfig to allocate some space in this area, so it could be anywhere in this range,depending on what else is plugged into the Amiga.
 
 There is no bank swapping, just simple decoding of the address lines, the expansion has it`s own ram controller to handle the rest.
 BTW, it`s A0-23 ..24bit wide address bus, 16bit data bus

[Antiriad]

Thanks for your response. From the Memory map you gave me it seems that the 0-200000 is reserved for Chip Ram and from 200000-9FFFFF for Fast. This adds up to 10MB of Ram. I Though the the maximum memory allocated for an A500 is 9MB?

Correct?

Mike

[Doobrey]

It depends..there is/was something called the MegaMiniChip (and a few variants) that gave the A500 &A2000 2Mb of chip ram by replacing the old 1mb agnus and adding another 1mb of ram.
 Without this, you get the 9mb limit you mentioned.

Then there`s the "Ranger" mem, which I think is about 2.5 mb too.. meaning you could max out an a500 to 12.5 mb of ram. :-)