more RAM , how?

[HellCoder]

If we can connect a PPC/PCI/USB to our amiga, why hasn't someone made a hardware thing to expand our chipmem ?

Just a thought.

[HellCoder]

As if the original thought of replacing the 680x0 by a PPC doesn't sound nasty. I remember my original thought when I read the news about a possible PPC card for the amiga...

[HellCoder]

The contents of the chips aren't moved to a file, but the chips are instantly replaced with other chips standing by. Another memory map. This is what the old C64 did also.

So the custom chips would access the chip-mem as if they were never replaced, but in fact they are...

if this is possible is something else though

[HellCoder]

The controller/library would perhaps sit inbetween the allocmem function and store additional information required somewere that can tell the memory map being used in the allocated memory block. The controller would need to monitor the address lines and the chip accessing the memory ? And than quickly switch memory map if desired....

although I feel something is missing

Perhaps you could say,.. Paula has map one, and Denise map two giving them both 2 MB each ?

[HellCoder]

No, I'm sure there are more chips accessing chip-mem. The Kickstart rom perhaps. Maybe this can be solved by having a small part of the 2MB setup as 'shared' memory and accessible in all memory maps. Interrupt lines and stuff should also be taken care of I think.

I think it would be alot easier if you have fast-mem too so you can have the stack pointer there.
 

[HellCoder]

Would all that effort be any worth ?
Although I'm still sad such a thing was never made, now it's too late I think.

[HellCoder]

Uuh..
Both Denise and Paula have a hardware line indicating if they have a connection to the databus. (tri-state) Only one at a time can have access. If you would feed this line to a hardware working memory map switchbox you could seperate memory for Paula and Denise without any slowdown. The only problem would be if Paula and Denise communicate with each other through a memory.

Although I'm no expert.

[HellCoder]

The custom chips won't have to access > 2MB, that's the whole point of the memory map. The only thing that would change is the memory itself, but still located at the same memory address.

The only thing that you would do is to switch between maps whenever Paula or Denise has access to the databus / address bus. The switch can be taken from the tri-state of Paula/Denise. This would indicate whether Paula or Denise has access to the datalines

I think it would be possible with some extensive work but not worth the effort.

[HellCoder]

No, not exactly.
What you need to do is tweak the allocmem function too. You would have to indicate whether it is meant for Paula or Denise. Allocating memory for Paula would activate memory bank 2. Allocating memory for Graphics would activate bank 1. If you would then play a sample located within the 2MB range Paula will be activated when it wants to (DMA). The activation of Paula can be detected by looking at the hardware lines (tri-state, enable line). If this happens the memory bank would switch to the 2MB chips for Paula (sound) (bank 2)

So both sound and graphics are located from location $000000 to $001fffff (2MB?) but in different chips.

But then again, the effort isn't worth it.