Hello.

-- clear screen
cls()

-- remap screen from standard
-- 0x6000 to 0x8000. does not
-- work.
poke(0x5f55,0x80)

-- plot a single pixel there.
pset(0,0,7)

-- should return 7, does not.
?peek(0x8000),0,64

I was not aware there was a limitation for poke(0x5f55),mempage to ONLY work for the regular screen (0x6000) and the spritesheet (0x0000) - no other memory location !

I would like to request, @zep, that the memory chosen for both poke(0x5f54) and poke(0x5f55) can be anything at all, especially allowing for 0x8000 0xa000 0xc000 and 0xe000

It would sure help me a lot in my code. All of these in fact: pset(), pget(), line(), rect(), rectfill(), circ(), circfill(), oval(), ovalfill(), cls(), print(), spr(), sspr(), and clip().

Would anyone else like this ability ?

Personally I would use the extended memory as source images, so I would especially like to put the spritesheet to >=0x8000. This would save a few memcpys in my code.
If it's also possible to use it as a render target, that would be cool but not absolutely necessary.
But since the map can already be moved to that region, I bet it's also possible for sprites and screen with some hidden trick...

Agreed, @hellfire.

Mostly I want to use extended memory so I can draw to it and then draw back the full screen at say $0x8000 as a 128x128 transparent sprite.

There are many interesting things you could do with this.