600XL Memory Map

[flashjazzcat]

This has bothered me for a while and I never got around to asking anyone:

 

The stock 600XL is a 16K machine, right? Well, since the OS consumes 14K (plus 2K for hardware registers), how can this be the case? Does the 600XL not actually come with 32K of RAM, i.e. 16K RAM and another 16K under the OS? Is it 16K in the sense that the 800XL might be called a 48K machine?

Edited March 11, 2010 by flashjazzcat

[Wrathchild]

AFAIK the 600XL doesn't have the mem under the o/s just the 0-$3fff range.

[Rybags]

Just 16K, no more.

 

IIRC, it returns zero values for any "not present" RAM reads, where the 400/800 would give address bus echoes.

 

Additionally, the 1064 RAM expansion module has a full 64K, rendering the internal RAM redundant (it doesn't get used).

[flashjazzcat]

Right, I get it. $C000 to $FFFF is always ROM (apart from the hardware registers). Thanks. I just wanted to clear it up!

[Rybags]

You can switch it out of course, but kinda pointless since there's nothing else to map there.