That's right you can use all the memory from PAGE which is usually but not always &E00 on a Master through to &8000 when in a shadow mode
Mdfs.net has good documentation for memory layout see
http://mdfs.net/Docs/Comp/BBC/AllMem
I can also recommend stardot.org.uk where there's a thriving ecosystem of developers and users
arjoll I'd love to have a compact but i suspect I'd be shot if i brought home another machine at this point. I'm sure somebody on stardot would give it a good home