* avr/z80.asm:

* avr/z80.asm:
  - Save partition sizes and check if sector to be read or written is in partition range.
  - read/write functions return error code to Z80 bios.
  - Some bugfixes and cleanups in (de)blocking code.
  - DRAM refresh interupt does nothing, if read or write cycle is in progress.
  - print_ultoa saves all used registers.

git-svn-id: svn://cu.loc/avr-cpm/trunk/avrcpm/avr@64 57430480-672e-4586-8877-bcf8adbbf3b7