This reduces the potential to flicker, but creates two separate
memory areas in the high memory.
For applications which require a large continuous memory space in
high memory, atarixl-largehimem.cfg is provided. With high IRQ
activity or DL interrupt there might be flicker.
- First chunk checks system (if it's XL and memory is ok).
- Second chunk contains the contents for the shadow memory beneath the
ROM and copies the contents to their destination address.
It also moves the screen memory to low memory in front of the program.
The target 'atarixl' is to be used for Atari XL (and better) machines.
It will disable the OS ROM and enable the Shadow RAM available on
those machine.
Note: This commit is only the inital step towards for this goal that just
replicates the target 'atari' as a starting point!
The targets allow to run cc65 programs in the sim65 exection
einvironment. As there are no "real" i/o facilities there's no
need for header files. Paravirtualized entry points are mapped
to $FFF0 ff. There's a large cc65 progam area from $0200-$FFEF.
The binary format includes a one-byte header indicating the required
execution environment: The value 0 means 6502 and the value 1
means 65C02. The load adress for the binary is fixed to $0200.
Note: Running sim65C02 programs currently doesn't work bcause
sim65 doesn't actually implement 65C02 opcodes.
