The xyw virtual machine is able to access up to 64KiB of memory, which is the maximum that can be addressed using two bytes.
The memory is organized as follows
$0000: start of user memory
...
$ff00: devices
$ffff: end of memory [65535 bytes]
In other words, except for the last page (256 bytes) of memory that is reserved for devices, everything else can be used for user programs.
Having devices mapped in memory means that their addresses can be read and written using the standard LDB, STB, and similar instructions, exactly like any other address in memory, within the need of separate instructions.
When executed, programs will be loaded in memory starting at address $0000 automatically.
Consider that you can also configure a direct page anywhere in memory (by default it is set to $FF, corresponding to the devices page), which allows you to load and store values to a specific memory page using only one byte for addressing.
$0000: start of user memory
...
$ff00: devices
$ffff: end of memory [65535 bytes]
In other words, except for the last page (256 bytes) of memory that is reserved for devices, everything else can be used for user programs.
Having devices mapped in memory means that their addresses can be read and written using the standard LDB, STB, and similar instructions, exactly like any other address in memory, within the need of separate instructions.
When executed, programs will be loaded in memory starting at address $0000 automatically.
Consider that you can also configure a direct page anywhere in memory (by default it is set to $FF, corresponding to the devices page), which allows you to load and store values to a specific memory page using only one byte for addressing.