SPC Version 0.9.5
In SPC you can define special system memory address constants that are treated like a variable with an absolute memory address.
A system address is simply a numeric constant preceded by the '@' symbol.
System constants can also be used to read and write to an area of shared memory that can be accessed via I2C from a device such as the NXT. The shared memory area from 0x20 - 0x3F is mapped to the byte addressed I2C 0x80 - 0xFF memory address range. This permits data to be exchanged between an attached NXT and the user program. See the Shared Memory page for predefined constants to use this area of memory.