4.1.1 Program Memory Organization

The program memory space is organized in word-addressable blocks. Although it is treated as 24 bits wide, it is more appropriate to think of each address of the program memory as a lower and upper word, with the upper byte of the upper word being unimplemented. The lower word always has an even address, while the upper word has an odd address (Interrupt and Trap Vectors).

Program memory addresses are always word-aligned on the lower word, and addresses are incremented or decremented, by two, during code execution. This arrangement provides compatibility with data memory space addressing and makes data in the program memory space accessible.