At this point the 64K bytes of RAM in the Commodore 64 are accessible by the built-in 6510 central processor, OR 48K bytes of RAM are available for the Z-80 central processor. You can shift back and forth between these two processors, but you can NOT use them at the same time in a single program. This is possible because of your Commodore 64's sophisticated timing mechanism.

Below is the memory address translation that is performed on the Z-80 cartridge. You should notice that by adding 4096 bytes to the memory locations used in CP/M^® $1000 (hex) you equal the memory addresses of the normal Commodore 64 operating system. The correspondence between Z-80 and 6510 memory addresses is as follows: