Being a 6502-based system, the GameTank can read at, write to, or execute code from 65,536 different locations during a given cycle. The whole collection of these locations is called the “address space”, where “address” refers to the numeric ID of a given location. These locations are also often referred to as “memory” even though not all of the addresses point to a device you can store data to read back later.

The lowest 8,196 addresses provide general-purpose data storage. Data stored in this range will only be read and written by the main processor, without side effects.

Of special note within this section are the ranges $0000-$00FF, and $0100-$01FF, called the Zero Page and the Stack respectively. Addresses in the Zero Page can be accessed more quickly by special opcodes, and addresses in the stack are used by certain operations such as calling and returning from subroutines.

Although the memory map only dedicates 8K to this section, there are actually 32 kilobytes of general purpose RAM that can be used.