PEEK and POKE - POKEs As Cheats

POKEs As Cheats

In the context of games for many 8-bit computers, it was a common practice to load games into memory and, before launching them, modify specific memory addresses in order to cheat, getting an unlimited number of lives, immunity, invisibility, etc. Such modifications were performed using POKE statements. The Commodore 64, ZX Spectrum and Amstrad CPC also allowed players with the relevant cartridges or Multiface add-on to freeze the running program, enter POKEs, and resume.

For example, in Knight Lore for the ZX Spectrum, immunity can be achieved with the following command:

In this case, the value 201 corresponds to a RET instruction, so that the game returns from a subroutine early before triggering collision detection.

Magazines such as Microhobby published lists of such POKEs for games. Such codes were generally identified by reverse-engineering the machine code to locate the memory address containing the desired value that related to, for example, the number of lives, detection of collisions, etc.

Using a 'POKE' cheat is more difficult in modern games, as many include anti-cheat or copy-protection measures that inhibit modification of the game's memory space. Modern operating systems may also enforce virtual memory protection schemes to deny external program access to non-shared memory (for example, separate page tables for each application, hence inaccessible memory spaces).