Paperboy is a 1985 arcade game by Atari Games originally developed in 1984. Paperboy was ported to consoles and home computers, starting in 1986. It was ported to the BBC Micro and Acorn Electron (1986), Commodore 64 (1986), Commodore 16 (1986), Amstrad CPC (1986), ZX Spectrum (1986), Apple II (1986), TRS-80 Color Computer (1986), DOS (1988), Apple IIGS (1988), NES/Famicom (1988) (1991, Japan), Game Boy (1990), Game Boy Color (1999), Atari ST (1989), Amiga (1989), Atari Lynx (1990), Sega Master System (1990), Game Gear (1991), and Sega Mega Drive/Genesis (1991) (1992, Japan). More information at Wikipedia.

A trainer offers one or more cheats like unlimited lives, invincibility, more ammo etc. Because this is done during runtime a trainer is not to be confused with a savegame editor.