Technique · engine

Boot sequence

The code a console runs from its reset vector at power-on or reset, which readies the hardware and memory and then starts the game.

stubAlso: reset handler, power-on reset, reset vector, startup code, cold boot, warm bootUpdated 2026-10-23

A boot sequence is the first code a game runs. It puts the processor in a known state, waits for the video chip to settle, clears memory, and hands over to the game loop.

See also

Games

Every claim about this mechanic, by game (2)
Super Mario Bros.: The Lost Levels 1986The Lost Levels' boot, NMI and pause code (Start through MoveAllSpritesOffscreen) is Super Mario Bros.'s with these changes: Start sets mirroring through the disk drive's control register, keeps WorldNumber across the reset and sets the BIOS's IRQ flag; the NMI arms the drive's timer IRQ to split the status bar from the level, where Super Mario Bros. waits for the sprite 0 hit, and its VRAM address table is one table of 31 words where Super Mario Bros. has low and high byte tables of 19; PauseRoutine allows a pause in game-mode task 4 instead of 3, the game mode's task list having gained a disk task at its head. SpriteShuffler and MoveAllSpritesOffscreen are byte for byte the same, and the operating-mode dispatch differs only in its addresses.Code
Mega Man 5 1992Mega Man 5's reset begins with Mega Man 4's first 98 bytes, byte for byte at the same address ($FE00-$FE61): the interrupt, sound, and rendering shutdown, the wait through four vblanks, the PPU address precharge, the RAM clear, the sound queue's empty markers, and the PPU mask shadow. From the mapper setup on, the two differ.Code