Technique · rendering

VRAM buffer

A queue in RAM of writes for video memory, which the game fills during the frame and copies to the video chip in vertical blank.

stubAlso: name table buffer, PPU buffer, VRAM update buffer, graphics buffer, PPU stringsUpdated 2026-10-23

Video memory can be written safely only between frames or with the screen off, and the time between frames is short. A game therefore queues the tiles, attributes, and palette entries it wants to change, and its vertical-blank code copies the queue to video memory.

See also

Mentioned in

Games

Every claim about this mechanic, by game (4)
Super Mario Bros.: The Lost Levels 1986JumpEngine, InitializeNameTables, ReadJoypads and UpdateScreen are Super Mario Bros.'s, instruction for instruction: JumpEngine is byte for byte the same, and the other three differ only in the addresses of their calls, jumps and tables.Code
Mega Man 2 1988Mega Man 2's _scrolling_vertical follows Mega Man's _scrolling_up_down: the same name table and attribute address math and the same loop writing four 8x8 tiles per 16x16 quarter. Mega Man 2 computes the 32x32 block's address from the screen number, where Mega Man looks the screen up in a pointer table and checks _special_blockset_collision for a block the disassembly labels removed; some of its RAM moved too. The rest of each region is different code.Code
Mega Man 4 1991Mega Man 4's name table buffer flush is Mega Man 3's drain_ppu_buffer, byte for byte (37 bytes). Mega Man 4 follows it with four short routines: two that change PPUCTRL and two that turn rendering off and on.Code
Mega Man 5 1992Mega Man 5's name table buffer flush and the four PPU routines after it are Mega Man 4's instruction for instruction; only the zero-page counter the rendering switches step differs ($EA in Mega Man 4, $F0 in Mega Man 5).Code