Video; Tiles - Nintendo DMG-01 - Game Boy Console Manual

2.7.3. Low-Power Mode
; **** V-Blank Interrupt Routine ****
Vblnk:
push
push
push
push
call
ld
ld
pop
pop
pop
pop
reti

2.8. Video

2.8.1. Tiles

The main GameBoy screen buffer (background) consists
of 256x256 pixels or 32x32 tiles (8x8 pixels each).
Only 160x144 pixels can be displayed on the screen.
Registers SCROLLX and SCROLLY hold the coordinates of
background to be displayed in the left upper corner of
the screen. Background wraps around the screen (i.e.
when part of it goes off the screen, it appears on the
opposite side.)
An area of VRAM known as Background Tile Map contains
the numbers of tiles to be displayed. It is organized
as 32 rows of 32 bytes each. Each byte contains a
Page 22
af
bc
de
hl
SpriteDma
a,1
(VblnkFlag),a
hl
de
bc
af
Game Boy
; Do sprite updates
TM
CPU Manual
V 1.01