Main Action Window - Nintendo DMG-01 - Game Boy Console Manual

TM
Game Boy CPU Manual

4.4. Main Action Window

The SGB cartridge that plugs into the SNES contains
a GB CPU. The SNES is able to video capture the video
output of this GB CPU and display it on the screen as
the main game action window. Since the SNES is only
doing a raw video capture it only knows about 4 levels
of grey coming from the GB CPU. In order to add more
than 4 colors to the main game action window, the SGB
software allows you to assign 1 of the 4 SGB color
palettes for each 8x8 tile position in this window.
"Block"($4), "Line"($5), "Divide"($6), "1Chr"($7),
and "Set Attr from ATF"($15) all are different means
for setting the palettes for each 8x8 tile location.
On reset, each 8x8 tile position defaults to SGB
color palette 0.
Commands $4-$7 are various methods for block-setting
the 8x8 tile color palettes. The "Set Attr from ATF"
($15) allows you to select 1 of 45 "ATtribute Files".
Each "ATtribute File" contains 90 bytes (20x18x2 bits).
By selecting an "ATtribute File", you can exactly
select 1 of 4 SGB color palettes for each 8x8 tile
location due to the fact that these files contain
2 bits of information for each 8x8 tile location.
by DP
4.4. Main Action Window
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