Nintendo GAME BOY Programming Manual page 174

Game Boy Programming Manual
Command: MASK_EN (Code: 17h)
Function: Masks the DMG window.
d7
1
00h
d7
01h --
* 2h- Fh filled with 00h.
Note: When masking is performed at the start of the game, it should be
performed after the DMG reset is canceled and around the time that the
DMG screen is displayed on SGB. (The timing of the command should
be adjusted so that it is issued after a wait of several frames.) Without
this timing, the screen may be momentarily be displayed in
monochrome.
Note: Masking with an argument (01h) of 10h or 11h is prohibited during a
game.
Command: PAL_PRI (Code: 19h)
Function: Specifies the priority of the color palette for the application and the color palette selected
by the player.
0 1 1 1 0 0 1
-- -- -- -- --
d0
Number of packets: 1h (fixed)
Command code: 17h
d0
00: Cancels masking
01: Freezes the screen immediately before
masking. (No transfers to Super NES
VRAM are performed from after the
command is issued until masking is
canceled.)
10: Masks by setting all SGB color palette
color codes to black.
11: Masks by setting all SGB color palette
color codes to the same color (color of bit
00).
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