Nintendo DMG-01 Manual - Page 55

FF43 SCX, FF44 LY, FF45 LYC, FF46 DMA

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Game BoyTM CPU Manual 2.13.1. I/O Registers 34. FF43 (SCX) Name - SCX Contents - Scroll X (R/W) 8 Bit value $00-$FF to scroll BG X screen position. 35. FF44 (LY) Name - LY Contents - LCDC Y-Coordinate (R) The LY indicates the vertical line to which the present data is transferred to the LCD Driver. The LY can take on any value between 0 through 153. The values between 144 and 153 indicate the V-Blank period. Writing will reset the counter. 36. FF45 (LYC) Name - LYC Contents - LY Compare (R/W) The LYC compares itself with the LY. If the values are the same it causes the STAT to set the coincident flag. 37. FF46 (DMA) Name - DMA Contents - DMA Transfer and Start Address (W) The DMA Transfer (40*28 bit) from internal ROM or RAM ($0000-$F19F) to the OAM (address $FE00-$FE9F) by DP Page 55

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Game Boy
TM
CPU Manual
2.13.1. I/O Registers
34.
FF43 (SCX)
Name
- SCX
Contents - Scroll X
(R/W)
8 Bit value $00-$FF to scroll BG X screen
position.
35.
FF44 (LY)
Name
- LY
Contents - LCDC Y-Coordinate (R)
The LY indicates the vertical line to which
the present data is transferred to the LCD
Driver. The LY can take on any value
between 0 through 153. The values between
144 and 153 indicate the V-Blank period.
Writing will reset the counter.
36.
FF45 (LYC)
Name
- LYC
Contents - LY Compare
(R/W)
The LYC compares itself with the LY. If the
values are the same it causes the STAT to
set the coincident flag.
37.
FF46 (DMA)
Name
- DMA
Contents - DMA Transfer and Start Address (W)
The DMA Transfer (40*28 bit) from internal ROM or
RAM ($0000-$F19F) to the OAM (address $FE00-$FE9F)
by DP
Page 55