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★ HARDWARE Manual ★ VDP2 User's Manual ★ Chapter 4 Scroll screen
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VDP2 User's Manual/Chapter 4 Scroll screen

■4.5 Character control register

The character control register selects the cell format and bitmap format, specifies the number of character (bitmap) colors, and specifies the character pattern or bitmap size. This is a 16-bit write-only register located at addresses 180028H to 18002AH. The value is cleared to 0 after power-on or reset, so be sure to set it.

CHCTLA 180028H
   15   
   14   
   13   
   12   
   11   
   10   
   09   
   08   
 -
 -
 N1CHCN1
 N1CHCN0
 N1BMSZ1
 N1BMSZ0
 N1BMEN
 N1CHSZ

   07   
   06   
   05   
   04   
   03   
   02   
   01   
   00   
 -
 N0CHCN2
 N0CHCN1
 N0CHCN0
 N0BMSZ1
 N0BMSZ0
 N0BMEN
 N0CHSZ

　

CHCTLB 18002AH
   15   
   14   
   13   
   12   
   11   
   10   
   09   
   08   
 -
 R0CHCN2
 R0CHCN1
 R0CHCN0
 -
 R0BMSZ
 R0BMEN
 R0CHSZ

   07   
   06   
   05   
   04   
   03   
   02   
   01   
   00   
 -
 -
 N3CHCN
 N3CHSZ
 -
 -
 N2CHCN
 N2CHSZ

　　　　　　

Character color number bit : Character color number bit
(N0CHCN2〜N0CHCN0, N1CHCN1, N1CHCN0, N2CHCN, N3CHCN, R0CHCN2〜R0CHCN0)
Specify the number of character colors for each screen. When displaying in bitmap format, specify the number of bitmap colors.

 N0CHCN2～N0CHCN0
 180028H
 bits 6-4
 For NBG0 (or for RBG1)
 N1CHCN1, N1CHCN0
 180028H
 Bit 13, 12
 For NBG1 (or for EXBG)
 N2CHCN
 18002AH
 bit 1
 For NBG2
 N3CHCN
 18002AH
 bit 5
 For NBG3
 R0CHCN2～R0CHCN0
 18002AH
 bits 14-12
 For RBG0

 N0CHCN2
 N0CHCN1
 N0CHCN0
 TV screen mode
 color format
 normal
 high resolution
 exclusive
 monitor
 0
 0
 0
 16 colors
 16 colors
 16 colors
 pallet format
 0
 0
 1
 256 colors
 256 colors
 256 colors
 pallet format
 0
 1
 0
 2048 colors
 2048 colors
 2048 colors
 pallet format
 0
 1
 1
 32768 colors
 32768 colors
 32768 colors
 RGB format
 1
 0
 0
 16.77 million colors
 Setting prohibited
 Setting prohibited
 RGB format
 1
 0
 1
 Setting prohibited (please do not set)
 1
 1
 0
 Setting prohibited (please do not set)
 1
 1
 1
 Setting prohibited (please do not set)
[Note] When used as RBG1, it cannot be displayed in dedicated monitor mode.

 N1CHCN1
 N1CHCN0
 TV screen mode
 color format
 normal
 high resolution
 exclusive
 monitor
 0
 0
 16 colors
 16 colors
 16 colors
 pallet format
 0
 1
 256 colors
 256 colors
 256 colors
 pallet format
 1
 0
 2048 colors
 2048 colors
 2048 colors
 pallet format
 1
 1
 32768 colors
 32768 colors
 32768 colors
 RGB format
[Note] When using for EXBG, when the setting value is N1CHCN1 = 1, N1CHCN0 = 1,
There will be 16.77 million colors.

 NnCHCN0
 TV screen mode
 color format
 normal
 high resolution
 exclusive
 monitor
 0
 16 colors
 16 colors
 16 colors
 pallet format
 1
 256 colors
 256 colors
 256 colors
 pallet format
[Note] 2 or 3 is entered for n in the bit name.

 R0CHCN2
 R0CHCN1
 R0CHCN0
 TV screen mode
 color format
 normal
 high resolution
 exclusive
 monitor
 0
 0
 0
 16 colors
 16 colors
 Not displayable
 pallet format
 0
 0
 1
 256 colors
 256 colors
 Not displayable
 pallet format
 0
 1
 0
 2048 colors
 2048 colors
 Not displayable
 pallet format
 0
 1
 1
 32768 colors
 32768 colors
 Not displayable
 RGB format
 1
 0
 0
 16.77 million colors
 Setting prohibited
 Not displayable
 RGB format
 1
 0
 1
 Setting prohibited (please do not set)
 1
 1
 0
 Setting prohibited (please do not set)
 1
 1
 1
 Setting prohibited (please do not set)

Depending on the number of colors in NBG0 and NBG1, a scrolling screen that cannot be displayed may appear. If NBG0 is set to 2048 colors or 32768 colors, NBG2 cannot be displayed.
If NBG0 is set to 16.77 million colors, NBG1 to NBG3 cannot be displayed.
If NBG1 is set to 2048 colors or 32768 colors, NBG3 cannot be displayed.

　　　　　

Bit map size bit (N0BMSZ1, N0BMSZ0, N1BMSZ1, N1BMSZ0, R0BMSZ)
Specify the bitmap size for each screen when displaying in bitmap format.

 N0BMSZ1, N0BMSZ0
 180028H
 Bit 3, 2
 For NBG0
 N1BMSZ1, N1BMSZ0
 180028H
 Bit 11, 10
 For NBG1
 R0BMSZ
 18002AH
 bit 10
 For RBG0

 NnBMSZ1
 NnBMSZ0
 bitmap size
 0
 0
 512 dots horizontally x 256 dots vertically
 0
 1
 512 dots horizontally x 512 dots vertically
 1
 0
 1024 dots horizontally x 256 dots vertically
 1
 1
 1024 dots horizontally x 512 dots vertically
[Note] 0 or 1 is entered for n in the bit name.

 R0BMSZ
 bitmap size
 0
 512 dots horizontally x 256 dots vertically
 1
 512 dots horizontally x 512 dots vertically

　　　　　

Bit map enable bit (N0BMEN, N1BMEN, R0BMEN)
Specifies whether to display the scroll screen in bitmap format.

 N0BMEN
 180028H
 bit 1
 For NBG0
 N1BMEN
 180028H
 bit 9
 For NBG1
 R0BMEN
 18002AH
 bit 9
 For RBG0

 xxBMEN
 Screen display format
 0
 cell format
 1
 bitmap format
[Note] xx in the bit name is N0, N1, or R0.

　　　　　

Character size bit (N0CHSZ, N1CHSZ, N2CHSZ, N3CHSZ, R0CHSZ)
Specify the character size when displaying the scroll screen in cell format.

 N0CHSZ
 180028H
 bit 0
 For NBG0 (or for RBG1)
 N1CHSZ
 180028H
 bit 8
 For NBG1
 N2CHSZ
 18002AH
 bit 0
 For NBG2
 N3CHSZ
 18002AH
 bit 4
 For NBG3
 R0CHSZ
 18002AH
 bit 8
 For RBG0

 xxCHSZ
 character pattern size
 0
 1 cell horizontal x 1 cell vertical
 1
 2 cells horizontally x 2 cells vertically
[Note] xx in the bit name is N0, N1, N2, N3, or R0.

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★ HARDWARE Manual VDP2 User's Manual ★ Chapter 4 Scroll screen
Copyright SEGA ENTERPRISES, LTD., 1997