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★ HARDWARE Manual ★ VDP2 User's Manual ★ Chapter 6 Rotating scroll screen
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VDP2 User's Manual/Chapter 6 Rotating scroll screen

●Coefficient table control register

The coefficient table control register controls the coefficient table. This is a 16-bit write-only register located at address 1800B4H. The value is cleared to 0 after power-on or reset, so be sure to set it.

KTCTL 1800B4H
   15   
   14   
   13   
   12   
   11   
   10   
   09   
   08   
 -
 -
 -
 RBKLCE
 RBKMD1
 RBKMD0
 RBKDBS
 RBKTE

   07   
   06   
   05   
   04   
   03   
   02   
   01   
   00   
 -
 -
 -
 RAKLCE
 RAKMD1
 RAKMD0
 RAKDBS
 RAKTE

　　
Coefficient line color enable bit (RAKLCE, RBKLCE)
Specify whether to use line color screen data in coefficient data.

RAKLCE 1800B4H bit 4 For rotation parameter A
RBKLCE 1800B4H bit 12 For rotation parameter B

This bit is valid only when the corresponding coefficient table is used and the data size is 2 words.

RxKLCE process
0 Do not use line color screen data in coefficient data
1 Use line color screen data in coefficient data
[Note] A or B is entered for x in the bit name.

　　
Coefficient data mode bit : Coefficient mode bit (RAKMD1, RAKMD0, RBKMD1, RBKMD0)
Specify what parameter the coefficient data will be used as.

RAKMD1,RAKMD0 1800B4H bit 3,2 For rotation parameter A
RBKMD1,RBKMD0 1800B4H bit 11,10 For rotation parameter B

This bit is always valid, so be careful when rewriting it.

RxKMD1 RxKMD0 mode Function of coefficient data
0 0 0 Use as scaling factor kx, ky
0 1 1 Use as scaling factor kx
1 0 2 Use as scaling factor ky
1 1 3 Use as viewpoint coordinates Xp after rotation transformation
[Note] A or B is entered for x in the bit name.

　　

Coefficient data size bit (RAKDBS, RBKDBS)
Specify the size of coefficient data.

RAKDBS 1800B4H bit 1 For rotation parameter A
RBKDBS 1800B4H bit 9 For rotation parameter B

This bit is only valid when the corresponding coefficient table is used.

RxKDBS Coefficient data size
0 2 words
1 1 word
[Note] A or B is entered for x in the bit name.

　　
Coefficient table enable bit : Coefficient table enable bit (RAKTE, RBKTE)
Specifies whether to use a coefficient table.

RAKTE 1800B4H bit 0 For rotation parameter A
RBKTE 1800B4H bit 8 For rotation parameter B

RxKTE process
0 Do not use coefficient table
1 Use coefficient table
[Note] A or B is entered for x in the bit name.

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★ HARDWARE Manual VDP2 User's Manual ★ Chapter 6 Rotating scroll screen
Copyright SEGA ENTERPRISES, LTD., 1997