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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

●Rotation parameter read control register

The rotation parameter read control register specifies whether to read Xst, Yst, and KAst for each line. This is a 16-bit write-only register located at address 1800B2H. The value is cleared to 0 after power-on or reset, so be sure to set it.

RPRCTL 1800B2H
   15   
   14   
   13   
   12   
   11   
   10   
   09   
   08   
 -
 -
 -
 -
 -
 RBKASTRE
 RBYSTRE
 RBXSTRE

   07   
   06   
   05   
   04   
   03   
   02   
   01   
   00   
 -
 -
 -
 -
 -
 RAKASTRE
 RAYSTRE
 RAXSTRE

　

Parameter read enable bit : Parameter read enable bit
(RAXSTRE, RBXSTRE, RAYSTRE, RBYSTRE, RAKASTRE, RBKASTRE)
Coefficient table start address KAst, screen screen start coordinates Xst, Yst
Specifies whether to read from the rotation parameter table at that line.

RAXSTRE 1800B2H bit 0 For Xst of rotation parameter A
RBXSTRE 1800B2H bit 8 For Xst of rotation parameter B
RAYSTRE 1800B2H bit 1 For Yst of rotation parameter A
RBYSTRE 1800B2H bit 9 For Yst of rotation parameter B
RAKASTRE 1800B2H bit 2 For KAst with rotation parameter A
RBKASTRE 1800B2H bit 10 For KAst of rotation parameter B

RxSTRE process
0 Do not read the specified parameter on that line
1 Read the specified parameters at that line
[Note] x in the bit name can be AX, BX, AY, BY, AKA, or BKA.

When this bit is set to 1, the specified parameter will also be read when the next rotation parameter is read, and this bit will be cleared to 0 at the same time. Therefore, if you want to read parameters for each line, set this bit to 1 for each line.

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