★ 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. A write-only 16-bit register located at address 1800B2H. After turning on the power or resetting, the value will be cleared to 0, so be sure to set it.

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

 07 07
 06 06
 05 05
 04
 03 03
 02 02
 01 01
 00
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 ---
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 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 on 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 of 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 parameter on that line
Note The x in the bit name can be AX, BX, AY, BY, AKA, or BKA.

Setting this bit to 1 also reads the parameter specified when reading the next rotation parameter, and at the same time clears this bit to 0. Therefore, if you want the parameters to be read 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