<65/86>VDP2 User's Manual/

★ HARDWARE Manual ★ VDP2 User's Manual ★ Chapter 11 Priority Function

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VDP2 User's Manual/Chapter 11 Priority Function

■11.3 Inserting line color screen

The line color screen is a screen that does not have a priority number register, and is forcibly inserted as a second image in the area where the specified screen is the top image, and performs color calculations. At that time, in the part where the line color screen is inserted, the second image before insertion becomes the third image, and the third image becomes the image one level below it (force image). Figure 11.2 shows the insertion of a line color screen.

Figure 11.2 Inserting a line color screen

●Line color screen enable register

The line color screen enable register specifies whether to insert a line color screen when each screen becomes the top image. This is a 16-bit write-only register located at address 1800E8H. The value is cleared to 0 after power-on or reset, so be sure to set it.

LNCLEN 1800E8H

-	-	-	-	-	-	-	-
15	14	13	12	11	10	09	08

07
06
05
04
03
02
01
00

-
-
SPLCEN
R0LCEN
N3LCEN
N2LCEN
N1LCEN
N0LCEN

Line color enable bit : Line color enable bit

07	06	05	04	03	02	01	00
-	-	SPLCEN	R0LCEN	N3LCEN	N2LCEN	N1LCEN	N0LCEN

(N0LCEN, N1LCEN, N2LCEN, N3LCEN, R0LCEN, SPLCEN) Specify whether to insert a line color screen when each screen becomes the top image.

N0LCEN	1800E8H	bit 0	For NBG0 (or for RBG1)
N1LCEN	1800E8H	bit 1	For NBG1 (or for EXBG)
N2LCEN	1800E8H	bit 2	For NBG2
N3LCEN	1800E8H	bit 3	For NBG3
R0LCEN	1800E8H	bit 4	For RBG0
SPLCEN	1800E8H	bit 5	for sprites

xxLCEN	process
0	Do not insert line color screen when compatible screen becomes top image
1	Insert a line color screen when the corresponding screen becomes the top image

[Note] xx in the bit name is N0, N1, N2, N3, R0, or SP.

Line color screens are inserted only in the second image where the screen specified to be inserted becomes the top image.
For sprites, this can only be specified for the entire sprite. If you want to specify it for each character, use the color calculation ratio value for each character.
The blur calculation function cannot be used at the same time.

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★ HARDWARE Manual ★ VDP2 User's Manual ★ Chapter 11 Priority Function