<3/86> VDP2 User's Manual / 1.3 Scroll Function

★ HARDWARE Manual ★ VDP2 User's Manual ★ Chapter 1 Functions of VDP2

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VDP2 User's Manual / Chapter

■ 1.3 Scroll function

The scroll function of VDP2 has a scroll screen and a window.

● Display screen

TV screen modes include:

Table 1.1 TV screen mode

TV screen mode	Graphic mode	Horizontal resolution (pixel)	Vertical resolution (pixel)	Display device
normal	Normal graphic A	320	224 240 256 Can be selected from	NTSC method or PAL TV
normal	Normal graphic B	352
High resolution	High resolution graphic A	640
High resolution	High resolution graphic B	704
Dedicated monitor	Dedicated normal graphic A	320	480	31kHz monitor
	Dedicated normal graphic B	352	480	High-definition monitor
	Dedicated high resolution graphic A	640	480	31kHz monitor
	Dedicated high resolution graphic B	704	480	High-definition monitor

The scroll screens that can be displayed are as follows.

Table 1.2 Scroll screen

Scroll screen name		name	remarks
Normal scroll screen	Normal scroll 0	NBG0	Can be moved up / down / left / right and enlarged / reduced
	Normal scroll 1	NBG1
	Normal scroll 2	NBG2	Can be moved up, down, left and right
	Normal scroll 3	NBG3	Can be moved up, down, left and right
Rotating scroll screen	Rotation scroll 0	RBG0	Enlargement / reduction rotation is possible
Rotating scroll screen	Rotating scroll 1	RBG1	Enlargement / reduction rotation is possible
Line screen	Line color screen	LNCL	Used only for color calculations
Line screen	Back screen	BACK	Display only when no other screen is displayed
Extended screen	External input screen	EXBG	Screen input from the outside

The windows are as follows:

Table 1.3 window

Window name	name	remarks
Normal window	W0	Can be a line window
Normal window	W1	Can be a line window
Sprite window	SW	Window with sprite character

● Scroll screen

Each function of the scroll screen is as follows.

Table 1.4 Scroll screen functions

function	Normal scroll screen				Rotating scroll screen
function	NBG0	NBG1	NBG2	NBG3	RBG0	RBG1
Number of character colors	16 colors 256 colors 2048 colors * 32768 colors Choose from 16.77 million colors	16 colors 256 colors 2048 colors * Select from 32768 colors	16 colors Select from 256 colors	16 colors Select from 256 colors	16 colors 256 colors 2048 colors * 32768 colors Choose from 16.77 million colors	16 colors 256 colors 2048 colors * 32768 colors Choose from 16.77 million colors
Character size	Select from 1 horizontal x 1 vertical cell, 2 horizontal x 2 vertical cells
Pattern name data size	Select from 1 word or 2 words
Plain size	Select from 1 horizontal x 1 vertical page, 2 horizontal x 1 vertical page, 2 horizontal x 2 vertical pages
Number of planes	Four	Four	Four	Four	16	16
Bitmap display	It can be displayed	It can be displayed	Cannot be displayed	Cannot be displayed	It can be displayed	Cannot be displayed
Bitmap size	Select from width 512 x height 256 dots width 512 x height 512 dots width 1024 x height 256 dots width 1024 x height 512 dots		none		Width 512 x height 256 dots horizontal 512 x vertical Select from 512 dots	none
Scale function	1/4 to 256 times		none		Possible at any magnification
Rotation function	none				can be
Line scroll function	can be	can be	none	none	none
Vertical cell scroll function	can be	can be	none	none	none
Mosaic processing function	can be				Yes (horizontal only)

[Note] In * , 2048 colors are used when the color RAM mode is mode 1, and mode 0 or 2 is used.
In the case of, it will be 1024 colors.

If you want to display only one rotation scroll screen, you can also display the normal scroll screen at the same time, but if you display two rotation scroll screens, you cannot display the normal scroll screen at all. At this time, the register for setting RBG1 is used for NBG0.
When the external input screen is displayed, NBG1 cannot be displayed. At this time, the register for setting the external input screen is the one for NBG1.

● Line screen

The line color screen is a screen for performing color calculations with other screens. You can make the entire screen a single color or specify a color for each line, but you cannot display characters.
The back screen is the screen that is displayed when all other screens are transparent. You can make the entire screen a single color or specify a color for each line, but you cannot display characters.

● Window

For the normal window, you can select a normal rectangular window that specifies two screen coordinate values at the upper left and lower right, and a normal line window that specifies the left and right screen coordinate values for each line. A sprite window is a window with sprite characters.
Depending on the purpose of use, the window is a "transparency processing window" that specifies the area to be transparent, a "color calculation window" that specifies an area that does not perform color calculation, and a "rotation parameter window" that switches the screen using two rotation parameters. There are three types.
The windows used for each screen and how to overlay them can be specified for each screen.

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★ HARDWARE Manual ★ VDP2 User's Manual ★ Chapter 1 Functions of VDP2