Chapter 15 How to use VDP2

■ 15.1 Operation flow

The outline of the procedure example for defining and setting VDP2 data is as follows.

Step 1.

Set the TV screen mode.

• Selection of normal graphic, high resolution graphic, dedicated monitor
• Interlace mode setting
• Vertical resolution and horizontal resolution settings

Step 2.

Select the scroll screen you want to use.

• Normal scroll screen (NBG0, NBG1, NBG2, NBG3)
• Rotating scroll screen (RBG0, RBG1)
• External input screen (EXBG)
• Line color screen (LNCL)
• Back screen (BACK)

Step 3.

Select the function of each screen.

• Select the cell format or bitmap format.

(1) In cell format

• Number of character colors
• Character size
• Pattern name data size
• Plain size
• Scale function
• Line scroll function
• Vertical cell scroll function
• Mosaic processing function

(2) In bitmap format

• Bitmap color count
• Bitmap size
• Scale function
• Rotation function
• Mosaic processing function

Step 4.

Select a color RAM mode.

Step 5.

Select the window you want to use.

• When using a normal line window, store the line window table in VRAM.

Step 6.

Calculate the size of VRAM and the size of the table to be stored in VRAM, and confirm that the table can be stored in VRAM.

• VRAM size
• Character pattern (number and size)
• Pattern name table (number and size)
• Bitmap pattern (number and size)
• Line scroll table
• Vertical cell scroll table
• Rotation parameter table
• Coefficient table
• Line color screen table
• Back screen table
• Line window table

Step 7.

Choose to use VRAM.

• VRAM bank split
• VRAM access method

Step 8.

Create a character pattern and pattern name table.

• Select the character number auxiliary mode.
• Set the inversion function bit.
  For bitmap format, create a bitmap pattern.

Step 9.

Create other VRAM tables.

Step 10.

Define priorities and color operations, taking into account sprite data.

Step 11.

Set special functions.

• Special function code
• Special priority function
• Extended color calculation function
• Blur calculation function
• Color offset function
• Shadow function (normal, MSB)

Step 12.

Redefine and reconfigure VRAM and registers, reconfiguring the screen, taking into account the story.