Chapter 15. How to use VDP2

■15.1 Operation flow

An example procedure for defining and configuring VDP2 data is outlined below.

Step 1.

Set the TV screen mode.

• Selection of normal graphics, high resolution graphics, and dedicated monitor
• Setting interlaced mode
• Setting vertical resolution and horizontal resolution

Step 2.

Select the scroll screen 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 for each screen.

• Select cell format or bitmap format.

(1) When in cell format

• Number of character colors
• character size
• Pattern name data size
• plane size
• Scaling function
• Line scroll function
• Vertical cell scrolling function
• Mosaic processing function

(2) When in bitmap format

• bitmap color count
• bitmap size
• Scaling function
• Rotation function
• Mosaic processing function

Step 4.

Select 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.

Select to use VRAM.

• VRAM bank division
• VRAM access method

Step 8.

Create character patterns and pattern name tables.

• Select character number assistance mode.
• Sets the invert function bit.
  When using bitmap format, creates a bitmap pattern.

Step 9.

Create other VRAM tables.

Step 10.

Define priority and color operations considering 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.

Reconfigure the screen, redefine and reconfigure VRAM and registers, taking the story into account.