<75/86>VDP2 User's Manual/15.2 How to use RAM

★ HARDWARE Manual ★ VDP2 User's Manual ★ Chapter 15 How to use VDP2

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VDP2 User's Manual/Chapter 15 How to use VDP2

■15.2 How to use RAM

When using VDP2, define and set data in VRAM, color RAM, and registers.

●VRAM

The data defined in VRAM varies depending on the scroll screen used, screen format, screen size, and image processing function used. Define each data in VRAM according to the register settings, and set the defined address in each address register. Table 15.1 shows the data defined in VRAM and the related main registers.

Table 15.1 Data defined in VRAM and related registers

data What to define Related registers Data to set pattern name table character pattern starting address of pattern name control register (Text/Reference) ・Pattern name data size ・ Character number assistance mode ・ Pattern name auxiliary data Plane size register (Text/Reference) ・Plain size when displaying in cell format Normal scroll screen map register (Text/Reference) ・Start address of pattern name table placed on each plane Rotating scroll screen map register (Text/Reference) ・Start address of pattern name table placed on each plane map offset register (Text/Reference) ・3-bit map offset value added to the upper part of the map register character pattern cell dot data character control register (Text/Reference) ・Number of character colors, character size bitmap pattern bitmap pattern Data of character control register (Text/Reference) ・Number of character colors (number of bitmap colors) ・ bitmap size ・ bitmap enable map offset register (Text/Reference) ・Address of bitmap pattern boundary line scroll table horizontal and vertical screen scroll value, horizontal coordinate increment line scroll table address register (Text/Reference) ・Start address of line scroll table Line & vertical cell scroll control register (Text/Reference) ・Scroll function control data vertical cell scroll table Vertical screen scroll value Vertical cell scroll table address register (Text/Reference) ・Start address of vertical cell scroll table Line & vertical cell scroll control register (Text/Reference) ・Scroll function control data Rotation parameter table rotation parameters, Related registers of coefficient table RAM control register (Text/Reference) - Purpose of using VRAM on rotating scroll screen Rotation parameter table address register (Text/Reference) ・Start address of parameter table Rotation parameter mode register (Text/Reference) ・Specification of rotation parameter mode coefficient table Coefficient table data (scaling coefficient kx, ky, Starting point coordinates Xp after rotation transformation) RAM control register (Text/Reference) - Purpose of using VRAM on rotating scroll screen Coefficient table control register (Text/Reference) ・Coefficient data mode ・ Data size of coefficient data ・ Coefficient table enable Coefficient table address offset register (Text/Reference) ・Start address offset value of coefficient table line color screen table color ram address line color screen table address register (Text/Reference) ・Color mode of line color screen ・ Start address of line color screen table back screen table RGB color data Back screen table address register (Text/Reference) ・Back screen color mode ・ Back screen table start address line window table horizontal starting point coordinates, Horizontal end point coordinates line window table ad response register (Text/Reference) ・Line window enable ・ Start address of line window table

●Definition of color RAM

data	What to define	Related registers	Data to set
pattern name table	character pattern starting address of	pattern name control register (Text/Reference)	・Pattern name data size ・ Character number assistance mode ・ Pattern name auxiliary data
Plane size register (Text/Reference)	・Plain size when displaying in cell format
Normal scroll screen map register (Text/Reference)	・Start address of pattern name table placed on each plane
Rotating scroll screen map register (Text/Reference)	・Start address of pattern name table placed on each plane
map offset register (Text/Reference)	・3-bit map offset value added to the upper part of the map register
character pattern	cell dot data	character control register (Text/Reference)	・Number of character colors, character size
bitmap pattern	bitmap pattern Data of	character control register (Text/Reference)	・Number of character colors (number of bitmap colors) ・ bitmap size ・ bitmap enable
map offset register (Text/Reference)	・Address of bitmap pattern boundary
line scroll table	horizontal and vertical screen scroll value, horizontal coordinate increment	line scroll table address register (Text/Reference)	・Start address of line scroll table
Line & vertical cell scroll control register (Text/Reference)	・Scroll function control data
vertical cell scroll table	Vertical screen scroll value	Vertical cell scroll table address register (Text/Reference)	・Start address of vertical cell scroll table
Line & vertical cell scroll control register (Text/Reference)	・Scroll function control data
Rotation parameter table	rotation parameters, Related registers of coefficient table	RAM control register (Text/Reference)	- Purpose of using VRAM on rotating scroll screen
Rotation parameter table address register (Text/Reference)	・Start address of parameter table
Rotation parameter mode register (Text/Reference)	・Specification of rotation parameter mode
coefficient table	Coefficient table data (scaling coefficient kx, ky, Starting point coordinates Xp after rotation transformation)	RAM control register (Text/Reference)	- Purpose of using VRAM on rotating scroll screen
Coefficient table control register (Text/Reference)	・Coefficient data mode ・ Data size of coefficient data ・ Coefficient table enable
Coefficient table address offset register (Text/Reference)	・Start address offset value of coefficient table
line color screen table	color ram address	line color screen table address register (Text/Reference)	・Color mode of line color screen ・ Start address of line color screen table
back screen table	RGB color data	Back screen table address register (Text/Reference)	・Back screen color mode ・ Back screen table start address
line window table	horizontal starting point coordinates, Horizontal end point coordinates	line window table ad response register (Text/Reference)	・Line window enable ・ Start address of line window table

Define color data for palette-style sprites and scroll screens. The color data stored in the color RAM is in RGB format and has three modes. The mode selection is specified by the color RAM mode (CRMD1, CRMD0, bits 13 and 12) of the RAM control register (18000EH).

The most significant bit of the color data stored in the color RAM is the enable bit when the special color calculation mode is mode 3. When the special color calculation mode is mode 3, the color format is palette format, and the color calculation enable bit is 1, color calculation is performed on a dot-by-dot basis using color data whose most significant bit is 1. Masu.

●Color RAM reference

Color RAM is referenced from data in character patterns, bitmap patterns, and line color screen tables. Color RAM addresses are represented by 11 bits. If the number of character colors or bitmap colors is 16, a 7-bit palette number is added to the upper part, making it 11 bits, and if it is 256 colors, a 3-bit palette number is added to the upper part, making it 11 bits. Masu. The palette number of a character pattern is located in the pattern name data and auxiliary data of the pattern name control register, and the palette number of a bitmap pattern is located in the bitmap palette number register.

●Register

Registers are generally 16 bits that are write-only and specify the functionality of VDP2. One function may span several registers, and some functions may be grouped together in one register.
Set the registers that correspond to the functions you want to use as necessary.

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★ HARDWARE Manual ★ VDP2 User's Manual ★ Chapter 15 How to use VDP2