Yamaha V9938 Programmer's Manual page 10

L
Layout
A map of patterns or sprites which identify where to display specific object or which object
should be displayed in specific position. In case of patterns (font), Pattern generator Table
identifies the appearance of font, but in order to display these patterns in specific position,
programmer should put its number into Pattern Layout Table in respective location
O
Object
Font patterns or a sprite.
P
Pattern
A property of an object identifying how object looks like. Object can be a font pattern or a
sprite pattern. Pattern may be represented by one byte or 8 bytes in different modes; its
contents codes colors of the pixels displayed. For some modes, 8 bits (one byte) can code
8 pixels – 0 for background color and 1 for foreground color, in other modes 8 bits can
code 4 pixels – with colors 0, 1, 2, and 3. To display font patterns on the screen it may not
pattern layout
be enough to set its , but also put its pattern number into the map. VDP,
when displaying the picture, reads the number of pattern to display, and then refers to its
actual image to font pattern generator table
Port
Is a physical latch with specific system address for CPU reads and writes to communicate
with VDP. VDP has four ports, port #0 is a read/write data port, port #1 is write register
set-up port, port #2 is write palette port, and port #3 is write register data port
R
Register
Register is a static place within VDP for control information about VDP's mode, screen
property etc. Registers can be Status, Video or Command. They can be accessed directly
or indirectly. Access to the registers is made through consecutive writes to specific VDP
ports
, thus in order not to break the order and thus successful completion of specific
operation, programmer should disable interrupts.
RGB
Abbreviation for base colors Red, Green and Blue. It may be used to describe hardware
wiring with three analog signals; or to describe a color composition for the pixel. Note that
when coding RGB in VDP palette registers programmer uses 3 bits for every base color,
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