Commodore 128 Programmer's Reference Manual page 121

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COMMODORE 128 GRAPHICS PROGRAMMING 111
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This chapter discusses how to use the Commodore 128 graphics features through
^ BASIC using the VIC (40-column) screen. Except for the sprite commands, each
\ i graphic command is listed in alphabetical order. The sprite commands are covered in
' I Chapter 9. Following the format of each command are example programs that illustrate
the features of that command. Wherever possible, machine language routines are
P[ included to show how the machine language equivalent of a BASIC graphics command
J j operates.
Chapter 8, The Power Behind Commodore 128 Graphics, is a description of the
^ inner workings of the Commodore 128 graphics capabilities. It explains how screen,
j ) color and character memory are used and how these memory components store and
address data in each display mode. Chapter 9 then explains how to use sprites with the
new BASIC commands. Chapter 9 also discusses the inner workings of sprites, their
H storage and addressing requirements, color assignments, and describes how to control
! i sprites through machine language.
p TYPES OF SCREEN DISPLAY
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Your C128 displays information several different ways on the screen; the parameter
"source" in the command pertains to three different modes of screen display.
TEXT DISPLAY
Text display shows only text or characters, such as letters, numbers, special symbols
and the graphics characters on the front faces of most C128 keys. The C128 can display
text in both 40-column and 80-column screen formats. Text display includes standard
character mode, multi-color character mode and extended background color mode.
The Commodore 128 normally operates in standard character mode. When you
first turn on the Commodore 128, you are automatically in standard character mode. In
addition, when you write programs, the C128 is in standard character mode. Standard
character mode displays characters in one of sixteen colors on a background of one of
sixteen colors.
Multi-color character mode gives you more control over color than the standard
graphics modes. Each screen dot, a pixel, within an 8-by-8 character grid can have one
of four colors, compared with the standard mode which has only one of two colors.
Multi-color mode uses two additional background color registers. The three background
color registers and the character color register together give you a choice of four colors
for each dot within an 8-by-8 dot character grid.
Each pixel in multi-color mode is twice as wide as a pixel in standard character
mode and standard bit map mode. As a result, multi-color mode has only half the
horizontal resolution (160 x 200) of the standard graphics modes. However, the
increased control of color more than compensates for the reduced horizontal resolution.
Extended background color mode allows you to control the background color and
foreground color of each character. Extended background color mode uses all four
background color registers. In extended color mode, however, you can only use the first
sixty-four characters of the screen code character set. The second set of sixty-four
characters is the same as the first, but they are displayed in the color assigned to