Chapter
6:
Graphics 215
Character
Memory
DefInitions
of
Multicolored Characters
The
dot
patterns of multicolor characters are stored in character
memory in the same order as a high-resolution character, but each row
(byte) of the pattern looks like this.
Screen Dot 3 2 1 0
~,-"'-.
Character Memory Bits I
76
I
54
I
32
I
10
I
Each
dot
of a multicolor character
is
represented by two bits in charac-
ter memory, rather than one. There are four possible combinations ofthose
two bits (00,
01,
10,
and
11),
giving four possible colors. The colors selected
by those combinations are
as
follows:
Bit Pair Color
Seleded
00
Background color
01
Character color
10
Border color
II
Auxiliary color .
Auxiliary
Color
The auxiliary color
is
stored in the VIC chip. It can be set with a POKE,
but
it uses only four
ofthe
bits in its location (the
otherfour
are used by the
VIC chip's sound generator).
To
set the auxiliary color, you must use bit
masking to preserve the other bits.
1121£1
POKE
36978,
(PEEK(36878)
AND
15)
OR
(16!11AUX)
The auxiliary color can be any of the
16
colors allowed for the back-
ground. Refer to Appendix E for the POKE values for the various colors.
When the VIC
is
powered on, the auxiliary color
is
set
to
0 (black). The
auxiliary color, like the background and border colors,
is
the same for the
entire screen.
By
using the auxiliary color, you can add one
of
the eight
colors not available in high-resolution characters.
To Next Page
Loading...
