Commodore 128 Programmer's Reference Manual page 233

THE POWER BEHIND COMMODORE 128 GRAPHICS 223
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MACHINE LANGUAGE
There are three ways to select the placement of character memory, as shown in Figure
8-11. Example A places character memory using the shadow register $0A2C in place of
the actual $D018 register. Example B specifies the start of the bit map at $2000 (using
shadow register $0A2D). Example C specifies the start of the C64 bit map or character
memory.
LDA $02AC LDA $02AD LDA $D018
AND #$F0 AND #$F0 AND #$F0
ORA #$Z ORA #$08 ORA #$Z
STA $02AC STA $02AD STA $D018
Figure 8-11. Selected Character Memory Location
In Figure 8-11, Z is a value in the table in Figure 8-9.
STANDARD CHARACTER MODE
HOW TO ENTER STANDARD
CHARACTER MODE
The C128 powers up in standard character mode. This mode displays characters on the
default screen. The character is displayed in a single color on a single color background.
This is the mode in which you write (enter) programs. When you press RUN/STOP and
RESTORE, the G128 defaults to the text screen.
Location 53265 (and its shadow register $00D8) determine whether the C128 is
operating in standard character mode. If'bit 5 is 0, as it is on power-up, the C128 is in
character mode; otherwise it is in bit map mode.
Location 53270 (and its shadow register $00D8) determine whether the characters
are standard (single color) or multi-color. Bit 4 of 53270, and the shadow bit, bit 7 of
$00D8, specify multi-color mode. If these bits are equal to zero, characters are standard;
otherwise they are multi-color. See the Multi-color Character Mode section for more
details on selecting multi-color character mode.