Commodore 128 System Manual page 392

The Screen Map is POKEd with a Screen Display Code value
(see Appendix D). For example:
POKE 1024, 13
will display the letter M in the upper-left corner of the screen.
5 5 2 9 6
-
55336
55376
5 5 4 16
55456
55496
55536
55576
55616
55656
55696
55736
55776
55816
55856
55896
55936
55976
56016
56056
56096
5 6 136
56176
56216
56256
If the color map is POKEd with a color value; this changes the
character color. For example:
POKE 55296, 1
will change the letter M inserted above from light green to white.
F-2
COLOR MEMORY MAP
1-*-
COLUMN
20
55335
I
10 -
t
56295