Canon AS-100C, Field Service Manual

Page: 18 / 136

For a half-tone chromatic display, two chromatic signals of a
primary color and a semi color are required but no combination
is available between a primary and a semi color of same color
type.
Therefore, a display with 27 different colors is possible as shown
in Fig. 1.2.6.
— Sequence of color combination
27 combinations of 3 colors are
possible as indicated by the solid
line.
Referring to Fig. 1.2.5, eight different patterns are.selected in
advance on the pallets; therefore, eight colors be selected
differently from the 27 colors.
Option in DISPLAY CONT
VRAM .... Optional chip of 32 KB x 1 for B/W display
1.2.A KEYBOARD
I/O CONT KEY BOARD
KEY
INPUT
CLOCK
-DAT^
-RESi
ROM(1KB)
Key dataRAM(64B)
CPU
80A1
Key matrix
KDO
/i-------
vKey code
Pointing device
(optional)
O H CM
m
Fig. 1.2.7 Block diagram of the keyboard
1-12