ACT apricot - Page 91

CRT CONTROL
The strikethrough bit defines the position of the
horizontal line drawn through the character, if the
strikethrough attribute is set for the character in the Screen
RAM. Similarly, the underline bit defines the position of
the line drawn under the character, if the underline
attribute is set.
Graphics Mode
In the graphics mode, each character for display is stored
in 32 contiguous bytes in memory, organised as 16
consecutive 16-bit words, defined as a graphics cell image.
An example of a graphics cell image is detailed below. This
represents the graphics cell N as illustrated on Figure 3.
xxxxH
j
WORD
ADDRESS
j
xxxxH + IOH
I6-bit WORD
DO
DI5
o 0 0 0 0 0 0 0 0 0 0 0 0 000
000 000 0 0 0 0 0 0 0 000
o 0 0 000 0 0 0 0 0 0 0 000
o 0 0 0 0 0 0 0 0 0 0 0 0 000
o 0 0 0 0 0 l1li0 0 0 0 0 0 0 ..
o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
o 0 0 000 0 0 0 0 0 0 0 0 0 0
o 0 0 0 0 0 0 0 0 0 0 0 0 000
o 0 0 0 0 0 l1li0 0 0 0 0 0 0 ..
o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
o 0 0 0 0 0 0 0 0 0 0 0 0 000
o 0 0 0 0 0 0 0 0 000 000 0
o 0 0 0 0 0 l1li0 0 0 0 0 0 0 II
o 0 0 0 0 0 0 0 0 000 000 0
o 0 0 0 0 0 000 0 0 000 0 0