ACT apricot - Text Mode

CRT CONTROL
detailed below. Since words are accessed from the RAM, the
LSB is held permanently at the low state by a hardwired
connection. The 4 MSB are also always low since the areas
to be accessed are within the bottom 64K of the system
memory map.
address bit 19 15 4
a
10 a a alp p p p p p p p p p plr r r r 01
I I I~
ll-bi t Pointer I
Raster Address
Text Mode
In the text mode, each character for display is stored in 32
contiguous bytes in memory, organised as 16 consecutive
16-bit words, defined as a font cell. An example of a font cell
is detailed below. This represents the character A (of the
default font) as illustrated on Figure 2.
1020H
I
WORD
ADDRESS
1030H
16-bit WORD
DO D15
a a a 00 0 a a a a a a 0 a a a
o a a a a a a a a a a
o 0 a a a 000 a a
a
0000000
a 0000000
a 0000000
a 0000000
o a 0 a a 0 x a - strikethrough
a a a a a 0 a a bi t
a
0000000
o 0000000
a a a a a a a a a 0 a a
a a a a a a a a
0 a a a a a a a
a a a
0 a a a a 0 a a a a 000
a a a 0 a a 0 a 0 a a 0 a 0 0 x - underline
a a a a a a 0 a a a a a a 0 a a bit
I I I I
I
Display bits Non-display