ID/FONT
ROM
Each video
board
has
an
ID/FONT
ROM.
This
is
a 16K-byte wide ROM
that
supplies
the
CPU
with information
about
the
video
board
type. Initialization
and
dot
clock frequency information
is
also provided.
Alpha
character
font is
the
size
and
shape
of
the
dot
matrix
used
to
create
letters, nurnbers,
and
other
keyboard symbols.
The
system Illonitor will display
the
font defined in
the
ID
/FONT
ROM
during
computer
power-up
and
self test.
If
another
font
is
required for
the
application,
the
operating
system
or
application software can specify
another
available font
to
be
used.
Standard
FONT,
or
pixel display
matrix
for
the
video
boards
is shown below:
Medium-Resolution Display:
High-Resolution Display:
Clocks
and
Timing
9 X
12
Character,
10
X
15
Cell
6 X
10
Character,
8 X
16
Cell
The
display clock frequency
is
different for each video board. At power-up,
the
CPU
executes
instructions from
the
Boot
ROM
to
determine
the
presence of
and
type
of
the
video board.
Data
in
the
ID/FONT
ROM
is
placed in a Display Controller register
to
set
the
display clock
frequency.
64
Functional Description
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