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M
"
4 8 CG
Address
Select
Circuit
When
200
rasters
on
ASCII
in use
(only
the
high order
8
bytes
of 16
bytes
are set to low
level
I
ASCII C.G. Structure
»
I i r r
1020
10! 1-
leBytes
lOOh
ifiBytes
1000
01-1^
0020
001
t
a
Bytes
0018
0017
K
Bytes
(Hi
in
001 1
8
Bytes
0
Iftk
OKI
fc Bytes
ii i
=^=^
Character
Code
01
For
Model 3500
Character
Code
00
For
Model 3500
==
Code
01
For
Model
3200
'/
'///'
s/
/////^
'
Code
01 ',
' For x
,.
Model
3500:
Character
Code
00
For
Model
3200
/
Character
/i
Code
00 ',
' For <l
^Model
3500^
I
\
l'= I -
M'-O
•>
I
I
A3=l
f
\
1-0
*
1
\
i i
t
M
8x16
dot
>
Pattern
400
Rasters
8x8 Dot
>
Pattern
200
Rasters
i
in
i
ASCII
character
structure
of the 200
raster
CRT
ASCII character structure
of the 400
raster
CRT
[Circuit
description]
(Purpose)
The
character genrerator (CG)
incorporates
all
character
code^
used
by
the
200
raster video
display
unit
of the \X
3500
and by the 400
raster
video
display
unit
of the \X
3500
The CG
address
select
cirruit
is
therefore
used
to
select
those
modes
[Operational
description]
1
When
the 400
raster
CRT is in
use,
RA40
is set to
high
level
which
sets
A12 of the CG to
high
level
at all
times,
so
that
the CG
address
above 1000
is
selected
Also,
gate
(1)
opened
so
that
LC3 is
input
to
A3 of the CG At the
same
time,
gate
(3) is
opened
so
that
the
gate
of the
LS240
is
closed
every
16
bytes
2
When
the 200
raster
CRT is in
use,
RA40
is set
turned
to low
level
which
sets
A12 of the CG to low
level
continuously,
so
that
the CG
address
0000
OFFF
is
selected
Also,
gate
(2) is
opened
so
that
the
CPU
8 b ts
-
45-