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M./ 3500
48. CG Address Select Circuit
Rasters, o
411'Rasters. l
k
n \
8 KM ASC n CG
Mask ROM
AI2
When 400 rasters in use
A 3 o;
When 200 Raster
in use
Goes high per
400 rasier
I.S166
Parallel to Serial
Converter
JCL
When 200 rasters on ASCII in use
(only the high order 8 bytes of 16 bytes are set to Iow level.)
ASCII C.G. Structure
* 11- K F
1020
101 K
16 Bytes
ifiBytes
1000
OK F F
0020
001 F
8 Bytes
0018
0017
8 Bytes
(»i i n
(Kid l
8 Bytes
«Bytes
= ,
Character
Code "01 "
For
Model 3500
Character
Code
"00"
For
Model 3500
= = = = =
Code
"01"
For
Model 3200
</,-
'////
////////
'' Code "01"
'
', For
?
;, Model 3500:
Character
Code
"00"
For
Model 3200
/ Character '/
' Code "00" <
>, For
<
;,,Model 3500^
t
A I 2 = I
A 12 = 0
t
1
A 3 = l
t
A 3=0
t
AB« 1
\
A3 - U
8 x 1 6 dot
Pattern
400 Rasters
8 x 8 D o t
Pattern
200 Rasters
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 codes used by
the 200-raster video display unit of the YX-3500 and by the 400-raster
video display unit of the YX-3500. The CG address select Circuit 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 Iow level
which sets A12 of the CG to Iow level continuously, so that the CG
address 0000-OFFF is selected. Also, gate (2) is opened so that the
CPU.
8 bits
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