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(2) 640 x. 400 bits display mode
fH = 20.92 kHz
fV = 47.3 Hz
4-4
: Y -. l : l
Doi Clock (ÖD)
2 X C C L K
Horizontal display time
HFP
HS
H BP
Vertical display time
VFP
VP
VBP
GDC-1 (80 digits)
Character display (40 digits)
(19.66MHz)
(9.83 MHz)
(4.9152MHz)
<2.4575MHz>
32.55^s 80 Chr. /40 Chr.
4.88ps
4^is
6.5^s
19.16ms
0.527ms
0.24 ms
1.198ms
GDC-2
8 bils
19.66MHz (50.86ns)
4.9152MHZ (203.45ns)
«-
-
*~
(tREF=0.6ms)
«-
-
~
*•
-
graphic)
16 bits
9.83MHZ (101.92ns)
2.4575MHz (406.9ns)
-
-
5 Chr.
(tREF = 1.23ms)
-
-
-
-
-
Total rasters: 441 rasters
Display rasters: 400 rasters
(3) CRT synchronizing signal specification
(400 raster
CRT)
1. Horizontal synchronization frequency (fH): 20.92kHz
2. Vercial synchronization frequency ( f V ) : 47.3Hz
3. Total rasters: 441 rasters
4. Rasters used: 400 rasters
5. Display dots: 640 x 400 dots
6. Dot Clock: (19.66MHz)
7. Timing
Video
( Positive;"
9. HS, VS, and VIDEO Signals are supplied from the LS
type TTL IC (totem pole)
6) Setup of GCD master/slave
(1) Master/slave setup by combination
^"^^^^
Character
^\^
GDC
Graphic
^^^^^
GDC
^\^
Without VRAM PWB
8 bit structure
48K byte
200 rasters
16-bit structure
96 K byte
48K byte
400 rasters
40 digits
Character
Character
Character
80 digits
Character
Character
Graphic
Master should be setup in the above mai.iv,v.
Vid«-o
i-os 11 iv,. r
-•" 0.5ms.---
19 IC
!
VFP: 11 rasters (0.5ms)
VS:
5 rasters (0.24ms)
VBP: 25 rasters (1.2ms)
8. Output method: HS, VS. and VIDEO are indpendent
Outputs.
(2) I/O signal switching
(8255, PB7 )
n ft / 1 r
»
( C S P - 2 )
i/ c YVC 1 ^
VSYNC
Switching
Circuit
<
» Y *- ' Y "" C°
- 34 -
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