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M Z 3500
2) Read/write from 2-80 to VRAM
(1) Timing period for display and
V-RAM Read/write.
Diplay period
////
Range whers GDC can draw.
Fly-back period
H • SYNC-
BLNK-
(2) Timing that the Z-80 can read/write VRAM
The Z-80 can read/write VRAM when GDC FIFO
buffer is either empty or Füll, and can be accessed by
3) Structure of Character VRAM
(1) When read/write from GDC
#07 FF
#0000
refreshing during the display period. Number
of
characters that can be read/write within one raster in
any mode.
(A)
(B)
(A)
2KX8
A S C I I
8bi t
30
* D i
(B)
2 K X 4
Attribute
4 b i t
)ö
* U
l
1
A S C l K S b i t )
i
i
_ — — — __
— — _ _ i -
l
( 1 2 b i t )
i
DO Dl D2 D3 D4 D5 D6 D7|D
0 D1 D2 D3
L
Blink
Vertical line (R)
Horizontal line (B)
(2) During display
#07FF
#0000
(A)
2 K X 8
(B)
2 K X 4
,
12bi t
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