H • sync, Blnk, D7 d8----------► dll (a) – Sharp MZ-3500 User Manual
Page 28: 0di d2 d3, A) (b) 2kx8 2kx4
Attention! The text in this document has been recognized automatically. To view the original document, you can use the "Original mode".
M7 3500
2)
Read/write from Z 80 to VRAM
(1) Timing period for display and
V-RAM Read/write.
H • SYNC-
J~L
^>-'7 Range wh°ra RDC can draw.
Fly back perfod
BLNK-
T_
(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 Full, and can be accessed by
refreshing
during
the
display
period.
Number
of
characters that can be read/write within one raster in
any mode.
3) Structure of character VRAM
(1) When read/write from GDC
#07FF
# 0 0 0 0
DO
8bi t
(A)
(B)
2KX8
2KX4
ASC 1 I
Attribute
4 b I t
-D7 D8----------► Dll
(A)
(B)
----------------------------------------------- 1---
1
ASC I K8bit) (
-----------------------------
- —
( I2bil ) )
1
no D1 D2 D3 D4 D5 D6 D7|
d
0
DI D2 D3
■ Blink
Reverse
(G)
. Vertical line IR)
. Horizontal line (B)
(2) During display
#07FF
# 0 0 0 0
(A)
(B)
2KX8
2KX4
12bi t
31