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MZ3500
4-10. Character VRAM select circuit
The signal BLNK is used to address the ASCII RAM
within address area of 0000-07FF in transferring
the display data from the VRAM to the CG.
Lov
0
*/ when
300^07FF
6 1 1 6( 2 K * 8 )
ASCB
CS
V-RAM
* 0 0 0 0
- 0 7 P F
2 1 1 4 ( ! K x 4 )
First half of
attribute
2 1 1 4 ( 1 K * 4 )
Latter half of
attribute
* 0 0 0 0
- 0 3 F F
# 0 4 0 0
- 0 7 F F
#0000
-07FF
BL'SC
BLNK Erase signal
H-SYNC
TT_
TTJ
Period that the GDC is enabled to read/write
and draw graphic data.
BLANK
[Circuit description]
With respect to GCD1, the assignment during read/write
of the character VIDEO-ROM is per the table below. The
character VRAM select circuit is provided. Jo accomplish
this function.
6 I 1 6 > 2 K » 8 )
ASL C
V - K A M
Latter half of
attribute
First half
of attribute
t
ARIO = H1
T
AK10
= Low
*07FF
*0400
#03KF
toooo
8bil
- 47 -
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