(4)
VDC1 (SP6102-035)
VDC1
functional outline
*
Produces
the DCK (dot clock) by halving 3 master
r clocks
for
400 rasters (CKO), 200 rasters (CK1) and
I ,- superimposing (CK2). The 2XCCK (GDC clock)
is
produced by dividing the above master clocks by 16.
i •
!
Generates
the RASO-RAS5, CAS, and bidirectional
I buffer
gate
signals VDEO-VDE2, which
are
used
by
the
CPU
or GDC
to
access
the
VRAM.
•
Produces
display
timing
control signals.
L
VD~1
!timing control) block diagram
;RESET·
.,
, Vcc
,
~;
GNO
00
01
02
CS
..
•
•
r p r r r r
latm
r---
f-<
0::
0
0-
0
"-
-
"--~
r-
---
CKO
CKl
CK2
42.95MHz
28.64'H,
CLOCK
'r
CLOCK
I----->
SELECT
DIVIDE
r
<:
>
-
I
latch
l
DCK
2xCCLK
CPUA
r
v.
~
t t
WE
DBD
.....
L.....--.
DECODE
MPXER
DECOffi
.
f--
i
TIMING GENERATION
LOAD
OE
RCS
CRL S
/L
READY
RAS
GDE
Fig. 74
-61-
-
MZ-5600
-
-
-
-
-
RASO
RASl
RAS2
RAS3
RAS4
RAS5
VDEO
VDEl
VDE2
CAS
"i5TSP
BLANK
HSYNC
DBIN