Service manual
c)
Example
of
CPU
read/write
access
• Shown next are access
examples
of
REPLACE
write,
PS
ET
write,
and SEARCH read in
the
320 x 200,
16-color
mode.
As
for
display
colors, Plane I
corresponds
to
8,
IT
to
R,
ill
to
G,
and
IV
to
I.
MZ-800
CD
REPLACE
write
• To
develop
light
yellow
characters on the graphic
screen.
Plane I
(B)
data
Plane
11
(R)
data
V
Bo
1
0
1 ° 1'1'1'1'
i
COTo
i '1' 1
°R~
R
Display before
write
A
M
Plane
III
(G) data
It develops the screen
when
a next
CG
patterns are
written after setting
the
REPLACE
mode
and
the
light
yellow
color
in
the
WF register.
Mode
BlA Calor
designation
WF
register
~-O--o=r!]
, ,
--oJ:
Light
yellow
replace
mode
Plane I
So, the
bit
"1"
of
the
write
data becomes the color
specified
by
WF and rest
of
others become
RESET
(black).
°
Write
data I
(CG
pattern) , °
~-----
Plane
11
°
V
I ° 1
°lolol~liEJ
10t'lol'[0]
, ! °
I'
I
R
A
M
Plane
III
Plane IV
Display after
write
1 ° I , 1 °
I'
I ° 1
' 1
°
liJ
1 °
I'
1
° 1
' 1 °
I'
1
ON
®
PSET
write
• To overlay a
light
yellow
hatching
over
the
graphic
display screen
of
CD.
Mode
BlA Calor
designation
WF
register
'--1_,
___
0---'1_0----'-1_,
_____
0_1
:
Light
yellow
PSET
mode
G R B
Write
data
~
°
°
I (B)
11
(RI
°
1 ° 1 ° 1 °
I'
1 ° 1
' 1 ° I I ° 1
'
I'
I'
1 °
I'
I'
I, 1
V
R
A
Display after
write
M
1 °
I'
I'
So,
only
the
bit
"1"
of
the
write
data becomes
the
color specified
by
WF in
this
mode,
and rest
of
other
colors
do
not
change.
@
SEARCH
read +
PS
ET
write
• To change
light
yellow
in ® above
to
change
to
red
• The
following
data are set
when
the
memory
is read
after setting
the
light
yellow
search
mode
in
the
RF
register.
Mode
BlA Calor
designation
RF
register
LI_,_IL-_----'-I_o_--'-I_,
____
o---'I
:
Light
yellow
search
III
(GI
IV(!)
I'
24
I'
I'
1 °
I'
1 °
I'
1 ° 1
' 1
°
I'
1 0
I'
1
Read data 1 ° ° °
0'
I:
Only
the
bit
of
light
yellow
L.-
__________
--'
becomes
",",
•
When
the
above
read data are read after setting the
red PSET
mode
in
the
WR register.
...
" I
~
'"
~
1
~
1
<J
"
co
"
'"
Cl) 0
Cl)
'"
Cl)
en
a:1=
a:
'"
a:
i~
'"
u a: t
::;;
j
Now,
a partial
color
change has been attained.
As in
above,
it
enhances fast
display
change
with
less
of
VRAM accessing
by
using
various
write
modes.