Sharp MZ-80B Owner's Manual page 54

47
Input and output of the V-RAM for graphic display can be controlled as follows by means of the
data delivered to OUT port $F4.
Output data
V-RAM GRPH I V-RAM GRPH IT
to port $F4
Input Output Input
00 0 X
X
01 X
X 0
02 0 0
X
03
X
0
0
oc
0 X X
OD X
X 0
OE 0 0
X
OF
X 0 0
Note Input 0: V-RAM transfer enabled
X : V-RAM transfer disabled
Output
0:
shown on CRT display
X : not shown on CRT display
Output
X
X
X
X
0
0
0
0
If 03H is delivered to port $F4 with OlH stored in $EOOO, then OlH is transferred to V-RAM G-ll
$EOOO but is not displayed on the CRT because the display indicator is set at V -RAM G-1.