Sharp MZ-80B Owner's Manual page 134

8.0 PROGRAMMING SUMMARY
8.1 LOAD INTERRUPT VECTOR
8.2 SET MODE
Ml Mo
X X
M1 Mo
Mode
0 0 Output
0 Input
1 0 Bidirectional
1 Bit Control
When selecting Mode 3, the next word must set the I/0 Register:
I/0
=
1 Sets bit to Input
I/0
=
0 Sets bit to Output
8.3
SET INTERRUPT CONTROL
Int
AND/
High/ Mask
0
1
Enable OR Low Follows
Used in Mode 3 only
1
0
I/Oo
1
If the "mask follows" bit is high, the next control word written to the port must be the mask:
MB
0
MB
=
0, Monitor bit
MB
=
1, Mask bit from being monitored
125
Also, the interrupt enable flip flop of a port may be set or reset without modifying the rest of the interrupt control
word by using the following command:
I
Int
Enable
X X X 0 0