Sharp MZ-80B Owner's Manual page 132

8.0 PROGRAMMING SUMMARY
8.1 LOAD INTERRUPT VECTOR
8.2 SET MODE
Ml Mo
X X
Ml Mo
Mode
0 0 Output
0 Input
1 0 Bidirectional
I
Bit Control
When selecting Mode 3, the next word must set the I/0 Register :
I/0
1
I
1/0o
1/0
=
1 Sets bit to Input
1/0
=
0 Sets bit to Output
8.3 SET INTERRUPT CONTROL
Int AND/ High/ Mask
0 I
Enable
OR
Low F ollows
Used in Mode 3 only
1 I
If the "mask follows" bit is high , the next control word written to the port must be the mask :
MBo
MB
=
0 , Monitor bit
MB
=
I, 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