Z80 Datasheet, PDF (226/330 Pages) Zilog, Inc. – Z80 CPU PERIPHERALS

< %27 2GTKRJGTCNU
7UGT /CPWCN

Set Interrupt Control
Enable AND/
Int.
OR
High Masks
Low Follows
0
1
11
Used in
Mode 3 Only
If the mask follows bit is high, the next control word written to the port
must be the mask:
MB7 MB6 MB5 MB4 MB3 MB2 MB1 MB0
In addition, the interrupt enable flip-flop of a port may be set or reset
without modifying the remainder of the interrupt control word. This is
accomplished by issuing the following command:
Enable
Int.
X
X
X
00
11
UM008101-0601
Parallel Input/Output