Interrupt Controllers; System Timers; Keyboard Controller - Mitsubishi Electric LS Pro Hardware Technical Reference

Memory and I/O Usage

Interrupt controllers

The interrupt controllers are programmed by writing to four 8-bit I/O ports. These are
listed in the following table.
Address
Master controller
0020h
0021h
Slave controller
00A0h
00A1h
Full details on programming 8259 interrupt controllers are given in the manufacturers
data sheet.

System timers

The 8254 compatible system timer is accessed at I/O locations 0040h-0043h. The
following table identifies the function of each port.
Address
0040h
0041h
0042h
0043h
A full description of programming 8254 timers is included in the manufacturers
specification and is not repeated here.

Keyboard controller

The 8042 keyboard controller has two ports which are in I/O space at locations 0060h
and 0064h. The port at 0060h is an output port where keyboard data is made available
to the system. The port at 0064h is the command/status port which is described in
more detail below.
Command/status When the system reads I/O location 0064h it receives information about the status of
port the controller. When the system writes to I/O location 0064h the byte is interpreted
as a command.
5/6 LS PRO HARDWARE TECHNICAL REFERENCE
R/W
R/W
R/W
R/W
R/W
Function
Counter 0 count
Counter 1 count
Counter 2 count
Control register
Function
Port 1
Port 2
Port 1
Port 2