Mitsubishi Electric Apricot LS Pro, Hardware Technical Reference

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Memory and I/O Usage
Chapter 4
Chapter 6
Appendix A
Appendix C
Pr
eface
Chapter 4Chapter 5
5/6 LS PRO HARDWARE TECHNICAL REFERENCE
Interrupt controllers
The interrupt controllers are programmed by writing to four 8-bit I/O ports. These are
listed in the following table.
Address R/W Function
Master controller
0020h R/W Port 1
0021h R/W Port 2
Slave controller
00A0h R/W Port 1
00A1h R/W Port 2
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 Function
0040h Counter 0 count
0041h Counter 1 count
0042h Counter 2 count
0043h Control register
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.