User`s guide

Operation Theory • 49
4.6.4 I/O Address
The 8254 in the PCI-9111 occupy 4 I/O address as shown below.
BASE + 40 h LSB OR MSB OF COUNTER 0
BASE + 42 h LSB OR MSB OF COUNTER 1
BASE + 44 h LSB OR MSB OF COUNTER 2
BASE + 46 h CONTROL BYTE
The registers BASE+0 to BASE+3 control the programming of the 8254. Users
can refer to the 82C54 data sheet for more details of the 82C54. You can
download the data sheet at the following web site:
“http://support.intel.com/support/controllers/peripheral/231164.htm” or
“http://www.tundra.com/”