Product Reference
2–79
Serial Port
Use SETUP to independently enable or disable either of the two onboard serial ports. When SETUP
is used to enable or disable a port, the change does not take effect until the system is rebooted.
The I/O addresses and interrupt assignments ( IRQ s) fo r the serial p or ts cann ot be chan ged . Table
2–54 lists the I/O addresses and IRQs of each port. These resources are freed for use by other
peripherals installed on the PC/104 bus when their respective ports are disabled.
Table 2–54. Serial Port Resources

Port Address

Serial 1 3F8h – 3FFh
Serial 2 2F8h – 2FFh
Serial 3 3E8h – 3EFh
Serial 4 2E8h – 2EFh
The BIOS normally logs Serial 1 and Serial 2 as COM 1 and CO M2. COM1 an d CO M2 are logic al
designations, not physical values. When the system boots, the BIOS scans the standard serial port
addresses and installs the first port i t find s a s CO M1. If it f ind s a seco nd p ort, i t ins talls th at one
as COM2, and so on. If you disable a serial port, the d e signatio ns o f all hig her- numbere d CO M
ports changes. See the Serial Port section of this Chapter for more information.
Parallel Port
The Little Board/486e parallel port SETUP allows it to be e nable d as th e pr imary or seco ndary
port. The I/O ports and interrupt request channels are freed for use by other peripherals installed
on the PC/104 bus when the parallel port is disabled. Table 2–55 summarizes the resources that
can be used for the parallel port.
Table 2–55. Parallel Port Resources

Selection I/O Address Interrupt

Primary 0378h - 037Fh IRQ7
Secondary 0278h - 027Fh IRQ5
Disable None None
The BIOS normally logs the primary and secondary par allel ports as LP T1 and L PT2. L PT1 and
LPT2 are logical designations, not physical values. When the system boots, the BIOS scans the
standard parallel port addresses and installs the first port it finds as LPT1. If it finds a second
port, it installs that one as LPT2, and so on. If a parallel port i s disable d, the design ation of all
higher-numbered LPT ports change.
For further information about utilizing the parallel po rt, see th e se ction o n the bi- direct ional
Parallel Port.