Specifications

Chapter 4: Theory of operation
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onboard battery or the +3.3V power supply voltage can supply power and neither
power source affects the other.
The battery has an expected battery life of 2 years on continuous battery power. In
a system that is powered on much of the time and where the ambient power-off
temperature is less than 60°C, the battery is estimated to have a life of 10 years.
Super I/O
The National PC87309 SuperI/O controller provides a floppy controller, parallel port,
serial port, and a keyboard and mouse controller. It interfaces through the ISA bus
and requires external decoding of the high-orer address bits for full 16-bit decoding
required by PC95/PC97. It uses a 48MHz clock. This design does not use the chip’s
parallel port features.
Floppy disk
The floppy controller device resides inside the Super I/O chip and is accessed at the
standard PC I/O addresses 3F0–3F7h. Floppy interrupts are signaled on IRQ6.
The floppy signals connect to a header on the CPU board allowing ribbon cable
connection of a floppy disk drive. Power is provided to the floppy disk drive via a
jumper that allows user selection of powered or non-powered connection.
COM ports
The Super I/O includes two RS-232 compatible serial ports. The Super I/O chip
includes 16C550 compatible UARTs with separate send and receive 16-byte FIFOs.
• COM 1: Configured at I/O addresses 3F8–3FFh and uses IRQ4, COM 1 signals
pass through a RS232 transceiver IC and out the front panel via an RJ45
connector. This transceiver’s I/O pins meet the electrical portion of the EIA/
TIA-232-E specification as well as EIA/TIA-574-E. COM 1 signals also go out
CompactPCI Backplane connector J3.
• COM 2: Configured at I/O addresses 2F8–2FFh and uses IRQ3, COM 2 signals
pass through a RS232 transceiver IC and out Backplane connector J3. The COM
2 connector can only be accessed by the use of an RTM.
The Super I/O chip allows relocation of these ports to the COM 3 and/or COM 4
standard I/O addresses, respectively. If so configured, COM 3 and COM 4 use I/O
addresses 3E8–3EFh and 2E8–2EFh respectively. If not needed, you can disable these
serial ports in the BIOS setup program’s I/O Device Configuration sub-menu to free
the I/O address and interrupt for usage by other expansion products.
Keyboard and mouse controller
The Super I/O provides an integrated keyboard and mouse controller. The Super I/O
keyboard controller, located at I/O locations 60–64h, is functionally equivalent to
the industry standard 8042A controller.
Do not use both the front and rear connections to COM 1 at the same
time. Only one connection to COM 1 may be used at a time.