10
Real-time Clock, CMOS SRAM, and Battery
The real-time clock is compatible with DS1287 and MC146818 components. The
clock provides a time-of-day clock and a multicentury calendar with alarm features
and century rollover. The real-time clock supports 256 bytes of battery-backed
CMOS SRAM in two banks that are reserved for BIOS use.
The time, date, and CMOS values can be specified in the Setup program. The
CMOS values can be returned to their defaults by using the Setup program.
An external coin-cell battery powers the real-time clock and CMOS memory. When
the computer is not plugged into a wall socket, the battery has an estimated life of
three years. When the computer is plugged in, the 3.3-V standby current from the
power supply extends the life of the battery. The clock is accurate to
±
13
minutes/year at 25 ºC with 3.3 V applied.
Super I/O Controller
The PC87309 Super I/O Controller from National Semiconductor is an ISA Plug and
Play compatible, multifunction I/O device that provides the following features:
•
Serial ports
Two 16450/16550A-software compatible UARTs
Internal send/receive 16-byte FIFO buffer
Four internal 8-bit DMA options for the UART with SIR support (USI)
•
Multimode bidirectional parallel port
Standard mode: IBM and Centronics compatible
Enhanced parallel port (EPP) mode with BIOS and driver support
High-speed extended capabilities port (ECP) mode
•
Floppy disk controller
DP8473 and N82077 compatible
16-byte FIFO
PS/2 diagnostic-register support
High-performance digital data separator (DDS)
PC-AT and PS/2 drive-mode support
•
Keyboard and mouse controller
Industry standard 8042A compatible
General-purpose microcontroller
8-bit internal data bus
By default, the I/O controller interfaces are automatically configured during boot up.
The I/O controller can also be manually configured in the Setup program
.
Serial Ports
Two 9-pin D-Sub serial port connectors, one is located on the back panel and the
other connected to a 10pin header and is relocatable.
