Viglen VIG556M Manual page 12

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 multi-century 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 (CR 2032) 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.
I/O Interface Controller
The motherboard uses the SMC FDC37C777 I/O controller which features:
• Serial ports:
 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:
 N82077 compatible.
 Single diskette drive interface.
 16-byte FIFO.
 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.
• ISA Plug-and-Play compatible register set.
• PCI PME interface.
• Intelligent auto power management:
 Shadowed write-only registers for ACPI compliance.
 Programmable wake up event interface.
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
One 9-pin D-Sub serial port connector is located on the back panel and is compatible
with NS16C550 UARTs.
V1.0 VIG556M Motherboard Manual
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