Intel ISP1100 manual IDE Support, Real-Time Clock, Cmos SRAM, and Battery

IDE Support

The server board has two independent bus-mastering IDE interfaces that support:

1.ATAPI devices (such as CD-ROM drives).

2.ATA devices using the transfer modes listed in the Intel ISP1100 Internet Server Technical Product Specification.

The BIOS supports logical block addressing (LBA) and extended cylinder head sector (ECHS) translation modes. The drive reports the transfer rate and translation mode to the BIOS.

The server board supports PCMCIA ATA Type II flash card technology through its IDE interfaces. No special driver is needed for a PCMCIA ATA Type II flash drive since most operating systems see it as standard IDE drive.

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.

A coin-cell Lithium battery powers the real-time clock and CMOS memory. When the computer is not plugged into an AC power source, the battery has an estimated life of three years. When the computer is plugged into an AC power source, 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 25ºC with 3.3 V standby applied.

The time, date, and CMOS values can be specified and the CMOS values can be returned to their defaults in the BIOS Setup program.

NOTE

The recommended method for accessing the date in systems with Intel server boards is indirectly from the real-time clock (RTC) via the BIOS. The BIOS on the server board contains a century checking and maintenance feature that checks the two least significant digits of the year stored in the RTC during each BIOS request (INT 1Ah) to read the date. If the year is less than 80 (when 1980 is the first year supported by the PC), the BIOS updates the century byte to 20 which enables operating systems and applications that use the BIOS date/time services to reliably manipulate the year as a four-digit value.

For more information on a proper date access in systems with Intel server boards, please see: http://support.intel.com/support/year2000/

14 Intel ISP1100 Internet Server Product Guide