Intel 281809-003 manual Ide Support, Floppy Controller, Keyboard Interface

IDE SUPPORT

The Advanced/RH motherboard provides two independent high performance bus-mastering PCI IDE interfaces capable of supporting PIO Mode 3 and Mode 4 devices. The system BIOS supports Cylinder Sector Head (CHS), Logical Block Addressing (LBA) and Extended Cylinder Sector Head (ECHS) translation modes as well as ATAPI (e.g. CD-ROM) devices on both IDE interfaces. IDE device transfer rate and translation mode capability can be automatically determined by the system BIOS.

Normally, programmed I/O operations require a substantial amount of CPU bandwidth. In multi-tasking operating systems like Microsoft Windows 95, the CPU bandwidth freed up by using bus mastering IDE can be used to complete other tasks while disk transfers are occurring. A driver is required for the IDE interface to operate as a PCI bus master capable of supporting PIO Mode 4 devices with transfer rates up to 22 MB/sec while minimizing the system demands upon the processor.

Detailed information on the PCIset is available in the Intel 82430HX PCIset data sheet.

NATIONAL SEMICONDUCTOR PC87306B SUPER I/O CONTROLLER

Control for the integrated serial ports, parallel port, floppy drive, RTC and keyboard controller is incorporated into a single component, the National Semiconductor PC87306B. This component provides:

∙Two NS16C550-compatible UARTs with send/receive 16 byte FIFO

— Support for an IrDA compliant Infra Red interface

∙Multi-mode bi-directional parallel port

— Standard mode; IBM † and Centronics† compatible

—Enhanced Parallel Port (EPP) with BIOS/Driver support

—High Speed mode; Extended Capabilities Port (ECP) compatible

∙Industry standard floppy controller with 16 byte data FIFO (2.88 MB floppy support)

∙Integrated Real Time Clock accurate within +/- 13 minutes/yr at 25º C and 5 volts when the system is continuously powered on

∙Integrated 8042 compatible keyboard controller

The PC87306B is normally configured by the BIOS automatically. However configuration of these interfaces is possible via the CMOS Setup program that can be invoked during boot-up. The serial ports can be enabled as COM1, COM2, IrDA, or disabled. The parallel port can be configured as normal, extended, EPP/ECP, or disabled. The floppy interface can be configured for 360 KB or 1.2 MB 5¼” media or for 720 KB, 1.2 MB, 1.44 MB, or 2.88 MB 3½” media. Header pins located near the back of the board allow cabling to use these interfaces

FLOPPY CONTROLLER

The PC87306B is software compatible with the DP8473 and 82077 floppy disk controllers. The floppy interface can be configured for 360 KB or 1.2 MB 5¼” media or for 720 KB, 1.2 MB, 1.44 MB, or 2.88 MB 3½” media in the BIOS setup. By default, the Floppy A interface is configured for 1.44 MB and Floppy B is disabled. Another setup option prevents the user from being able to write to floppy. Configuring the floppy interface for 1.2 MB 3 ½” (3-mode floppy) requires the use of a driver to operate correctly.

KEYBOARD INTERFACE

PS/2 keyboard/mouse connectors are located on the back panel side of the motherboard. The 5V lines to these connectors are protected with a PolySwitch† circuit which acts much like a self-healing fuse, re-establishing the connection after an over-current condition is removed. While this device eliminates the possibility of having to replace a fuse, care should be taken to turn off the system power before installing or removing a keyboard or mouse. The system BIOS can detect and correct keyboards and mice plugged into the wrong PS/2† style connector.

Advanced/RH Technical Product Specification ∙ Page 11