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and is intended for exclusive use with graphical-display devices. A.G.P. provides these
performance features:
•
Pipelined-memory read and write operations that hide memory access latency.
•
Demultiplexing of address and data on the bus for near 100 percent bus efficiency.
•
AC timing for 133 MHz data transfer rates, allowing data throughput of 500
MBYTES/sec.
•
A.G.P. complies with the 66 MHz PCI specification.
Universal Serial Bus (USB)
The motherboard has two USB ports; one USB peripheral can be connected to each
port. For more than two USB devices, an external hub can be connected to either port.
The motherboard fully supports the universal host controller interface (UHCI) and uses
UHCI-compatible software drivers. USB features include:
•
Self-identifying peripherals that can be plugged in while the computer is running.
•
Automatic mapping of function to driver and configuration.
•
Supports isonchronous and asynchronous transfer types over the same set of wires.
•
Supports up to 127 physical devices.
•
Guaranteed bandwidth and low latencies appropriate for telephony, audio, and other
applications.
•
Error-handling and fault-recovery mechanisms built into the protocol.
IDE Support
The motherboard has two independent bus-mastering PCI IDE interfaces. These
interfaces support PIO Mode 3, PIO Mode 4, ATAPI devices (e.g., CD-ROM), and Ultra
DMA/33 synchronous- DMA mode transfers. The BIOS supports logical block
addressing (LBA) and extended cylinder head sector (ECHS) translation modes. The
BIOS automatically detects the IDE device transfer rate and translation mode.
Programmed I/O operations usually require a substantial amount of processor
bandwidth. However, in multitasking operating systems, the bandwidth freed by bus
mastering IDE can be devoted to other tasks while disk transfers are occurring.
Real-Time Clock, CMOS RAM 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 realtime 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.