System Support

Link Layer

The link layer provides data integrity by adding a sequence information prefix and a CRC suffix to the packet created by the transaction layer. Flow-control methods ensure that a packet will only be transferred if the receiving device is ready to accomodate it. A corrupted packet will be automatically re-sent.

Physical Layer

The PCI Express bus uses a point-to-point, high-speed TX/RX serial lane topology. One or more full-duplex lanes transfer data serially, and the design allows for scalability depending on end-point capabilities. Each lane consists of two differential pairs of signal paths; one for transmit, one for receive (Figure 4-1).

System Board

Device A

TX

RX

PCI Express Card

Device B

Figure 4-1. PCI Express Bus Lane

Each byte is transferred using 8b/10b encoding. which embeds the clock signal with the data. Operating at a 2.5 Gigabit transfer rate, a single lane can provide a data flow of 200 MBps. The bandwidth is increased if additional lanes are available for use. During the initialization process, two PCI Express devices will negotiate for the number of lanes available and the speed the link can operate at. In a x1 (single lane) interface, all data bytes are transferred serially over the lane. In a multi-lane interface, data bytes are distributed across the lanes using a multiplex scheme.

4.2.3 Option ROM Mapping

During POST, the PCI bus is scanned for devices that contain their own specific firmware in ROM. Such option ROM data, if detected, is loaded into system memory's DOS compatibility area (refer to the system memory map shown in chapter 3).

4.2.4 PCI Interrupts

Eight interrupt signals (INTA- thru INTH-) are available for use by PCI devices. These signals may be generated by on-board PCI devices or by devices installed in the PCI slots. For more information on interrupts including PCI interrupt mapping refer to the “System Resources” section 4.3.

4.2.5 PCI Power Management Support

This system complies with the PCI Power Management Interface Specification (rev 1.0). The PCI Power Management Enable (PME-) signal is supported by the chipset and allows compliant PCI peripherals to initiate the power management routine.

 

4-4

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Technical Reference Guide

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HP dc7800 tower manual Option ROM Mapping, PCI Interrupts, PCI Power Management Support, Link Layer, Physical Layer
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dc7800 tower specifications

The HP dc7800 Tower is a powerful desktop computer designed for professional and enterprise environments. Known for its stability, performance, and versatility, this model has secured its place in a variety of business settings. Launched in the mid-2000s, it embodies HP’s commitment to quality and innovation.

One of the main features of the HP dc7800 is its form factor. The tower configuration allows for easy upgrades and maintenance, providing ample space for additional hard drives, memory, and other components. This level of accessibility makes it ideal for businesses that need to adapt their systems to changing requirements.

The dc7800 is powered by Intel's Core 2 Duo processors, offering dual-core technology that enhances multitasking capabilities. With clock speeds ranging from 1.8 GHz to 3.0 GHz, this system can handle demanding applications with relative ease. It also supports Intel's vPro technology, which allows for remote management and security features, making it an excellent choice for organizations prioritizing IT control.

Another notable characteristic is the support for up to 8GB of DDR2 RAM. This allows for efficient data processing and improved performance when running multiple applications simultaneously. Additionally, the dc7800 features multiple storage options, accommodating both SATA hard drives and solid-state drives, which can significantly enhance boot times and overall system responsiveness.

Connectivity options on the HP dc7800 are robust. It includes a variety of USB ports, audio jacks, and optional legacy ports, ensuring compatibility with a wide range of peripherals and accessories. Networking capabilities are also prominent, with built-in Gigabit Ethernet providing high-speed internet access.

Furthermore, the desktop tower is designed with energy efficiency in mind. It meets ENERGY STAR certification standards, which not only helps reduce operational costs but also minimizes environmental impact.

Overall, the HP dc7800 Tower embodies a blend of performance, expandability, and energy efficiency, making it a reliable choice for businesses in need of a robust desktop solution. With its legacy of dependability and its suite of modern technologies, it continues to serve as a valuable asset in enterprise environments.
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