Manuals / HP / Computer Equipment / Desktops

HP dc7800 tower manual System Resources, Interrupts, Apic Mode

Models: dc7800 tower

1 120
Download 120 pages 24.6 Kb
Page 43
Image 43

System Support

4.3 System Resources

This section describes the availability and basic control of major subsystems, otherwise known as resource allocation or simply “system resources.” System resources are provided on a priority basis through hardware interrupts and DMA requests and grants.

4.3.1 Interrupts

The microprocessor uses two types of hardware interrupts; maskable and nonmaskable. A maskable interrupt can be enabled or disabled within the microprocessor by the use of the STI and CLI instructions. A nonmaskable interrupt cannot be masked off within the microprocessor, but may be inhibited by legacy hardware or software means external to the microprocessor.

The maskable interrupt is a hardware-generated signal used by peripheral functions within the system to get the attention of the microprocessor. Peripheral functions produce a unique INTA-H (PCI) or IRQ0-15 (ISA) signal that is routed to interrupt processing logic that asserts the interrupt (INTR-) input to the microprocessor. The microprocessor halts execution to determine the source of the interrupt and then services the peripheral as appropriate.

Most IRQs are routed through the I/O controller of the super I/O component, which provides the serializing function. A serialized interrupt stream is then routed to the ICH component.

Interrupts may be processed in one of two modes (selectable through the F10 Setup utility):

■8259 mode

■APIC mode

These modes are described in the following subsections.

8259 Mode

The 8259 mode handles interrupts IRQ0-IRQ15 in the legacy (AT-system) method using

8259-equivalent logic. If more than one interrupt is pending, the highest priority (lowest number) is processed first.

APIC Mode

The Advanced Programmable Interrupt Controller (APIC) mode provides enhanced interrupt processing with the following advantages:

■Eliminates the processor's interrupt acknowledge cycle by using a separate (APIC) bus

■Programmable interrupt priority

■Additional interrupts (total of 24)

The APIC mode accommodates eight PCI interrupt signals (PIRQA-..PIRQH-) for use by PCI devices. The PCI interrupts are evenly distributed to minimize latency and wired as shown in Table 4-5.

 

Technical Reference Guide

www.hp.com

4-7

Page 42 Page 44
Page 43
Image 43
HP dc7800 tower manual System Resources, Interrupts, Apic Mode
Page 42 Page 44

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.