Technical Reference

2.7 PCI Conventional Interrupt Routing Map

This section describes interrupt sharing and how the interrupt signals are connected between the PCI Conventional bus connectors and onboard PCI Conventional devices. The PCI Conventional specification describes how interrupts can be shared between devices attached to the PCI Conventional bus. In most cases, the small amount of latency added by interrupt sharing does not affect the operation or throughput of the devices. In some special cases where maximum performance is needed from a device, a PCI Conventional device should not share an interrupt with other PCI Conventional devices. Use the following information to avoid sharing an interrupt with a PCI Conventional add-in card.

PCI Conventional devices are categorized as follows to specify their interrupt grouping:

•INTA: By default, all add-in cards that require only one interrupt are in this category. For almost all cards that require more than one interrupt, the first interrupt on the card is also classified as INTA.

•INTB: Generally, the second interrupt on add-in cards that require two or more interrupts is classified as INTB. (This is not an absolute requirement.)

•INTC and INTD: Generally, a third interrupt on add-in cards is classified as INTC and a fourth interrupt is classified as INTD.

The ICH6-R has eight Programmable Interrupt Request (PIRQ) input signals. All PCI Conventional interrupt sources either onboard or from a PCI Conventional add-in card connect to one of these PIRQ signals. Some PCI Conventional interrupt sources are electrically tied together on the board and therefore share the same interrupt. Table 16 shows an example of how the PIRQ signals are routed.

For example, using Table 16 as a reference, assume an add-in card using INTA is plugged into PCI Conventional bus connector 3. In PCI bus connector 3, INTA is connected to PIRQB, which is already connected to the ICH6-R audio controller. The add-in card in PCI Conventional bus connector 3 now shares an interrupt with the onboard interrupt source.

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Intel D925XBC, D925XCV specifications PCI Conventional Interrupt Routing Map
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D925XBC, D925XCV specifications

The Intel D925XBC and D925XCV are motherboards designed for Intel's LGA 775 socket, targeted primarily at the desktop market during the mid-2000s. These motherboards support Intel's innovative 800 MHz Front Side Bus and provide a robust platform for various computing applications, including gaming and multitasking.

One of the standout features of the D925XBC and D925XCV is their compatibility with Intel's Pentium 4 and Pentium D dual-core processors. These processors deliver impressive performance, especially for users engaging in demanding tasks such as video editing and 3D rendering. The support for dual-channel DDR2 memory allows for increased bandwidth and improved overall system performance, accommodating up to 8 GB of memory in total.

The motherboards are equipped with the Intel 925X chipset, which integrates advanced technologies. This chipset supports Intel's Enhanced Memory 64 Technology (EM64T), allowing for more efficient processing power and better resource management. The presence of the I/O Controller Hub (ICH6) also enhances connectivity options, including SATA 3.0 Gbps interfaces for faster data transfer rates and improved storage capabilities.

Regarding expansion and connectivity, both motherboards feature multiple PCI Express slots along with PCI slots, allowing users to customize their systems according to their needs. This expandability is essential for gamers and professionals looking to add advanced graphics cards and other peripherals. Additionally, these boards come with integrated audio, ensuring satisfactory sound quality without the need for additional sound cards.

The D925XBC and D925XCV motherboards also include integrated Ethernet controllers, supporting fast network connectivity essential for gaming and high-speed internet access. With multiple USB ports available, users can connect a wide variety of devices easily, enhancing the flexibility of their setups.

In terms of form factor, both boards follow the ATX layout, providing compatibility with a broad range of computer cases. This ensures ease of installation and upgrades while promoting good airflow and optimal thermal management for the components installed.

Overall, the Intel D925XBC and D925XCV motherboards integrate essential features and technologies that provide a solid foundation for desktop computing during their time. With strong processing capabilities, expandability, and good connectivity options, these boards were well-received by users looking for reliable performance and versatility in their systems.
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