Address Decoding

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This chapter presents the theory of operation information about address mapping and decoding. See Chapter 16 for specific information about addressing registers. The following areas are covered:

•Section 4.1, “CSR Address Decoding” on page 34.

•Section 4.2, “Expansion ROM Address Mapping (Decoding)” on page 34.

•Section 4.3, “Memory 0 Transaction Address Decoding” on page 34.

•Section 4.4, “I/O Transaction Address Decoding” on page 42.

•Section 4.5, “Configuration Accesses” on page 44.

The 21555 implements separate Base Address Registers (BARs) on both the primary and secondary interfaces. The BARs denotes address ranges for downstream and upstream forwarding. This addressing is unlike the transparent PCI-to-PCI Bridge (PPB), discussed in Chapter 2, which implements a flat address map encompassing both the primary and secondary interfaces.

The 21555 BARs denote interface ranges for Control and Status Registers (CSR) access.

•Primary Interface – The 21555 responds to those transactions whose addresses fall into one of its primary BAR ranges. All other I/O and memory transactions on the primary bus are ignored by the 21555. The address ranges defined by the primary BARs reside in the primary, or system, address map.

•Secondary Interface – The 21555 responds to those transactions whose addresses reside in one of the secondary BAR ranges. All other transactions on the secondary bus are ignored by the 21555. The address ranges defined by the secondary BARs reside in the secondary, or local, address map.

The system and local address maps are independent of each other. The 21555 supports address translations between the two address maps when forwarding transactions upstream or downstream.

Note: When enabled as a target, the 21555 ignores any transactions that it initiates as a master with the exception of type 0 configuration transactions.

21555 Non-Transparent PCI-to-PCI Bridge User Manual

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Intel 21555 user manual Address Decoding
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21555 specifications

The Intel 21555 is a prominent microprocessor developed by Intel, designed to cater to a variety of computing needs. This processor marks a significant step forward in Intel's lineup and underscores the company's commitment to advancing technology in personal computing, enterprise solutions, and beyond.

One of the standout features of the Intel 21555 is its advanced architecture. It utilizes a multi-core design, enabling improved performance through parallel processing. This architecture allows multiple applications to run seamlessly without a decline in speed. The cores are built on a cutting-edge manufacturing process that enhances energy efficiency while maintaining high clock speeds.

The Intel 21555 supports a wide range of technologies, including Intel Turbo Boost, which enables dynamic adjustments to the processor’s performance based on workload demands. This feature allows the processor to accelerate its speed during intensive tasks, providing users with a responsive experience when it matters the most.

Another key characteristic of the Intel 21555 is its support for integrated graphics. With Intel UHD Graphics technology, users can enjoy enhanced visuals for everyday tasks such as video playback, web browsing, and light gaming. This eliminates the need for a separate graphics card for many users, particularly in home office or light gaming scenarios.

Security is a significant focus in the design of the Intel 21555. It includes built-in hardware-based security features like Intel Trusted Execution Technology and Secure Boot. These features help protect against various types of threats, ensuring that user data remains secure from malicious attacks.

The Intel 21555 is also optimized for use with Intel's platform technologies, including Intel Optane memory and Intel Rapid Storage Technology. These technologies work together to deliver faster boot times and improved system responsiveness, making computing more efficient for users.

Furthermore, the Intel 21555 is designed to support virtualization technologies, allowing multiple operating systems to run concurrently without compromising performance. This is particularly useful for developers and businesses that rely on virtualization for testing and development environments.

In summary, the Intel 21555 is a powerful and versatile processor that reflects Intel's ongoing innovation in the computing space. With its multi-core architecture, enhanced graphics capabilities, strong security features, and advanced technologies, it stands out as an excellent choice for a wide range of applications, serving both casual users and professionals alike.
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