Address Decoding

4.1CSR Address Decoding

The 21555 implements a set of CSRs that are mapped in memory or in I/O space. The registers are mapped independently on the primary and secondary interfaces. The following BARs are used for CSR mapping:

•The primary CSR and:

—Downstream Memory 0 BAR is for mapping in primary bus memory address space. The Lower 4KB of this range used to map the 21555 CSRs.

—I/O BAR is for mapping in primary bus I/O space.

•The secondary CSR:

—Memory BAR is for mapping in secondary bus memory address space.

—I/O BAR is for mapping in secondary bus I/O space.

The primary BARs are located in the 21555 primary bus configuration space, and the secondary BARs are located in the 21555 secondary bus configuration space. The memory BARs request 4 KB each (minimum size for Primary CSR and Downstream Memory 0 BAR), and the I/O BARs request 256 bytes each.

4.2Expansion ROM Address Mapping (Decoding)

The 21555 implements one BAR, the Primary Expansion Read Only Memory (ROM) BAR, to map the expansion ROM that can be attached to the 21555. The Expansion ROM can be mapped into primary bus address space only, and is not accessible through a BAR from the secondary bus. The size of the Primary Expansion ROM BAR is programmable through the Primary Expansion ROM Setup register in device-specific configuration space. The size may vary from 4 KB to 16 MB by powers of 2. The Primary Expansion ROM BAR can also be disabled through theSetup register so that it does not request space when the expansion ROM is not implemented.

4.3Memory 0 Transaction Address Decoding

The BARs can be enabled to decode and forward memory transactions to the opposite interface. The 21555 implements primary interface and secondary interface BARs:

•The downstream BARs are in primary configuration space. The BARs decode transactions on the primary bus to be forwarded to the secondary bus.

—Primary CSR and Downstream Memory 0.

—For addresses above the low 4 KB in this address range.

—Upstream I/O or Memory 0.

—Upstream Memory 1.

—Upstream Memory 2.

•The upstream BARs are in secondary configuration space. The BARs decode transactions on the secondary bus to be forwarded to the primary bus.

—Downstream I/O or Memory 1.

—Downstream Memory 2.

—Downstream Memory 3.

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

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Intel 21555 user manual CSR Address Decoding, Expansion ROM Address Mapping Decoding, Memory 0 Transaction 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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