PCI Bus Transactions

5.6Target Terminations

This section describes the following target retries, target disconnects, and target aborts received and returned by the 21555.

Section 5.6.1, “Target Terminations Returned by the 21555” on page 60.

Section 5.6.2, “Transaction Termination Errors on the Target Bus” on page 61.

Section 5.6.2, “Transaction Termination Errors on the Target Bus” on page 61.

5.6.1Target Terminations Returned by the 21555

The 21555 returns a target retry under the following circumstances:

Queue is full for posted memory writes.

Delayed transaction is queued but response is not ready.

Queue is full for delayed transactions. The delayed transaction is not queued.

Serial preload is ongoing.

Primary Lockout Bit is set for primary bus transactions.

Transaction is in progress for CSR generation of I/O or Configuration Access (delayed transaction not ready).

The 21555 is discarding read data.

Target disconnects by the 21555 always consist of STOP# asserted and TRDY# deasserted (that is, a target disconnect without data transfer). The 21555 returns a target disconnect under the following circumstances:

Queue fills during posted write.

Cache line boundary is reached for MWI transaction and the 21555 cannot buffer another cache line.

Cache line boundary is reached for memory write transaction and the Memory Write Disconnect bit is set.

The 21555 runs out of read data during completion of delayed transaction to the initiator.

The 21555 is responding to a nonprefetchable Read transaction if multiple data phases are requested by the initiator.

Multiple data phases requested by the initiator for an I/O or configuration access.

Low two address bits of the transaction are non-zero.

The 21555 returns a target abort and sets the Signaled Target Abort bit in the Primary and Secondary Status register under the following circumstances:

Target abort is detected during a delayed transaction completion on the target bus.

Master abort is detected in response to a delayed transaction on the target bus when the Master Abort Mode bit is set to a 1. See Table 77, “Chip Control 0 Register” on page 156.

Delayed transaction request is discarded after 224 target retries received from the target.

Invalid lookup table entry is encountered when forwarding upstream transactions in Upstream Memory 2 range and the Master Abort Mode bit is set to a 1.

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Intel 21555 user manual Target Terminations Returned by

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.