Parallel ROM Interface

8

This chapter presents the theory of operation information about the 21555 Parallel ROM (PROM) interface. See Chapter 16 for specific information about the PROM registers.

The 21555 supports the attachment of a standard PROM or EPROM with the addition of a small amount of external logic. Flash ROMs compatible with Intel’s 28F00x can be used with this interface. The 21555 supports a PCI expansion ROM BAR on its primary interface with ROM sizes of 4KB to 16MB. Using these features the 21555 can provide the PCI expansion ROM interface for the subsystem. When the local subsystem does not require a PCI expansion ROM, the expansion ROM BAR can be disabled.

When the host completes the configuration of the primary PCI interface, the PROM may be accessed by the host in the memory address range assigned by the PCI expansion ROM BAR. The PROM is not directly accessible in the memory address space of the secondary PCI interface. However, the PROM can be indirectly accessed from both the primary and secondary PCI interfaces through the 21555 CSRs.

Note: The PROM cannot support simultaneous access using the Table 107, “Primary Expansion ROM BAR” on page 175 and the Table 112, “ROM Control Register” on page 178 at the same time. The results are unpredictable. Additionally, the ROM should not be accessed simultaneously from the primary and secondary interface using the

Table 112, “ROM Control Register” on page 178, otherwise the results are unpredictable.

8.1Interface Signals

The 21555 expansion ROM interface signals are listed in Table 21. The ROM address is driven out on the 8-bit data bus in three consecutive cycles. External octal D registers with active low enables are required to capture the ROM address.

The serial ROM data and clock signals are multiplexed with the ROM signals. A description of the serial ROM interface is given in Chapter 9. The PROM can also be used to interface other slave-only devices to the ROM address and data bus. This configuration is described in Section 8.7.

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

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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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