Motherboard Layout and Routing Guidelines

Notice that the timing equations include an extra term to account for the delay due to routing of the BCLK trace on the processor substrate from the processor edge fingers and the processor core. Adding the BCLK adjustment to the timing calculations between processor and chipset guarantees host clock synchronization between the AGPset and processor core. The minimum and maximum values for this term are contained in Table 2-9.

Component timings for the Intel® Pentium® II processor and Intel® 440GX AGPset are contained in Table 2-10. The timing specifications are contained in the Intel® Pentium® II processor and Intel® 440GX AGPset Datasheets. These timing are for reference only.

Table 2-9. Intel® Pentium® II Processor and Intel® 440GX AGPset 100 MHz Timing Specifications

Timing Term

Intel® Pentium® II Processor

Intel® 440GX AGPset

 

 

 

Tco,max [ns]

4.66

4.45

Tco,min [ns]

0.71

0.80

Tsu [ns]

1.97

3.00

Th [ns]

1.61

-0.10

Tclk,min [ns]

0.77

Not applicable

Tclk,max [ns]

0.84

No applicable

Recommended values for system timings are contained in Table 2-10. Skew and jitter values for the clock generator device come from the CK97 clock driver specification. The PCB skew spec is based on the results of extensive simulations at Intel. The Tadj value is based on Intel’s experience with systems that use the Intel® Pentium® Pro processor and Intel® Pentium® II processor.

Table 2-10. Recommended 100 MHz System Timing Parameters

Timing Term

Value

 

 

Tskew,CLK [ns]

0.18

Tskew,PCB [ns]

0.15

Tjit [ns]

0.25

Tadj [ns]

0.40

The flight time requirements that result from using the component timing specifications and recommended system timings are summarized in Table 2-11. All component values should be verified against the current specifications before proceeding with analysis.

Table 2-11. Recommended 100 MHz System Flight Time Specs

Driver

Receiver

Tflight,min

Tflight,max

Intel® Pentium®II processor

AGPset

0.36

2.13

AGPset

Intel® Pentium®II

0.37

1.76

processor

 

 

 

 

 

 

 

Intel® Pentium®II processor

Intel® Pentium®II

1.23

2.39

 

processor

 

 

 

 

 

 

2-18

Intel®440GX AGPset Design Guide

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Intel 440GX Recommended 100 MHz System Timing Parameters, Recommended 100 MHz System Flight Time Specs, Timing Term Value
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440GX specifications

The Intel 440GX chipset was launched in 1997 as part of Intel's series of chipsets known as the 440 family, and it served as a critical component for various Pentium II and Pentium III-based motherboard architectures. Specifically designed for the second generation of Intel’s processors, the 440GX delivered enhanced performance and supported a range of important technologies that defined PC architectures of its time.

One of the main features of the Intel 440GX was its support for a 100 MHz front-side bus (FSB), which significantly improved data transfer rates between the CPU and the memory subsystem. This advancement allowed the 440GX to accommodate both the original Pentium II processors as well as the later Pentium III chips, providing compatibility and flexibility for system builders and consumers alike.

The 440GX chipset included an integrated AGP (Accelerated Graphics Port) controller, which supported AGP 2x speeds. This enabled high-performance graphics cards to be utilized effectively, delivering many enhanced graphics capabilities for gaming and multimedia applications. The AGP interface was crucial at the time as it offered a dedicated pathway for graphics data, increasing bandwidth compared to traditional PCI slots.

In terms of memory support, the 440GX could address up to 512 MB of SDRAM, allowing systems built with this chipset to run comfortably with sufficient memory for the era’s demanding applications. The memory controller was capable of supporting both single and double-sided DIMMs, which provided versatility in memory configuration for system builders.

Another notable feature of the Intel 440GX was its support for multi-processor configurations through its Dual Processors support feature. This allowed enterprise and workstation computers to leverage the performance advantages of multiple CPUs, making the chipset suitable for business and professional environments where multitasking and high-performance computing were essential.

On the connectivity front, the chipset supported up to six PCI slots, enhancing peripheral device integration and expansion capabilities. It also included integrated IDE controllers, facilitating connections for hard drives and CD-ROM devices.

Overall, the Intel 440GX chipset represented a balanced combination of performance, flexibility, and technology advancements for its time. Its introduction helped establish a foundation for subsequent advancements in PC technology and set the stage for more powerful computing systems in the years to come.
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