Topology Definition, Simulation Methodology

Motherboard Layout and Routing Guidelines

Section 2.7, “Timing Analysis” on page 2-17describes the timing analysis for the 100 MHz host bus in more detail. Table 2-4provides recommended flight time specifications for single and dual Intel® Pentium® II processor systems. Flight times are measured at the Intel® Pentium® II processor edge fingers. See the Pentium® II Processor Developer’s Manual

(order number 243502), Chapter 8, “GTL+ Interface Specifications“, for information on GTL+ timing measurements and signal quality specifications.

Table 2-4. Recommended 100 MHz System Flight Time Specs

Driver	Receiver	Tflight,min [ns]	Tflight,max [ns]
Intel®Pentium®II processor	AGPset	0.36	2.13
Intel®440GX AGPset	Intel®Pentium®II processor	0.37	1.76
Intel®Pentium®II processor	Intel®Pentium®II processor	1.23	2.39

2.3.9Topology Definition

GTL+ is sensitive to transmission line stubs, which can result in ringing on the rising edge caused by the high impedance of the output buffer in the high state. GTL+ signals should be connected in a daisy chain, keeping transmission line stubs to the Intel® 440GX AGPset under 1.5 inches. Intel® Pentium® II processors should be placed at the end of the bus to properly terminate the GTL+ signals.

For a single Intel® Pentium® II processor design, Intel recommends that termination resistors be placed at the other (AGPset) end of the bus. This provides the most robust signal integrity characteristics and maximizes the range of trace lengths that will meet the flight time requirements. The recommended termination resistor value is 56Ω ± 5%.

For dual Intel® Pentium® II processor based designs, a termination card must be placed in the unused slot when only one processor is populated. This is necessary to ensure that signal integrity requirements are met. Refer to Slot 1 Bus Termination Card Design Guidelines for details.

2.3.10Pre-Layout Simulation (Sensitivity Analysis)

After an initial timing analysis has been completed, simulations should be performed to determine the bounds on system layout. The layout recommendations in Section 4, “Debug Recommendations” on page 4-1are based on results of pre-layout simulations conducted by Intel.

GTL+ interconnect simulations using transmission line models are recommended to determine signal quality and flight times for proposed layouts. Recommended parameter values can be obtained if your supplier’s specific capabilities are known. The corner values should comprehend the full range of manufacturing variation. Intel® Pentium® II processor models include the I/O buffer models, core package parasitics, and substrate trace length, impedance and velocity. Intel® 440GX AGPset models include the I/O buffers and package traces. Termination resistors should be controlled to within ± 5%.

2.3.11 Simulation Methodology

Pre-layout simulation allows the system “solution space” that meets flight time and signal quality requirements to be understood before any routing is undertaken. Determining the layout restrictions prior to physical design removes iteration cycles between layout and post layout simulation, as shown in Figure 2-13.

Intel®440GX AGPset Design Guide

2-13

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.

Intel 440GX Topology Definition, Pre-Layout Simulation Sensitivity Analysis, Driver Receiver

Models: 440GX