Motherboard Layout and Routing Guidelines

Some of the control signals require pull-up resistors to be installed on the motherboard. AGP signals must be pulled up to VCC3.3 using 8.2K to 10K ohm pull-up resistors (refer to

Section 3.5.1, “82443GX Interface” on page 3-10). Pull-up resistors should be discrete resistors, as resistor packs will need longer stub lengths and may break timing. The stub to these pull-up resistors needs to be controlled. The maximum stub length on a strobe trace is < 0.1 inch. The maximum stub trace length on all other traces is < 0.5 inch.

Note: Under certain layouts, crosstalk and ground bounce can be observed on the AD_STB signals of the AGP interface. Although Intel has not observed system failures due to this issue, we have improved noise margin by enhancing the AGP buffers on the 82443GX. For new designs, additional margin can be obtained by following these AGP layout guidelines.

2.982443GX Memory Subsystem Layout and Routing Guidelines

2.9.1100 MHz 82443GX Memory Array Considerations

Designing a reliable and high performance memory system will be challenging. Careful consideration of motherboard routing and stackup topologies, DIMM topology, impedance, and trace lengths must all be taken into account.

The 82443GX when configured with 4 double-sided DIMMs have heavy DQ loading. To offset the heavy loading on the DQ lines, a FET switch mux is recommended to reduce the loading for memory driving the 82443GX, and vice versa. An alternative NO-FET solution is also provided but this solution has more strict routing restrictions.

Figure 2-16. FET Switch Example

to 82443GX MDs & MECCs

A1

 

 

A2

B1

to DIMM[1:0] DQs

 

B2

to DIMM[3:2] DQs

 

To build large capacity DIMMs (i.e., 512 MB) using present day technology, x4 SDRAM devices must be used. The loading on the control lines (MA/GXx, CS#, DQM, CK, etc.) are now twice the loading of a x8 device. A DIMM which “registers” these control lines must be produced to meet 100 MHz timings (note that a PLL must be added to the registered DIMM and the additional PLL jitter must be factored into the overall timing analysis). Electrical, thermal and layout topologies for these registered DIMMs can be founded at the following Web address:

http://www.intel.com/design/pcisets/memory/index.htm

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Intel®440GX AGPset Design Guide

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Intel 440GX manual 82443GX Memory Subsystem Layout and Routing Guidelines, 1 100 MHz 82443GX Memory Array Considerations
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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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