Intel 440GX AGPset Clocks, Processor Frequency Select

Design Checklist

3.4Intel® 440GX AGPset Clocks

3.4.1CK100 - 100 MHz Clock Synthesizer

•The system clock which provides 100 MHz to the processor and the Intel® 440GX AGPset, and the clocks for the APIC must be +2.5V.

•If implemented in the clock chip, pin 28, when strapped low, provides a spread spectrum modulation effect which may help reduce EMI. The modulation will be “down spread” only, meaning that the nominal 100/66 MHz frequencies will be modulated 0.25% to 0.5% below 100/66. While this may help EMI testing, performance will be impacted. Check with your clock vendor for availability of this feature.

•SEL pins on CK100 can be used to select special functionality using 8.2K ohm pull-ups to V

Table 3-3. Processor Frequency Select

SEL100/66#	SEL1	SEL0	Function

0	0	0	Tri-state

1	0	0	Test Mode

0	1	1	Active 66MHz

1	1	1	Active 100MHz

•Unused clocks should be terminated to ground with 22 ohm resistors.

•22 ohm series resistors are recommended on the CPU, PCI, and IOAPIC clock outputs.

•In a UP system, clock skew between the 82443GX and the CPU can be reduced by tying the clock driver pins together at the clock chip and driving the CPU and 82443GX from this net with a 10 Ohm resistor at the driver for each.

•10K ohm pull-ups to VCC3.3 are recommended on PCI_STP#, CPU_STP#, PWRDWN#. If POS is not supported, connecting these signals to the PIIX4E is not required. On reset, SUSA# (connected to PWRDWN#) is asserted, which causes the clock outputs to stop. This may cause problems with the ITP when connected. Zero ohm stuffing options can be used to select the functionality.

•Check with your clock vendor and the reference schematics for special layout and decoupling considerations. The reference schematics implement an LC filter on the supply pins to reduce noise.

Intel®440GX AGPset Design Guide

3-8

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 Intel 440GX AGPset Clocks, 1 CK100 100 MHz Clock Synthesizer, Processor Frequency Select

Models: 440GX