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With the introduction of the 350- and 400-MHz Pentium® II processors, the PC performance bar has been raised once again. This new processor is not only up to 20% faster than its predecessor, the 333-MHz Pentium II processor with a 66-MHz system bus, but it also boasts a new 100-MHz system bus that can produce up to a 50% increase in system and memory bandwidth. The result is a high-performance platform ideal for today's advanced visual computing, Internet, and E-business applications used by professional desktop, entry-level workstations and servers in business and PC enthusiasts in the home.
Moving to a 100-MHz system bus changes the infrastructure of the whole platform, creating significant challenges for the platform developer to balance platform performance. Not only does the main memory and chip set require leaps in performance, but clock drivers and other support peripherals are necessary, as are thermal, EMI, routing, and other design considerations. The primary challenge is how to deliver this new level of performance in a balanced platform without adding significant new cost drivers.
Intel is making it easier by taking a total system view and enabling the entire 100-MHz platform. As part of its ongoing efforts to work closely with the industry, Intel is providing much more than just faster processors. Let's take a closer look at some key technology enablers Intel is providing to balance the platform and make the transition easier:
- faster memory
- enhancements in chip set design with the introduction of the Intel® 440BX AGPset;
- a complete set of developer design tools.
Faster Memory
In order to ensure 100-MHz main memory was available in volume at platform introduction, Intel worked very closely with the DRAM industry from the beginning. To avoid adding to the cost of memory components, Intel led the development of a specification for 100-MHz SDRAM called the PC 100 memory specification that can be implemented within the existing DRAM manufacturing infrastructure.
100-MHz SDRAM was developed simultaneously with the Intel 440BX AGPset, so that feedback from the memory industry could be integrated into chip set design. This industry cooperation resulted in optimal levels of interoperability and compatibility, including a DIMM specification so that every 100-MHz SDRAM DIMM component, regardless of manufacturer, will look and function the same.
The finishing touch on the PC 100 memory specification was the creation of an external test facility that allows manufacturers to obtain valuable feedback on compliance issues. As a result of this industry-wide design effort, multiple vendors are shipping interoperable and compatible 100-MHz SDRAM components in volume today.
Chip Set Enhancements
To support the increased system bandwidth demands of the 100-MHz bus, the new Intel 440BX AGPset builds on the Quad Port Acceleration (QPA) architecture introduced in 1997 with the Intel® 440LX AGPset. With approximately twice the number of transistors as its predecessor, the Intel 440BX AGPset provides higher levels of concurrency to dramatically improve performance. Enabling this higher system bandwidth requires three essential enhancements in chip set design:
- Enhanced distributed arbitration—distributed arbitration is enhanced between the 350- or 400-MHz Pentium II processor, the AGP graphics processor, the PCI bus, and 100-MHz SDRAM memory enables system performance gains.
- Deeper buffers—builds on the already well-established foundation of Quad Port Acceleration to deliver faster data throughput.
- Improved memory management—increases the number of pages that can be simultaneously opened in memory to 32. This decreases latency by eliminating the overhead of opening and closing pages in a multitasking application environment.
In addition to higher system bandwidth, the Intel 440BX AGPset improves reliability and data integrity. It supports multiple copies of memory control signals for improved reliability, and implements a technique called hardware scrubbing which increases data integrity by allowing the memory controller to automatically correct ECC errors and identify DIMMs that may contain multiple errors.
Intel's new chip set design also offers flexible support for both 66-MHz or 100-MHz designs, allowing developers to cost-effectively provide a choice of performance options for different market segments, using a standardized platform. In addition, the new chip set provides full ACPI support for the Instantly Available PC to communicate when it appears to be off, yet wake up instantly on demand.
Design Tools
Perhaps one of the most important aspects of platform development is how to put it all together, quickly and cost effectively. Intel is helping here too with a complete set of design tools intended to help the platform developer meet his development goals with low-cost, fast time-to-market designs.
Intel used its advanced simulation design methodologies to create a robust set of 100-MHz system design guidelines which address various issues including detailed pin-outs, timing issues and component design considerations. One key area is system interconnect design. See the top story in this issue of Platform Solutions on 100-MHz System Bus Interconnect Design.
These design tools enable the cost-effective implementation of four-layer motherboards in the industry-standard form factors of ATX, NLX and micro-ATX. This creates the ability of 100-MHz platforms to ramp quickly into volume price segments.
Delivering 100-MHz Platforms
Memory specifications, advanced chip set designs and design tools are now in place to enable the fast time-to-market implementation of 100-MHz platforms with 350- and 400-MHz Pentium II processors. This enables the industry to deliver the highest performance available through robust, balanced platforms.
1998 represents a year of transition for the PC platform. The Intel 440BX AGPset offers OEMs with a new level of design flexibility for Pentium II processor-based platforms. Platform suppliers now have the capability to implement 66-MHz or 100-MHz designs using the same set of building blocks. The result is a set of cost-effective design solutions with the power to address the price/performance needs of targeted market segments.
Sunil Kumar is the Chip Set Product Marketing Manager in Intel's Peripheral Components Division. He manages Intel's AGPset products for the Performance Desktop, Workstation and Server market segments.
For More Information:
Intel 440BX AGPset product web site
Intel Chip Sets Product web site
Pentium II processor developer web site
Memory Technology news page in Platform Solutions
AGP Technology news page in Platform Solutions
System Design Technology news page in Platform Solutions
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* Legal Information © 1998 Intel Corporation
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