Editorial Contacts:
Elizabeth Martin
Sr. Communications Specialist
National Semiconductor
408-721-6354

Reader Information:
Harish Nayak
Product Marketing Manager
National Semiconductor
408-721-6429
World Wide Web:
http://www.national.com

High-Performance PCI-to-PCI Bridge
Nile-II functions primarily to allow transactions between a master on one PCI bus and a target on another PCI bus. Nile-II enables system designers to overcome electrical loading limits by creating hierarchical PCI buses.

Nile-II adds value by enabling PCI-based systems like high-end desktops, servers, expansion cards (add-on cards) and docking stations to have many loads and expansion slots for expandability. Particularly important to systems with rich media data streams and MMX applications that require higher bandwidth, Nile-II supports high-speed sustained PCI bursting at up to 120 MB/sec to enhance system performance.

Nile-II supports concurrency on both primary and secondary PCI buses to allow each to operate independently. Thus, the bridge helps isolate bus traffic. This is important as newer generations of desktop systems require more peer-to-peer traffic in the PCI bus, requiring multiple PCI bus segments. Concurrency allows a system to run host-to-disk traffic on the primary bus while peer-to-peer traffic occurs using the graphics adapter and video adapter on the secondary bus. Concurrency enhances performance to promote the ease of use in multimedia-rich systems.

National Semiconductor implements its latest patent pending technology, Speculative Cycle Start, in the Nile-II bridge controller to further enhance performance. Although technology trends are leading towards PCI bursting devices to improve system performance, the majority of PCI devices in the market today do not support PCI bursting. With Speculative Cycle Start, Nile-II saves up to four clock cycles for a single transaction across the PCI-to-PCI bridge, maximizing the performance of PCI cycles for non-bursting PCI devices. Reducing the latency in upstream and downstream transactions provide a substantial bandwidth saving on the PCI bus.

Nile-II Flexibility
Nile-II functions as a transparent or full bridge. In the transparent mode, Nile-II provides a single logical bus with devices on both primary and secondary buses configured by the same Bus 0 configuration cycle. Nile-II in transparent mode is 100% software compatible with previous Nile systems.

In the full bridge mode, Nile-II creates a new independent hierarchical PCI bus and implements the configuration space adhering to the PCI-to-PCI bridge header format. The BIOS fully programs Nile-II registers and the operating system performs bus enumeration. The data buffers are enabled by default and allow concurrent bus operation in both full and transparent bridge modes.

Nile-II supports programmable subtractive or positive decoding for downstream and upstream transactions to allow a flexible system design architecture. Programming in positive decoding mode enhances system performance. In the subtractive decoding mode, Nile-II provides I/O and memory address decode ranges to allow OEMs to program registers with performance critical addresses. For these critical addresses, the performance is almost like a positive decoding agent even if Nile-II is in a subtractive decoding mode.

Innovative Docking With Nile-II
Nile-II incorporates patent-pending SmartDock-II technology to enable true hot-docking, a significantly superior solution to current cold- and warm-docking methods. With true hot-docking, a fully powered portable computer can be inserted into a docking station. Since the portable does not have to be rebooted to activate automatic reconfiguration, true hot docking offers the mobile user immediate access to E-mail, LANs, Modems, etc. without going through a time-consuming reboot, as is common today.

Like the proven first generation Nile (PT80C524), Nile-II continues to provide a transparent PCI-to-PCI mode for current operating systems that do not recognize PCI bus hierarchy. It also supports a full bridge mode for future operating systems which will understand PCI bus hierarchy. Therefore, with Nile-II and future operating systems, additional BIOS will not be required to implement a docking station system design. Either way, adding and upgrading devices in the docking station becomes easier for the end user.

Nile-II offers OEMs a new feature to differentiate their docking strategies by supporting serial and parallel PCI-to-PCI bridge designs. OEMs can design innovative docking mechanisms by implementing the capability to support multiple docking stations in a single system. This capability allows OEMs to offer support for both desktop (A/C powered) and mobile (battery powered) docking stations. A multiple docking station strategy makes it possible for a mobile docking station to be inserted into a desktop docking station, giving additional capacity and flexibility to the user.

The Nile-II register set, in the transparent mode maintains backward compatibility with Nile. Systems originally manufactured with first generation SmartDock Technology will be fully compatible with Nile-II docking solutions. This protects the user investment and provides a smooth upgrade to newer docking station models.

Product Packaging, Availability and Pricing
The PicoPower Nile-II (PT80C525) is available in a single 176-pin very-thin quad flat pack (VQFP). Pricing is $18.00 each in volume quantities. Samples are now available. Volume production will be shipped in the fourth quarter of this year. For more information, please contact Harish Nayak at (408) 721-6429.

The PicoPower brand name and technology was recently acquired by National Semiconductor Corporation from Cirrus Logic, Inc. PicoPower Technology was originally founded in 1991 to design, develop, and market power saving VLSI system controller chips for manufacturers of portables, docking stations, energy efficient desktop systems and embedded computers. With key positions in major world markets, the PicoPowerıs products have secured more than 100 product design wins at top-tier computer manufacturers.

National Semiconductor Corporation® designs, develops and markets semiconductor Technologies For Moving and Shaping Information®. The company focuses on strategic markets within the communications, personal systems, industrial and consumer markets. National Semiconductor is headquartered in Santa Clara, California, and has 20,000 employees worldwide. In fiscal year 1996, the company reported sales of $2.6 billion.

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