Intel has published an interface specification that will allow OEMs to design legacy I/O circuitry while driving the transition from ISA bus-based systems to the PCI bus, as required by PC 98.
Intended for both notebook and desktop PCs, the Low Pin Count (LPC) interface allows legacy I/O motherboard components to migrate from the ISA bus to the LPC (local procedure call) interface, while retaining full software compatibility, Intel explained. This will allow manufacturers to reduce overall design costs and facilitate the industry's move toward higher performance, next-generation I/O technologies, such as Universal Serial Bus (USB) and IEEE 1394, or FireWire.
Devices that can connect to the LPC interface include Super I/O, which integrates floppy disk, serial port, parallel port, infrared, and keyboard controllers, according to the LPC interface specification. National Semiconductor Corporation already has introduced a Super I/O chip, the PC87360, which will sample before the end of 1997 as the first in a series of LPC-based Super I/O devices, according to the company. Device features include fewer pins, lower cost, lower power usage, system management, and design flexibility.
"We collaborated with Intel to quickly define and develop the PC87360 in accordance with the new LPC interface specification," said Michael Maia, director of National Semiconductor's Personal Systems group. "This effort will result in a reduced pin count Super I/O solution that addresses the concerns of customers who want more functionality and board space savings."
The LPC specification also addresses motherboard-based sound circuitry, including chips that comply with Intel's Audio Codec '97 standard. Generic memory and system management controllers are the other classes of devices that can be connected to the LPC interface.
The LPC specification allows for a three-phase legacy migration. First, on-board ISA bus legacy I/O peripherals, such as floppy disk controller, parallel port, and keyboard controller, will move to the LPC interface, while non-legacy functions, such as modems, are in transition to USB. The next phase will be the removal of ISA slots, thereby migrating expansion to larger-bandwidth PCI slots inside the box and USB and FireWire outside the box. ISA slots may become optional during this phase of the transition. The final phase removes legacy serial and parallel ports as native USB and FireWire peripherals become ubiquitous.
"As the industry moves toward more powerful, higher-bandwidth solutions, it becomes a burden to carry the older, legacy technologies because of the higher pin counts that require more space, cost, and testing procedures," said Jan Camps, marketing manager for Intel's Platform Component division. "Through our R&D efforts, we have found a way to facilitate this migration, which will result in lower costs and improved efficiency for hardware OEMs and developers, and make the benefits of higher-performing technologies available more quickly for PC users. Intel has opened the specification so the industry can quickly adopt the technology and integrate it into motherboard legacy I/O peripheral development."
Unlike ISA, which runs at 8MHz, LPC will use the PCI 33MHz clock and will be compatible with more advanced silicon processes. Mobile users also will benefit from the reduced pin count because it uses less space and power, and is more efficient thermally.
Info: www.intel.com www.national.com