Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus interface architecture
Reexamination Certificate
1999-05-10
2003-09-30
Lefkowitz, Sumati (Department: 2181)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus interface architecture
C710S305000, C710S022000
Reexamination Certificate
active
06629186
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of digital systems. More specifically, the present invention relates to the bus controllers of peripheral buses, including their associated device drivers.
2. Background Information
With the advances in microprocessor technology, today's personal computers possess computing power that rivals the capabilities of mainframe computers of past years. The advances had also led to increasing number of electronic appliances, such as set-top box, and other entertainment systems. Increasingly, these computers and electronic appliances are used for multi-media applications, involving isochronous data, such as audio and video. Together, these isochronous data impose a large aggregate bandwidth requirement on the peripheral bus, to which the isochronous peripheral devices are attached. Examples of isochronous devices include cameras, speakers, microphones, scanners, and so forth.
A number of peripheral bus technologies are known in the art. Universal Serial Bus (USB) is an hierarchical serial bus technology developed in recent years to provide a low cost and easy-to-use solution to meet multi-media application bandwidth requirement. To achieve the low cost and easy-to-use objectives, USB supports only a “full speed” signaling rate of 12 Mb/s and a “low speed” signaling rate of 1.5 Mb/s. To accommodate the “low speed” devices on the peripheral bus, speed shifting is performed on a packet boundary basis when alternating between the “full speed” and the “low speed” devices. Experience has shown that this is a significant performance burden to the “full speed” devices, and a waste of bandwidth. Moreover, recent experience has further shown that even greater bandwidth is required to support the ever increasing number and varieties of isochronous peripheral devices users are interested in.
Another popular peripheral bus technology is the Firewire or IEEE 1394 serial bus technology (IEEE 1394, High Performance Serial Bus, 1995). 1394 supports multiple signaling rates, up to 400 Mb/s. While the aggregate bandwidth is substantially higher than USB, 1394 is fundamentally a more costly technology. Moreover, it too employs the above mentioned wasteful speed shifting approach to accommodate the slower speed devices.
Thus, an improved approach to provide the desired increase in bandwidth, yet backward compatible to some of the lower cost solutions, such as USB, and unencumbered by the disadvantages of the prior art, is desired.
SUMMARY OF THE INVENTION
A novel bus controller including its device drivers are disclosed. The device drivers include a number of programming instructions. Upon programmed with the programming instructions, a digital system is enabled to operate the bus controller to provide a number of request packets destined for a bus agent to a hub, in an integrated multi-packet form, in bulk, and at a first communication speed, for the hub to buffer and forward the request packets to the bus agent, on a packet-by-packet basis, at a second communication speed.
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Garney John I.
Howard John S.
Iyer Venkat
Blakely , Sokoloff, Taylor & Zafman LLP
Intel Corporation
Lefkowitz Sumati
Vo Tim
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