Electrical computers and digital processing systems: processing – Byte-word rearranging – bit-field insertion or extraction,...
Reexamination Certificate
2002-09-24
2003-12-16
Coleman, Eric (Department: 2183)
Electrical computers and digital processing systems: processing
Byte-word rearranging, bit-field insertion or extraction,...
C345S520000
Reexamination Certificate
active
06665794
ABSTRACT:
TECHNICAL FIELD
This invention generally relates to data communication for a processing unit in a computer, e.g., a microcomputer.
BACKGROUND
Processing of 3-dimensional graphics and video usually involves transmission and processing of a large amount of graphic data. Consumer multimedia applications such as educational software and computer games, for example, may require processing of a single 3-dimensional image in excess of 20 MB of data. Such data need be transmitted to a graphic controller having a graphic accelerator and a graphic memory from the processor, the system main memory (i.e., RAMs), or another device connected to a communication bus (such as a CD-ROM). Hence, 3D graphics and video demand a large bandwidth for data transmission and a large storage space in the system memory or graphic memory.
One standard communication bus for connecting input and output devices in personal computers is Intel's peripheral component interconnect (“PCI”) bus.
FIG. 1
shows that a PCI chipset
104
is implemented as a communication hub and control for the processor
101
, the main memory
106
, and the PCI bus
110
. The graphic controller
120
is connected as a PCI device and transfers graphic data to a display. Other types of buses can also be connected to the PCI bus
110
through another control chipset. The current PCI bus, limited in bandwidth to 132 MB/s, is often inadequate to support many graphic applications. In addition, since the PCI bus
110
is shared by the graphic controller
120
and other PCI devices
130
, the actual PCI bandwidth available for graphic data is further reduced. Therefore, the PCI bus
110
forms a bottleneck for many graphic applications.
Pre-fetching graphic data to the graphic memory can alleviate the bottleneck of the PCI bus, without increasing the graphic memory (usually at about 2-4 MB). But the performance of the graphic controller may still be limited due to the sharing of the PCI bus. Another approach increases the size of the graphic memory but may not be practical for the mass PC market.
In recognition of the above limitations, Intel developed an accelerated graphic port (“AGP”) designated to transmit graphic data to the graphic controller at a peak bandwidth higher than the maximum bandwidth of the current PCI bus, e.g., up to 1.066 GB/s as supported by the Fast Writes in the latest AGP specification 2.0.
FIG. 2
schematically shows an AGP chipset
210
(e.g., Intel's 440LX AGPset) replacing the PCI chipset
104
in FIG.
1
. The graphic controller
120
is connected through the AGP
220
rather than the PCI bus
110
. The AGP
220
allows the graphic controller
120
to execute data directly from the cache, the main memory
106
, or other PCI devices
130
by reducing or eliminating caching from the graphic memory. Hence, the graphic memory can remain small to reduce cost. In addition, AGP
220
reduces the data load on the PCI bus
110
and frees up the PCI bus
110
for the processor to work with other PCI devices
130
.
It is desirable to further improve the efficiency in transmission and processing of data in personal computers and other systems. In AGP-based computers, for example, transmission of graphic data may be specially designed to fully utilize the high bandwidth of the AGP port.
SUMMARY
The present disclosure provides devices and associated methods for controlling data transfer from a storage device (e.g., a processor cache) to a receiving device (e.g., a graphic processor) in a predetermined ordering. Such predetermined ordering can be used to improve the efficiency of data transmission from the storage device to the receiving device.
One embodiment of the device includes a first circuit to receive data and associated address information from the storage device and a second circuit to reorder the data into ordered packets each in the predetermined ordering. The first circuit is configured to process the address information to determine a data ordering of the received data according to their addresses in the storage device. This data ordering is fed to the second circuit which accordingly performs the reordering operation.
The first and second circuits may be pipelined through a queue circuit to improve the efficiency of the reordering operation. The queue circuit may include a token queue and a data queue that respectively receive and store the tokens and the data from the first circuit.
One of applications of the disclosed devices and methods is to improve the data transfer from a processor to a graphic controller such as AGP-based personal computers.
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Dyer Russell W.
Koker Altug
Coleman Eric
Fish & Richardson P.C.
Intel Corporation
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