Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-02-25
2002-08-13
Kizou, Hassan (Department: 2738)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S419000, C370S429000, C370S463000, C709S249000, C375S222000
Reexamination Certificate
active
06434161
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates to the field of data transmitting and receiving interface devices and methods. More particularly, the present invention relates to a system and method for directly transferring data between a host system, such as a personal computer, and a digital signal processor for performing, among other things, modulation/demodulation.
2. Present State of the Art
With the advances and the ubiquitous nature of computer and telephone communication systems requiring expanded data transfer and processing capabilities, there is a continuing demand for improving the transfer of data from a host system such as a computer system, to a communication network such as a telephone infrastructure, via a communication module. For example, the increased transfer of voice, sound, and image data over networks such as the Internet require high speed data processing capabilities at very high data transfer rates. Such advanced technological requirements place demands on hardware and software components and require efficient processing and transport of data through such interfacing communication modules.
A conventional communication module implementation generally includes a modem (modulator/demodulator) operably coupled with a host system such as a computer. The host system provides the user interface for the generation or consumption (viewing, hearing, or storing) of transfer data by a user of the host system. Prior art configurations have connected host systems with a communication module such as a modem via a serial or parallel port or interface.
A traditional communication module such as a modem may include a standard Universal Asynchronous Receiver/Transmitter (UART) or UART emulator in which the format of data is converted. A UART device essentially converts data between parallel and serial formats depending upon whether the host system is transmitting or receiving data. Data on the host system is stored and operated upon in parallel form and must therefore be converted to serial form for transmission from the host system into the communication network.
FIG. 1
represents a prior art configuration of network interface configuration
100
comprising a host system
102
, a UART
106
, and a modem
120
for interfacing with communication network
128
. Host system
102
is further comprised of a host bus
104
which is traditionally a parallel interface for support devices such as processors, memory, and other peripheral devices such as UART
106
. UART
106
traditionally interfaces with host system
102
via host bus
104
and receives data for transmission in parallel form as represented by transmit path
108
. UART
106
also provides received data to host system
102
in parallel form as represented by receive path
110
. Status and control information (e.g., status regarding whether transmit data has been forwarded or whether pending receive data is awaiting retrieval by host system
102
) are also provided by UART
106
in control registers
118
as represented by control path
112
. Data interfacing outside UART
106
traditionally occurs via a serial port
122
, and in many personal computers, UART
106
is internally housed and presents a serial COM port for interfacing with serial peripherals.
In
FIG. 1
, the primary function of modem
120
is to allow the transmission and reception of data over a telephone medium such as communication network
128
. Modem
120
traditionally comprises a UART
124
and a DSP
126
. UART
124
reconverts transmit data back from serial format to parallel format for processing by DSP
126
. UART
124
also converts receive data from parallel to serial for transferring to UART
106
. DSP
126
provides modulation and demodulation of data for transceiving over channel
130
with communication network
128
. Transceived waveforms comprise analog waveforms which are modulated and demodulated for carrying data over communication network
128
.
Traditional UARTs in a modem device typically process data in block mode and when processing is completed such as transmission of transmit data or receipt and demodulation of receive data, an interrupt is sent to the host system or, alternatively, a status is posted in a control register which may be polled by the host system to signify a request for the transfer of additional data or to inform the host system to retrieve the available data. By way of example, a 1-byte UART would transfer a single byte of data for each interrupt request or status posted and reacted upon. UARTs operate, for example in a transmit mode, by transferring a parallel byte over the host bus to a holding register from which it may be serially transferred. When the holding register becomes empty, a subsequent interrupt invites the host system to transfer an additional byte of data.
Advances in the UART art created a conventional UART having a plurality (i.e., usually
16
) buffers which operate as First In First Out (FIFO) buffers (e.g., transmit buffers
114
, and receive buffers
116
both of
FIG. 1
) providing interim storage of additional bytes of data prior to initiating an interrupt to the host system. Further advances in the prior art resulted in UART emulation wherein UART
106
and modem
120
were effectively combined into a single function and the conversion of parallel data present in UART
106
into serial data for transmission between UART
124
over serial port
122
was discontinued. It should be recognized that if UART
106
and modem
120
are merged, serialization of transferred data becomes unnecessary. Although serialization in a merged architecture is abrogated, the merged configuration must still present a UART-appearance to host system
102
to retain compatibility with existing drivers and control functions pertaining to the transfer of data between host system
102
and communication network
128
.
Conventional UARTs may be adequate for lower data rate transfers of information, however, as transmission data rates increase due to increased bandwidth appetites, piecemeal transfers of data between a host system and a communication module such as a modem become increasingly more burdensome upon host systems that become expected to service interrupt requests nearly incessantly for what have become typical data transfers over communication network
128
. Depending upon the particular software applications being concurrently serviced by the host system, the host system may not have sufficient time to service all of the processing interruptions requested by peripherals.
Additionally, significant latency is introduced in transfers of data between a host system and communication network by any required interim handling of data. As discussed above, traditionally, data passed in parallel form from a host system to holding registers in a UART. These holding registers were then in turn serviced internally by the UART whereupon the data in the registers were serially transferred to another holding register of the modem's UART. The modem's UART needed to retain the data until such data was directly requested by the DSP or until such data may be again transferred to a holding memory accessible by the DSP. Only after the holding registers were serviced by the passing of the data through the stages of the data pipeline, could subsequent data enter the pipeline from the host system. The continuous shuffling of data among intermediate holding registers degradates performance throughput of a communication module because of iterative shifting and relocation of transmit or receive data.
Thus, it is desirable to maximize the data transfer rate between a host system and a communication network via a communication module and further to minimize or control the interruptions to the host system in servicing such data transfers.
SUMMARY AND OBJECTS OF THE INVENTION
It is, therefore, an object of the present invention to provide a data communication module for transceiving data between a host system and a communication network that is capable of directly transferr
Higbee Brent C.
Morrell Garn H.
Poulis Spiro
Wilson Gerald A.
3Com Corporation
Tsegaye Saba
Workman & Nydegger & Seeley
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