SerialExpress cable topologies

Daisy chained I/O attachments

SerialExpress: a user friendly I/O interconnect.

Each SerialExpress cable has a pair of input and output signals, supporting concurrent communications in the A-to-B and B-to-A directions. Data is processed when passing through each of the attached nodes, removing noise in signal values or clock jitter. Signal processing circuits detect unconnected or redundant cable ports, and electronically bypass these unused ports.

Distinct node identifiers are also assigned to each node during a bus reset, so there is no need for the user to set DIP switches.

Packets may be concurrently sent over non-overlapping cable segments, which increases the effective I/O bandwidth by allowing input and output transfers to proceed concurrently.

For short distances, each of the signals is expected to be transmitted over a 150 ohm twisted pair copper wire connection.

Closed-loop I/O attachments

SerialExpress: a robust and efficient I/O interconnect.

With the attachment of an additional cable, the daisy-chained topology becomes a closed-loop topology, with several benefits, as listed below:

Neither Serial Bus nor SCI support duplex closed-loop topologies.

Redundant CPU attachments

SerialExpress: a symmetric multiprocessor interconnect.

With the attachment of an additional processor, redundant multiprocessors can share the I/O devices. As a peer-to-peer interconnect, SerialExpress also allows the CPUs to efficiently communicate with each other.

There are no hierarchical topology restrictions, so any number of CPUs may be attached and the robustness of the interconnect isn't dependent on the functioning of any individual CPU. However, a switch-based interconnect is more efficient when large numbers of CPUs are attached.

Simple I/O communications

SerialExpress: a peer-to-peer I/O interconnect.

Because SerialExpress is a peer-to-peer interconnect, compatible I/O devices (such as a scanner and printer, or a camera and a monitor) can communicate between themselves, without processor intervention. However, simple or general purpose processors are expected to be needed when nonstandard functions (such as frame editing or image enhancement) is required.

Large multiprocessor switches

SerialExpress: a large-scale multiprocessor switch interface.

SerialExpress has the behavior of a split-response bus, in that each transaction consists of two subactions. Each subaction involves the transfer of a request or response subaction between producer and consumer nodes. Since all communications are packet based, these packets can be readily sent through active switch components, when the bandwidth of a single ringlet has been exceeded.

Send mail to dbg@scizzl.com with questions or comments about this web site.
Last modified: May 4, 1997
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SerialExpress has the behavior of a split-response bus, in that each transaction consists of two subactions. Each subaction involves the transfer of a request or response subaction between producer and consumer nodes. Since all communications are packet based, these packets can be readily sent through active switch components, when the bandwidth of a single ringlet has been exceeded.

Send mail to dbg@scizzl.com with questions or comments about this web site.
Last modified: May 4, 1997
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Large multiprocessor switches

SerialExpress: a large-scale multiprocessor switch interface.