Abstract:
A system includes a chassis and a slot in the chassis. The slot has a depth dimension along which a removable module may be moved to insert the module in the slot and remove the module from the slot. The system includes waveguides, which have couplers that are arranged at different depths of the slot to couple the waveguides to the module in response to the module being inserted into the slot.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/810,665, which was filed on Jan. 16, 2013, and was a national stage application under 35 U.S.C. §371 of PCT/US1043233, which was filed on Jul. 26, 2010. Each of these applications is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    A computing system may be a modular system. The system may include a processing module and a storage module for example. The modules can be installed in a chassis that provides communication channels and power to the modules. The chassis provides a communications channel between the modules and can also provide the modules with power. The channel between the modules may cause a module to wait before it can send data to another module. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    Some embodiments of the invention are described with respect to the following figures: 
           [0004]      FIG. 1  is a module according to an example embodiment of the invention; 
           [0005]      FIG. 2  is a connector according to an example embodiment of the invention; 
           [0006]      FIG. 3  is a waveguide according to an example embodiment of the invention; 
           [0007]      FIG. 4  is a waveguide according to an example embodiment of the invention; 
           [0008]      FIG. 5  is a chassis according to an example embodiment of the invention; 
           [0009]      FIG. 6  is a waveguide according to an example embodiment of the invention; 
           [0010]      FIG. 7  is an optical connector according to an example embodiment of the invention; and 
           [0011]      FIG. 8  is a block diagram according to an example embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    A computing system can include modules providing various functions or features. For example, the module may be a processing unit to process instructions and data, a storage unit that may include items such as nonvolatile memory or volatile memory, a communications unit that may connect the computing system to a network, or the module may provide a different function to the computing system. A processing unit for example may include a processor that needs to send data to another processing unit or to a storage unit. The connection between two modules may create a bottleneck where the inter-module data transfer rate exceeds the data processing or handling capabilities of the source module, destination module, or both the source and destination modules. 
         [0013]    The connection between two modules may be limited by the frequency of the signal between the two modules and the propagation of the signal through an electrical conductor such as copper. An optical connection between the two modules may provide a higher transfer rate and more bandwidth compared to a similar connection through a copper conductor. 
         [0014]    In some embodiments the copper conductor connecting two modules may be included in addition to an optical connector. Adding the optical connector to the back of a module can further reduce the airflow through the system and the reduced air flow may cause cooling problems for the system. 
         [0015]    An optical connector may be placed on the top or the bottom of the module. An optical connector may have both a transmitter and a receiver. If a module is installed in a chassis the transmitter and receiver can be aligned so that the transmitter can transmit signals into optical communication path in the chassis and the receiver can receive signals from another optical communication path in the chassis. A first alignment device may be used for the transmitter and a second alignment device may be used for the receiver so that the transmitter and receiver in adjacent modules are properly aligned. The transmitter and receiver can be at different distances from the first side of the module and are located at a different position along the edge of the module. In one embodiment the positions of the transmitter and receiver may create a stair step pattern relative to the first side of the module. 
         [0016]    With reference to the figures,  FIG. 1  is a module according to an example embodiment of the invention. The module  100  can communicate with another module of a computing system to add functionality to the computing system. For example the module may be a processor module to process data, instructions, or both, a storage module to store data, instructions or both, a communications module or another type of module. The module may be a printed circuit board with a component  135  or components attached to the printed circuit board. The printed circuit board may be within an enclosure forming all or a portion of the module. 
         [0017]    The module  100  includes a first side  105 . The module  100  includes a first edge  110 . An optical transmitter connector  115  can be a first distance from the first side  105  at a first position A along the first edge  110 . An optical receiver connector  120  can be a second distance from the first side where the first and the second distances are different. The optical receiver connector  120  can be at a second position B along the first edge  110 . 
         [0018]    The optical transmitter connector  115  and the optical receiver connector  120  can be connected to an optical chip  125 . The optical chip  125  may create an optical signal that carries data received by the optical chip from for example another component. The optical chip  125  may receive optical signals carrying data and send that data to for example another component. The optical transmitter connector  115  and the optical receiver connector  120  may be optically connected to the optical chip  125 . The optical chip  125  may transmit data from a processor, volatile storage such as random access memory, non-volatile storage such as a hard drive, a network connection or another data source. The optical chip  125  may receive data from another module. 
         [0019]    The first position A along the first edge may be adjacent to the second position B. If the first position A and the second position B are adjacent then the optical transmitter connector  115  and the optical receiver connector  120  may be in a stair stepped pattern relative to the first side  105  and may be in a housing  130 . The optical transmitter connector  115  may be in the same or different housing as the optical receiver connector  120 . 
         [0020]    A second module may have the optical transmitter connector  115  and the optical receiver connector  120  in the same or different positions as the first module. If the optical transmitter and receiver connectors are in the same position for each module then the position of a first and a second module would be interchangeable within a chassis. Where the optical transmitters and optical receivers are in different positions in the first and second modules, they can be configured by changing the connection between the optical chip  125 , the optical transmitter connector  115 , and the optical receiver connector  120 . The position of the optical transmitter connector  115  and the optical receiver connector  120  can depend on the design of the first waveguide that connects the optical transmitter on the first module to the optical receiver on a second module and second waveguide that connects the optical receiver on the first module to the optical transmitter on the second module. 
         [0021]      FIG. 2  is a connector according to an example embodiment of the invention. The connector may include a connector housing  130 . The connector housing may include an optical transmitter connector  115 , an optical receiver connector  120 , or both. A resilient member can apply a force between the optical transmitter  115  or optical receiver  120  and a connector on a waveguide. For example the optical transmitter connector or optical receiver connector may be spring loaded to retract or apply force against a waveguide if a connection is made between the module and a waveguide. The optical transmitter or optical receiver connector may also be replaceable if the optical transmitter or optical receiver connector becomes damaged, worn out or is not compatible with the waveguide. 
         [0022]    A connector may have multiple optical receiver connectors. For example a module may have one optical transmitter connector to transmit data to three other modules but have at least one receiver to receive data from the transmitters of each of the three other modules. The number of optical receivers a module includes can be the number of modules that the first module can connect to, for example if 4 modules communicated optically each module may have an optical transmitter and three optical receivers. A module may have more than one optical transmitters and more than one receiver per module it is communicating with to increase the bandwidth of the communication between the modules. An optical cable  135  can extend from the connector housing  130  to connect to an optical chip. There can be an optical cable for each of the connectors. 
         [0023]      FIG. 3  is a waveguide according to an example embodiment of the invention. The waveguide assembly may include a first waveguide  355 , a second waveguide  360 , or more waveguides depending on the communications bandwidth required between interconnected modules.  FIG. 3  shows four waveguides in the assembly. The first waveguide  355  may include a first connector  370 , a second connector  375 , a third connector  380  and a fourth connector  385 . The connectors  370 ,  375 ,  380  and  385  can allow the exit of an optical signal from the waveguide to a receiver or permit the entry of an optical signal from a transmitter to the waveguide. The waveguide may have the same number of connectors as the number of modules that are connected to the waveguide, for example if the waveguide is connected to the optical transmitter or optical receiver of two modules then the waveguide may have two connectors. The connectors  370 ,  375 ,  380  and  385  can have an alignment guide  365  to align an optical transmitter or optical receiver with an opening in the waveguide. The alignment guide may be, for example, three walls with two walls on opposing sides of the connector and the third wall at one end of the connector, the opposite end of the two walls includes an opening for the optical transmitter or optical receiver to enter the alignment guide. The waveguide  355 ,  360  may be, for example, a hollow metal waveguide, an optical fiber, or another light transmitting material. 
         [0024]    If a waveguide of  FIG. 3  was installed in a chassis each of the modules that connect to the waveguides would have to be reconfigured so that the optical transmitter of one module was connected through the waveguide to the optical receivers of another module. If the optical transmitter connector of the first module was in the same position along the first edge of the first module as the position of the optical transmitter connector of the second module then a first module would be connected to the connectors in column  361  and second module would be connected to the connectors in column  362 , and a third module would be connected to connectors in column  363  and a fourth module connected to the connectors in column  364  with the optical transmitters connected to the connectors in row  350  and waveguide  355 . Thus, the waveguide in row  350  would interconnect only optical transmitters and no receivers from the waveguides in row  351 ,  352  and  353  would be connected to these transmitters. If the waveguides in  FIG. 3  were used in the chassis the optical transmitter in one of the modules would have to be moved to another position in the connector housing. For example, if there were only two modules then the optical transmitter connector  115  and the optical receiver connector  120  of  FIG. 2  would have to be reversed. If the optical transmitter from the first module and optical receiver from the second module are connected by reversing the positions data can be transferred between the modules. If however, the optical transmitter of the first module and the optical transmitter of the second module were not reversed the first and the second modules could not communicate. The columns  361 - 364  and rows  350 - 353  of the wave may not be perpendicular to each other so that a connector from an optical transmitter or receiver does not have to pass over the connector in a different waveguide than the connector the connector was suppose to connect to. 
         [0025]      FIG. 4  is a waveguide according to an example embodiment of the invention. The waveguide can include a first waveguide  355  connected to a second waveguide  356  through a flexible waveguide  357  such as a fiber optic cable. Portions of the waveguides  355  and  356  are in different rows  350  and  353 . Having the waveguides partially in different rows may allow the modules to be designed with the optical transmitters and the optical receivers in the same position on different modules. For example the row  350  may be connectors for optical transmitters and rows  351 ,  352 , and  353  can be connectors for optical receivers. The connector  370  in row  350  may be a connector for an optical transmitter and the connectors  375 ,  380  and  385  in row  353  may be connectors for optical receivers while connectors  370 ,  375 ,  380  and  385  are in different columns  361 ,  362 ,  363 , and  364 . 
         [0026]      FIG. 5  is a chassis according to an example embodiment of the invention. The chassis  590  can include for example a first slot  595  in the chassis to receive a first module  500  and a second slot  596  in the chassis to receive a second module  501 . A first waveguide  555  with a first connector located a first distance from a side of the first slot  595  and at a first position along the side of the first slot; and a second waveguide  560  with a second connector located a second distance from the side of the first slot at a second position along the side of the first slot. The first connector on the first waveguide may be aligned with the optical transmitter  315  and the second connector on the second waveguide may be aligned with the optical receiver  520  of the first module  595 . There may be multiple optical transmitters  515  and receivers  520  connected to each of the other modules  501 ,  502  and  503  through the waveguides  555  and  560  between the slots  595 ,  596 ,  597  and  598  to increase the bandwidth of data transmission between the first module and the second module. 
         [0027]      FIG. 6  is a waveguide  600  according to an example embodiment of the invention. The waveguide can include connectors  670 ,  675 ,  680 , and  685  in multiple columns  361 ,  362 ,  363 , and  364 . The connectors in each of the different rows  351 ,  352 ,  353  and  354  may have different shapes or sizes so that a connector for row  353  does not connect to the connector  670  in row  351  as the module is inserted in the chassis prior to being fully inserted in the chassis. 
         [0028]      FIG. 7  is an optical connector according to an example embodiment of the invention. The optical connector  730  includes optical transmitter connectors  715  and optical receiver connectors  720 . The optical transmitter connector does not have to be the first connector in the connector and may be in any position on the optical connector  730 . The connectors can be different sizes and different shapes to prevent the one of the connectors from connecting to one of the rows of the waveguide  600  before the connector is in the correct row to connect to the waveguide  600 . 
         [0029]      FIG. 8  is a block diagram according to an example embodiment of the invention. The first module  800  can include a component  835  that is connected to an optical chip  825 . The component  835  may be storage, a processor, an input output controller or another component. The optical chip  825  can be connected to the transmitter  815  and the receiver  820 . The waveguide  855  can connect the optical transmitter  815  of the first component  800  to the optical receiver  820  of the second component  801 . The waveguide  860  can connect the optical receiver  820  of the first module  800  to the optical transmitter  815  of the second module  801 . The component  835  in the first module may be the same as component  836  in the second module or may be different components. For example if the first module  800  was a processor module the component  835  may be a processor and if the second module  801  was a storage module the component  836  may be a storage device such as a hard drive although the components  835  and  836  can be other components as well. 
         [0030]    In the foregoing description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these details. While the invention has been disclosed with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover such modifications and variations as fall within the true spirit and scope of the invention.