Abstract:
Device, system, and method of flexible hardware connectivity. For example, a Printed Circuit Board (PCB) system includes: a rigid platform having embedded therein at least one programmable logic device; at least one rigid panel having embedded therein a set of connectors; and a flexible connection to flexibly connect, at a non-straight angel, the programmable logic device to the rigid panel along a folding axis of the rigid panel and the rigid platform, wherein a density of wires of the flexible connection is greater than a density of wires entering at least one of the connectors.

Description:
PRIOR APPLICATION DATA 
       [0001]    The present application claims priority and benefit from United States Provisional Patent Application No. 60/897,050, titled “Device, System and Method of Flexible Connectivity”, filed on Jan. 24, 2007, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD 
       [0002]    Some embodiments of the invention are related to the field of Field Programmable Gate Arrays (FPGAs) connectivity. 
       BACKGROUND 
       [0003]    A backplane may include multiple Field Programmable Gate Arrays (FPGAs), for example, soldered into rigid boards. 
         [0004]    Unfortunately, a significant amount of logical components and electronics included on the rigid boards may require a complex connectivity, physical proximity of the rigid boards and a highly branched wiring. 
       SUMMARY 
       [0005]    Some embodiments of the invention include, for example, devices, systems, and methods of flexible hardware connectivity. 
         [0006]    In some embodiments, a Printed Circuit Board (PCB) system includes: a rigid platform having embedded therein at least one programmable logic device; at least one rigid panel having embedded therein a set of connectors; and a flexible connection to flexibly connect, at a non-straight angel, the programmable logic device to the rigid panel along a folding axis of the rigid panel and the rigid platform, wherein a density of wires of the flexible connection is greater than a density of wires entering at least one of the connectors. 
         [0007]    In some embodiments, substantially each connector includes a mechanism to transform a plurality of wires of the flexible connection into a socket connection. 
         [0008]    In some embodiments, the rigid panel is connected through the flexible connection with the rigid platform at an angle of approximately 90 degrees. 
         [0009]    In some embodiments, the rigid panel is connected through the flexible connection with the rigid platform at an angle generally different from 90 degrees. 
         [0010]    In some embodiments, the flexible connection includes at least a number of wires sufficient to logically connect the programmable logic device to the set of connectors. 
         [0011]    In some embodiments, the PCB system includes: a flexible bridge to directly interconnect between the set of connectors and another set of connectors associated with one or more programmable logic devices external to the rigid platform. 
         [0012]    In some embodiments, the flexible connection includes at least 600 wires per programmable logic device. 
         [0013]    In some embodiments, at least one of the one or more programmable logic devices includes a Field Programmable Gate Array (FPGA). 
         [0014]    In some embodiments, the PCB system includes: another rigid panel having embedded therein another set of connectors; and another flexible connection to flexibly connect, at a non-straight angel, the programmable logic device to the rigid panel along a folding axis of the rigid panel and the rigid platform. 
         [0015]    In some embodiments, the PCB system includes at least one more programmable logic device embedded in the rigid platform. 
         [0016]    In some embodiments, at least two of the programmable logic devices embedded in the rigid platform are interconnected. 
         [0017]    In some embodiments, at least two of the programmable logic devices embedded in the rigid platform are interconnected using an interconnection including between 199 and 401 wires. 
         [0018]    In some embodiments, one or more connectors of the set of connectors are directly connected to a component of a first of the programmable logic devices, and one or more other connectors of the set of connectors are directly connected to a component of a second of the programmable logic devices. 
         [0019]    In some embodiments, the flexible connection includes: at least one set of two differential wires capable of operating in transmission-only mode; and at least one other set of two differential wires capable of operating in reception-only mode. 
         [0020]    In some embodiments, at least one of the connectors includes a non-right-angle connector. 
         [0021]    In some embodiments, a system for Printed Circuit Board (PCB) units includes: a rack capable of storing a set of PCB units, the rack including: a set of cavities to store the set of PCB units, and one or more PCB unit insertion mechanisms; wherein each PCB unit includes: a rigid platform having embedded therein at least one programmable logic device; at least one rigid panel having embedded therein a set of connectors; and a flexible connection to flexibly connect, at a non-straight angel, the programmable logic device to the rigid panel along a folding axis of the rigid panel and the rigid platform, wherein a density of wires of the flexible connection is greater than a density of wires entering at least one of the connectors. 
         [0022]    In some embodiments, at least one of the insertion mechanisms includes a slide-in/slide-out mechanism. 
         [0023]    In some embodiments, at least one of the insertion mechanisms includes one or more rails. 
         [0024]    In some embodiments, at least one of the insertion mechanisms includes one or more slots, and a PCB unit is insertable into the one or more slots. 
         [0025]    In some embodiments, rack includes a housing which includes: a first horizontal surface; a second horizontal surface generally parallel to the first horizontal surface; a first vertical surface; and a second vertical surface generally parallel to the first vertical surface; the rigid panel is at an angle of approximately 90 degrees with the first horizontal surface, and the rigid panel is at an angle of approximately 90 degrees with the first vertical surface. 
         [0026]    In some embodiments, the system includes: another rack capable of storing another set of PCB units, and the racks are interconnected using one or more flexible connections. 
         [0027]    In some embodiments, the system includes: a flexible connection capable of physically connecting between: a programmable logic device of any of the PCB units of a first rack of the racks, and a programmable logic device of any one of the PCB units of a second rack of the racks. 
         [0028]    Some embodiments of the invention may provide other and/or additional benefits and/or advantages. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    For simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity of presentation. Furthermore, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. The figures are listed below. 
           [0030]      FIG. 1  is a schematic illustration of a Field Programmable Gate Array (FPGA) tray, in accordance with some demonstrative embodiments of the invention. 
           [0031]      FIG. 2  is a schematic illustration of three interconnected FPGA trays, in accordance with some demonstrative embodiments of the invention. 
           [0032]      FIG. 3  is a schematic illustration of a rigid board with electronics and side connectors, in accordance with some demonstrative embodiments of the invention. 
           [0033]      FIG. 4  is a schematic illustration of multiple rigid boards, in accordance with some demonstrative embodiments of the invention. 
           [0034]      FIG. 5  is a schematic illustration of a rigid board with electronics and a rigid-flex Printed Circuit Board (PCB), in accordance with some demonstrative embodiments of the invention. 
           [0035]      FIG. 6  is a schematic illustration of a three dimensional architecture of a system, in accordance with some demonstrative embodiments of the invention. 
           [0036]      FIG. 7  is a schematic illustrates a three dimensional architecture of a system, in accordance with some demonstrative embodiments of the invention. 
           [0037]      FIG. 8  is a schematic illustration of a system of rigid boards housed in multiple racks, in accordance with some demonstrative embodiments of the invention. 
           [0038]      FIG. 9  is a schematic illustration a multi-rack system having first and second racks, the first rack located on top of the second rack, in accordance with some demonstrative embodiments of the invention. 
           [0039]      FIG. 10  is a schematic illustration of a set of identification pins, in accordance with some demonstrative embodiments of the invention. 
           [0040]      FIG. 11  is a schematic block diagram illustration of a FPGA tray, in accordance with some embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0041]    In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of some embodiments of the invention. However, it will be understood by persons of ordinary skill in the art that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, units and/or circuits have not been described in detail so as not to obscure the discussion. 
         [0042]    The terms “Field-Programmable Gate Array” (FPGA) or FPGA unit as used herein includes, for example, a semiconductor device containing programmable logic components (e.g., logic blocks, logic gates, memory blocks, or the like) and programmable interconnects. 
         [0043]    The term “FPGA unit” as used herein includes, for example, a single FPGA, a pair of two interconnected FPGAs, a set of multiple interconnected FPGAs, or the like. In some embodiments, the terms “FPGA” or “FPGA unit” may optionally include non-FPGA components, for example, a logic device, a programmable logic device, a connectivity device, or the like. 
         [0044]    Although portions of the discussion herein relate, for demonstrative purposes, to a rigid board having FPGAs or to FPGA units, embodiments of the invention are not limited in this regard and may be used, for example, in conjunction with other logic devices, programmbale logic devices, PHY devices (for example, Ethernet PHY devices, display or imaging devices), non-programmable logic devices, dedicated logic devices, connectivity devices, or a combination thereof. 
         [0045]    Although portions of the discussion herein relate, for demonstrative purposes, to a rigid board having two FPGAs or two FPGA units, embodiments of the invention are not limited in this regard and may be used, for example, in conjunction with rigid boards having a single FPGA or a single FPGA unit, rigid boards having three FPGAs or FPGA units, or four (or other numbers of) FPGAs or FPGA units. In some embodiments, two or more of the FPGAs (or FPGA units) located on a common rigid board may be interconnected using one or more connections or wires (or groups of connections or wires), may share one or more connections or wires (or groups of connections or wires), or the like. In some embodiments, various rigid boards or “trays” may include different numbers of FPGAs and/or other programmable logic devices. 
         [0046]      FIG. 1  schematically illustrates a FPGA tray  100  in accordance with some demonstrative embodiments of the invention. In some embodiments, tray  100  may include two FPGA units, for example, unit  115  and unit  116 . FPGA units  115 - 116  may be soldered together or otherwise connected onto a single platform or rigid board  113 , or may be included in a single housing. In some embodiments, FPGA units  115 - 116  may include electronics, electronic units and/or logical units, for example, memory blocks, chips, processors, resistors, circuits, logic blocks, logic gates, or the like. FPGA units  115 - 116  may be interconnected using one or more connections  140 . 
         [0047]    Wire ensembles (or other suitable flexible connectivity members)  120  and  130  may connect between FPGA units  115  and  116 , and connectors  121 - 126  and  131 - 136 . In some embodiments, for example, wire ensemble  120  may be associated with unit  115 , and may be located on a side of rigid board  113 ; Wire ensemble  130  may be associated with unit  116 , and may be located on an opposite side of rigid board  113 . In other embodiments, for example, a first portion of wire ensemble  120  may be associated with components of FPGA unit  115 , whereas a second portion of wire ensemble may be associated with components of FPGA unit  116 . Similarly, a first portion of wire ensemble  130  may be associated with components of FPGA unit  115 , whereas a second portion of wire ensemble  130  may be associated with components of FPGA unit  116 . 
         [0048]    Wire ensembles  120  and  130  include multiple wires, cables, links, conductive materials, or the like. In some embodiments, for example, wire ensembles  120  and  130  may include approximately 720 wires, approximately, 710 wires, approximately 700 wires, approximately 730 wires, approximately 740 wires, between 710 and 730 wires, between 700 and 740 wires, or the like. Additionally, wire ensembles  120  and  130  may be flexible, as to allow decks or panels  112  and  114 , respectively, to form multiple angles with rigid board  113  or to form a three dimensional structure including rigid board  113  and panels  112  and  114 , e.g., a U shaped structure. In some embodiments, for example, panels  112  and  114  may form an angle of approximately 90 degrees with rigid board  113 . In other embodiments, other suitable angles may be formed. Although portions of the discussion herein relate, for demonstrative purposes, to wire ensembles  120  and  130  having approximately 720 wires, embodiments of the invention may utilize other number of wires, for example, approximately 250 wires, approximately 1,000 wires (e.g., utilizing three FPGAs per rigid board), approximately 2,000 wires (e.g., utilizing three FPGAs per rigid board having substantially all connections on one side), hundreds or thousands or wires, or the like. 
         [0049]    Wire ensemble  120  transfers data from FPGA units  115 - 116  to connectors  121 - 126 , and vice-versa. For example, a first portion of wires of wire ensemble  120  may be associated with a first component of unit  116  and connected to a first connector, for example, connector  121 ; a second portion of wires of wire ensemble  120 , possibly associated with a second component of FPGA unit  116 , or a component of FPGA unit  115 , may be connected to a second connector, for example, connector  123 . Similarly, a first portion of wires of wire ensemble  130  may be associated with a first component of FPGA unit  115  and connected to a first connector, for example, connector  132 ; a second portion of wires of wire ensemble  130 , possibly associated with a second component of FPGA unit  115 , or a component of FPGA unit  116 , may be connected to a second connector, for example, connector  123 . Connectors  121 - 126  and/or  131 - 136  may include an inner wiring mechanism, transforming multiple wires of wire ensembles  120  and/or  130  associated therewith to a single connection. For example, connector  121  may be associated with multiple wires of wire ensemble  120 , and when externally connected to another connector using a bridge, as described herein, the bridge is implemented as a single wire or a single wire unit. 
         [0050]    Although portions of the discussion herein relate, for demonstrative purposes, to flexible wire ensembles  120  and  130 , embodiments of the invention are not limited in this regard and may be used, for example, in conjunction with non-flexible wire ensembles  120  or  130 , e.g., allowing the panel  112  to be rigidly or semi-rigidly connected to rigid board  113 , and/or allowing the panel  114  to be rigidly or semi-rigidly connected to rigid board  113 , optionally at a right angle of 90 degrees or other suitable (e.g., constant) angles. 
         [0051]      FIG. 2  schematically illustrates three interconnected trays  210 ,  220  and  230 , in accordance with some demonstrative embodiments of the invention. Each one of trays  210 ,  220  and  230  may be similar to tray  100  of  FIG. 1 . Some embodiments may allow interconnecting multiple trays, including, for example, physically remote trays. For example, a first connector  212  associated with tray  210  is connected to a connector  231  associated with tray  230 , using a bridge  215 . A second connector  211  associated with tray  210  is connected to connector  221  associated with tray  220 , using bridge  225 . Similarly, trays  220  and  230  are connected using bridges  245  and  255 . Bridge  255  interconnects connectors  228  and  238  associated with trays  220  and  230 , respectively. Bridge  245  interconnects connectors  226  and  232  associated with trays  220  and  230 , respectively. A bridge  265  connects connectors  222  and  223 , both located on tray  220 , thereby connecting externally multiple components of tray  220 . Trays  210 ,  220 ,  230  and/or additional trays may be located one on top of another, besides one another, physically remote one from the other, oriented sideways relative to one another, in a diagonal structure, in a three-dimensional structure, embedded or housed in a common housing or rack or backplane, or in multiple housings or racks or backplanes, or a combination thereof, or the like. Multiple other connections between two connectors may be applied using additional bridges, for example, allowing direct physical and/or logical connectivity (and optionally utilizing indirect physical connectivity) between substantially every pair of connectors, associated with random components of random trays. Bridges  215 ,  225 ,  245 ,  255 , and/or  265  may transfer data or information including high frequency signals, and may be flexible. 
         [0052]      FIG. 3  schematically illustrates a rigid board with electronic components and side connectors, in accordance with some demonstrative embodiments of the invention. In some embodiments, multiple systems, such as IC or System on Chip (SoC) or ASIC Verification or Prototyping, combine a significant number of logic and electronic components with a significant number of unpredictable high-speed connection lines to interconnect multiple parts of the logic and electronic components. Accordingly, in some embodiments, a system may include multiple rigid boards to house the multiple logic and electronic components. Some embodiments may include a significant number of logic and electronic components, as well as high flexibility for huge and unpredictable I/Os density with high-speed performance. In some embodiments, a rigid board including the electronic components and multiple I/O connectors may be located on multiple axes. 
         [0053]    For example, a rigid board  300  housing electrical components and side connectors  301 - 304  form an angle of approximately 90 degrees. In other embodiments, other angles may be formed, for example, approximately 83 degrees, approximately 104 degrees, approximately 35 degrees, approximately 56 degrees, approximately 120 degrees, approximately 127 degrees, or the like. 
         [0054]      FIG. 4  schematically illustrates multiple rigid boards, in accordance with some demonstrative embodiments of the invention. In some embodiments, connectors may be placed generally along sides of the rigid board, for example, to increase the number of possible I/Os associated with a rigid board. For example, rigid board  410  has connections in two sides, connectors  411  and  412  on a first side, and connectors  413  and  414  on a second, generally opposite side. Similarly, rigid board  420  has connections in two sides, connectors  421  and  422  on a first side, and connectors  423  and  424  on a second, generally opposite side. For example, rigid boards  410  and  420 , and possibly similar rigid boards may be located next to one another. Architecture of the rigid boards allows a three-dimensional electronics location, and multiple rigid boards are possibly externally connected. Additionally, this architecture may allow full air flow that may be needed in order to cool the electronics. 
         [0055]      FIG. 5  schematically illustrates a rigid board with electronics and a flex-rigid Printed Circuit Board (PCB), in accordance with some embodiments of the invention. In some embodiments, a first area including electronic components and a second area including connectors may be physically separated, for example, for routing purposes. For example, rigid board  500  may include electronic components and logic components, and may be connected to rigid connectors  511  and  512 , via flexible connections  501  and  502 , respectively. Flexible connections  501  and  502  may include multiple inner wires, for example, approximately 118 or 120 wires, approximately 110 wires, approximately 130 wires, between 110 and 130 wires, or other suitable number of wires (for example, groups of approximately 10 wires, 120 wires, 180 wires, 240 wires, 300 wires, hundreds or thousands of wires, or the like), coated with a uniform coat. This may allow, for example, forming an angle between the rigid board and the connectors, as described herein. Additionally, some embodiments may allow adding electronics in multiple portions, for example, in connectors  511  and  512 , as well as in connectors included in electronics of rigid board  500 . 
         [0056]      FIG. 6  schematically illustrates a three dimensional architecture of a system, in accordance with some embodiments of the invention. Connectivity between rigid boards may be flexible and fast. For example, system  600  may include ten rigid boards  601 - 610 , located in the vicinity of one another, housed in a rack  630 . In some embodiments, assembly of the rigid boards in a three-dimensional array results in a location of multiple connectors on every side, facing a single direction, thereby suitable to be comfortably connected. External bridges, for example, bridges  611 - 614 , may externally connect connectors of different rigid boards, one with the other. 
         [0057]      FIG. 7  schematically illustrates a three dimensional architecture of a system, in accordance with some embodiments of the invention. In some embodiments, a generally complete connection may be achieved, by connecting several segments, such that substantially every segment connects a part of the system. An overall system flexibility and connectivity, together with maximum speed performance, may be obtained using multiple connections between similar or dissimilar segments in multiple locations. System  700  may include ten rigid boards  701 - 710 , located in a vicinity of one another, and housed in a rack  730 . For example, generally every rigid board has two connectors on each of the three panels in every side. A connector represents connectivity to a specific component on the rigid board. For example, connectors  716  and  717  connect signals to specific components in rigid boards  706  and  707 , respectively. Bridge  721  connects between two internal elements in rigid board  705 , via an external connection. Bridge  722  connects between a component included in rigid board  706 , and a component included in rigid board  707 . Bridge  723  yields a bus connection, namely, a connection between physically remote rigid boards. 
         [0058]      FIG. 8  schematically illustrates a system of rigid boards, housed in multiple racks, in accordance with some embodiments of the invention. In some embodiments, rigid boards and frames, or racks, may be connected side by side. In some embodiments, for example, the architecture shown in  FIG. 8 , may allow a simple connection between a first element in a first rigid board included in a first rack, and a second element in a second rigid board, included in a second rack, for example, when the rigid boards and/or racks are located side by side. For example, system  800  may include a first set of rigid boards belonging to a first rack  810 , and a second set of rigid boards belonging to a second rack  820 . For example, rigid board  821  of rack  820  may be connected to a first rigid board,  811 , of rack  810 , using an inter-rack connection bridge  831 . Similarly, rigid board  821  of rack  820  may be additionally connected to a second rigid board  812  of rack  810 , using an inter-rack connection bridge  832 . 
         [0059]      FIG. 9  schematically illustrates a multi-rack system  100  having a first rack  910  and a second rack  920 , the first rack  910  located on top of the second rack  920 , in accordance with some demonstrative embodiments of the invention. As described herein, a three-dimensional architecture may allow connecting of two connectors, included in two separate racks, externally. For example, a connector  915  of rigid board  911  of rack  910 , and a connector  925  of rigid board  921  of rack  920 , may be connected using a connection bridge  931 . Additional connections are shown. 
         [0060]      FIG. 10  schematically illustrates a set of identification pins, in accordance with some demonstrative embodiments of the invention. In some embodiments, for example, a connection unit yields a connection between a connector on one rigid board with an additional connector on the same rigid board or on a different rigid board. In some embodiments, for example, a connector has a dedicated pin for identification purposes. A connection between two connectors connects corresponding identification pins. A dedicated identification pin of a connector is connected to a pull-up on the rigid board to which the connector is associated. Connectivity identification may include connecting a logical value, for example, a “0”, to a specific dedicated pin. The identification may include, for example, scanning dedicated pins associated with other connectors and listing connectors, that have pin input of logical “0”, as connected to the specific dedicated pin. The identification may include repeating the procedure with other dedicated pins, one by one, to have all connection lists. For example, connectors  1002 - 1004  and  1006  are connected together. When assigning a “0” value to connector  1002 , connectors  1002 ,  1003 ,  1004  and  1006  will read a “0” value and all the other slots will read a “1” value. Thereby, a connection between connectors  1002 - 1004  and  1006  may be detected. Similarly, when assigning a “0” value to connector  1001 , connectors  1002 ,  1003 ,  1004  and  1006  show an associated “1” value, thereby showing that they are not connected to connector  1001 . 
         [0061]    In other embodiments, for example, a similar identification method may be used, without dedicated pins for identification. In the identification, one or more nominal pins may be used in double function. For example, during the system identification test, the nominal pin is used as a connectivity identifier, whereas during operation of a system, the nominal pin is used as a regular pin. In other embodiments, for example, identification pins may provide identification and/or setup protocols allowing to add various types of logic. This may provide a solution to complex hardware problems for building, IC/SoC/ASIC development equipment, for example, verification systems, emulators and prototyping environment. 
         [0062]    Some embodiments may include a significant amount of connections, allowed by having as many levels of connectors as required, in every side of the rigid board, connected as described herein. 
         [0063]    In some embodiments, in which a system is utilized, for example, for design verification of IC/Soc/ASIC, the system may allow to include a considerable amount of electronic components as well as a considerable amount of flexible connectors. Some embodiments of the invention may allow a cooling of the system, maintainability, upgradeability and/or other features. In some embodiments, in which electronic components on the rigid boards (for example, FPGAs) are required to be connected, a fast on-board connection between the FPGAs may be utilized, regardless of the location thereof, for example, including in a case in which connected FPGAs are embedded on multiple rigid boards included in multiple racks. In some embodiments, a direct connection between generally every pair or group of FPGAs or other logic devices may be utilized. 
         [0064]      FIG. 11  schematically illustrates a block diagram of a FPGA tray, in accordance with some embodiments of the invention. In some embodiments, a FPGA tray  1100  may include two FPGA units  1101  (FPGA  1 ) and  1102  (FPGA 2 ), soldered together, or otherwise embedded, on a rigid board  1103 , connected using a connection  1150 . Connection  1150  may include, for example, one or more wires, two wires, one or more dozens of wires, one or more hundreds of wires, one or more thousands of wires, approximately 260 wires or the like. In some embodiments, optionally, connection  1150  may not be included in the FPGA tray  1100 , or may include substantially no wires, such that FPGA units  1101  and  1102  are not inter-connected. FPGA tray  1100  may include a front panel  1110  and a back panel  1120 . In some embodiments, front panel  1110  and back panel  1120 , may include connectors  1111 - 1116  and  1121 - 1126 , respectively. In  FIG. 11 , the letter “J” in a label of a connector represents the word “jack”, or socket, or the like. The letter “F” in a label of a connector represents the word “front”, indicating that the labeled connector is located in front panel  1110 . The letter “B” in a label of a connector represents the word “back”, indicating that the labeled connector is located in back panel  1120 . The digit “1” in a label of a connector, indicates that the labeled connector is associated with unit  1101 . The digit “2” in a label of a connector, indicates that the labeled connector is associated with unit  1102 . The letter “D” in a label of a connector represents the term Double Data Rate (DDR), indicating that the labeled connector is associated with a memory of units  1101  or  1102 . The letter “T” in a label of a connector represents the word “transmitter”, indicating that the labeled connector is associated with a transmission of data from units  1101  or  1102 . The letter “R” in a label of a connector represents the word “receiver”, indicating that the labeled connector is associated with a receiving of data to units  1101  or  1102 . 
         [0065]    In some embodiments, unit  1101  may be connected to connectors  1111 - 1116 , using external connections  1121 - 1126 , respectively. A connection from connections  1121 - 1126  may include, for example, approximately 118 wires, or approximately 120 wires, or the like. Similarly, unit  1102  may be connected to connectors  1131 - 1136 , using external connections  1141  - 1146 , respectively. A connection from connections  1141 - 1126  may include, for example, approximately 118 wires, or approximately 120 wires, or the like. 
         [0066]    Some embodiments, for example, may allow interconnecting efficiently and rapidly a system including multiple FPGA trays (e.g., 3 trays, 10 trays, 30 trays, 50 trays, 100 trays, or the like), thereby including approximately 100 million equivalent ASIC gates, or more. In some embodiments, a system may be designed to operate at system clock speeds of up to 300 Megahertz or other suitable clock speeds or clock frequencies in accordance with available technology. In some embodiments, a rapid locating of bugs in a system may be allowed. 
         [0067]    Some embodiments may utilize a scalable capacity within each system, varying from 5 million to 30 million equivalent ASIC gates. 
         [0068]    Some embodiments may utilize significant connection flexibility, for example, 974 user Inputs/Outputs (I/Os) per FPGA, of which 708 I/Os may be directly connected to substantially any other FPGA. In some embodiments, a system may utilize up to 14,160 high-speed user I/Os to connect the system to hardware of a user or other systems. In some embodiments, a system may include 4,720 DDR I/Os of 250 Megahertz, and/or 2,320 LVDS RX channels of 1 Gigahertz, and/or 2,320 LVDS TX channels of 1 Gigahertz, and/or 14,160 single-ended speed I/Os. 
         [0069]    Some embodiments may utilize high-speed connectivity, for example, of 300 Megahertz for single ended lines, or of 250 Megahertz for DDR I/Os, or of one Gigahertz for Low Voltage Differential Signal (LVDS) channels. 
         [0070]    Some embodiments may utilize an open infrastructure for user add-on logic and future technology. Some embodiments may utilize up to 1,280 Megabytes of DDR II memories. Some embodiments may utilize Multi-Volt I/Os, allowing selections of different protocols and I/O voltages, for example, voltages of 1.5 volts, or 1.8 volts, or 2.5 volts and/or 3.3 volts. Some embodiments may include a modular rack containing 10 slots (into which a FPGA tray may be inserted, and out of which the FPGA tray may be removed) for a scalable FPGA platform, as well as a set of bridges or connections, for I/O connections. 
         [0071]    In some embodiments, LVDS RX and LVDS TX I/Os may be utilized as dual-purpose I/Os. Additionally, LVDS RX and LVDS TX I/Os may be used as single ended bidirectional signals. 
         [0072]    Some embodiments may include a 64 Megabyte DDR II DRAM block for a FPGA. Some embodiments may include a Multi-Port controller, allowing a DDR II DRAM block to be accessed via multiple First-In-First-Outs (FIFOs), thereby allowing rapid ensuring, as well as wide and flexible data steaming. This enables fast pattern injection from a network host, as well as a significant depth of signal tracing. In some embodiments, a size of a system including, for example, 10 FPGA trays, may be approximately 61 centimeters of length, approximately 30 centimeters of width and approximately 55 centimeters of height. A system may include a slide-in-slide-out mechanism, for example, one or rails or wheels, allowing to slide-in and/or to slide-out an individual FPGA tray, e.g., into or out of a rack or a backplane of a system. Other suitable insertion or storage mechanisms may be used, for example, to allow FPGA trays to be inserted or placed, e.g., one on top of another, side by side, or the like. 
         [0073]    Although portions of the description herein relate, for demonstrative purpose, to “first” and “second” FPGAs or programmable logic devices, embodiments of the invention may be used in conjunction with more than two FPGAs or programmable logic devices, and a “second” FPGA or programmable logic device may include “another” FPGA or programmable logic device. In some embodiments, a FPGA tray may include a single FPGA unit, and may not necessarily include two or more FPGA units. 
         [0074]    While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes.