Crossbar switch

There are two DSP-32s per processor module . The master (with external memory) is connected to the serial lines going to and from the crossbar switch. The slave is connected to external I/O devices such as A/D and D/A converters. It is... 

DIRECT DATA HAND-OFF BETWEEN 16 FUNCTIONAL UNITS THROUGH CROSSBAR SWITCH PROVIDES BROADEST CAPABILITY FOR MULTIPLE CHAINING WITH NO REQUIREMENTS ON OPERAND INDERDEPENDENCE... 

Nodes often provide multiple sockets, each of which can accommodate a multicore chip (two or four sockets are common, and three-socket configurations exist as well). Figure 2.15 shows an example of a node architecture based on the quad-core AMD Opteron chip. Each chip has four cores (or processors, as we use the term here). Each core has its own first (LI) and second (L2) level caches. All four cores share the third level cache (L3). A crossbar switch connects the processors to two memory controllers for accessing off-chip memory. The crossbar has three additional high-speed links that can be used to connect other multicore chips or input/output devices. 

An example node consisting of four quad-core AMD Opteron chips. Memory, processors, and the parallel machine interconnect are reached though a ring network formed by connecting the crossbar switches. A single quad-core AMD Opteron chip provides four cores (C0-C3), two memory controllers, the System Request Interface (SRI), the crossbar, and the LI, L2, and shared... 

Shared memory computers in which all processors have equal access to all memory in the system are referred to as symmetric multiprocessors (SMP), and may also be called uniform memory access (UMA) computers. In the node shown in Figure 2.15, references to memory may need to pass through one, two, or three crossbar switches, depending on where the referenced memory is located. Thus, this node technically has a nonuniform memory access (NUMA) architecture, and, since the node is cache-coherent, this architecture is called ccNUMA. However, since the crossbar switches in the quad-core AMD Opteron implementation of ccNUMA exhibit high performance, this particular node would typically be considered to be an SMP. 

One of the best shadow logic crossbar switches was the one demonstrated on the... 

Besides self-assembly on the surface of metals, another example of self-assembly is the formation of Langmuir-Blodgett monolayers on the surface or at the interface of liquids.47,48 One approach to molecular-based electronic devices that has made use of self-assembled Langmuir-Blodgett films is the crossbar-based defect-tolerant approach to molecular computing 49 Rotaxane molecules that depend on physical dislocations within the molecule to produce switching functionality have been designed such that they will... 

Molecular switches in the junctions of metallic crossbar arrays... 

The careful design and delicate synthesis of a number of catenanes and rotaxanes have led to their incorporation into monolayers, and then from these monolayers in the form of Langmuir-Blodgett films onto patterned silicon substrates. This step, followed by the deposition of a second metal layer in the perpendicular direction to form a crossbar, has resulted in the production of an ever-growing number of electrical devices in which the switching is carried out at junctions one molecule thick. 

In the most recent iteration of the feedback loop which relates molecular structure to solid-state device performance, the fast bistable [2]rotaxane 11" has been superseded " by the modified and improved version shown in Fig. 1.15, namely, the [2]rotaxane The impetus for this iteration was at least two-fold (1) to produce a molecular switch in which the bistable rotaxane starts off exclusively in one, and only one, of its two possible co-conformations and (2) to incorporate into this all-or-nothing switch enhanced oxidative stability by removing all of the phenolic residues from the hydrophilic stopper. The rotaxane, which was obtained (Fig. 1.15) by the now well-established templation protocol, has been incorporated by the familiar fabrication procedures into an 8 x 8 crossbar device (Fig. 1.16(a)). Fig. 1.16(b) demonstrates one of these 64-bit devices in operation with the exception of one of the wires, i.e., 56 out of the 64 bits can be switched. This device has been used to store (Fig. 1.16(c)) the letters DARPA in ASCII code the lifetime of the switch-closed state of this devices is about 10 minutes. The proposed electromechanical switching mechanism for the bistable [2]rotaxane which is outlined in Fig. 1.17, merits comparison with that already discussed in Fig. 1.16 for the bistable [2]rotaxane In the case of it is proposed that oxidation of the TTF unit to its radical cation (TTF ) occurs when a +2 V bias is applied across the bistable [2]rotaxane and the tetracationic cyclophane moves to encircle the... 

Fig. 1.16 (a) The demonstration of point addressablity within a 64-bit molecular switch crossbar circuit utilized as a molecular RAM. This... 

Fig. 1.18 A SEM image composed of a nanometer-scale molecular switch crossbar circuit.

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