Priority encoder

In a casex statement, the values x and z ( for a z is ok too) in a case item expression are considered as don t-care values. These values, for synthesis purposes, cannot appear as part of the case expression. Here is an example of a casex statement used to model a priority encoder. 

Figure 2-32 A priority encoder using casex statement.

In Verilog HDL, it is possible to have a non-constant expression as a case item. This is shown in the following example of a priority encoder. 

Figure 2-38 Priority encoder using case statement, case (l bl)...

The readout of the cathode plane is somewhat more complicated, since the induced signals extend over several elements. The determination of the position of the avalanche is done by the so-called center of cluster method. The thresholds of the discriminators are chosen such that the induced signal of several cathode wires switches them (see Fig. 13). Two priority encoder systems are connected to the cathode plane in opposite directions. Priority encoders produce the address of the highest numbered input element which receives a signal. Since the systems are connected in opposite directions, system A will deliver the address of the higher numbered cathode wire whose signal is above the threshold value. System B gives the address of the lower wire. 

A system based on one amplifier per wire and priority encoder is in use at the synchrotron radiation faciUty LURE in Orsay, France. The 448 x 448 mm MWPC, with a spherical drift space to avoid paralaxes in crystallographic experiments, has been developed at CERN, Geneva . The spatial resolution is (2x2)mm, ... 

A decoder example, a priority encoder example, the MC68000, a multiplier example, and a cell for a sorting stock example. 

In this section, we discuss some basic issues related to HDL coding for synthesis such as VHDL types, unwanted latches, variables and signals, and priority encoding. For a certain desired functionality, it is often possible to code HDL in a number of different ways. However, there are several guidelines that one can follow to develop a consistent coding style for synthesis. 

Coding with if statements causes priority encoding logic to be inferred. In other words, DC assumes that the first if condition has a greater priority than the second and so on. To avoid this one must use case statement. Refer to Scenario 3 in section 2.1. 

Fig. 1.4 Phase encoding scheme in three ween the rf pulses and before the acquisition of dimensions. Three pulsed gradients in ortho- the echo signal. In practice, the gradients are gonal directions are applied and are varied often applied simultaneously. The indices 1, 2 independently of each other (symbolized by the and 3 represent orthogonal directions with no diagonal line). The actual timing of the gradi- priority being given to a particular choice of ents is arbitrary provided they are placed bet- combinations.

The amino acid components of proteins have the L conhguration (see Section 3.4.10), but many peptides are known that contain one or more D-amino acids in their stmctures. o-Amino acids are not encoded by DNA, and peptides containing them are produced by what is termed non-ribosomal peptide biosynthesis (see Section 13.5.2). o-Amino acids generally arise by epimerization of L-amino acids (see Box 10.10). All the protein L-amino acids have the S conhguration, except for glycine, which is not chiral, and L-methionine which is R, a consequence of the priority mles for systematic descriptors of conhguration (see Section 3.4.10). 

All the molecules in a DNA-encoded library are selected simultaneously. As shown in Ensemble Discovery and GSK s data analyses, a comprehensive view of SAR can be rapidly generated from the lines and planes formed in the SAR plot, high priority structural elements can be identified and applied to the next generation of library design, or to the synthesis of discrete compounds. In addition, a clear correlation between related structural elements with binding potency strongly validates the selection itself. 

The comparator is simpler if the priority vectors are not encoded, that is, if one line is assigned to each master, as on the SCSI bus. A common request line is activated each time an arbitration phase starts. As soon as that request has been recognized, no new priority vector is allowed. 

---