Processing element VHDL design

The TNP is a simple architecture but consists of many elements. Each element is itself quite complex. This makes it difficult to describe clearly the whole design in a way that will be helpful for the reader. The aim of this design is to  

The focus of the design will therefore be one element of the TNP - the PE architecture. All the elements of this except two will be considered in the design. First, the multiplier is simply a larger version of the parallel multiplier designed in Chapter 6. It should be clear from this earlier version how to create the required structure and so this is left for the reader to complete. Second, the logic to implement the 8-bit radix has not been constructed (section 8.4.4). This helps to simplify the design of the adder. 

TRAN RI,Sln TRAN SOutRI TAG I READ NUL R MemExt,RI ADD R3.R4.R2 TRAN R4.R3 CADD Wptr.Wptr.One CSUB Count I,Count I,One LOOPNZ Iptr.Loop I. Count  

This is instantiated in the top level of the design but the code itself has not been created. The 16 x 16 parallel multiplier is a larger version of the one contained in Chapter 6. Additionally, the multiplier has a rounding capability, overflow and saturation detection. Its design would be a useful exercise for the reader (excluding these features). Be aware, however, of die size of this circuit. One reason that it is omitted here is the length of time the circuit would take to S3mthesize and the physical size of the schematic that would be produced if the result was to be included in this book. 

The adder itself is a procedure called RC ADDER contained in the package ARITH UTILS. This is accessed as usual through a Use clause. 

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This chapter has been a case study of the processing element architecture of the toroidal neural processor. The simple aim has been to present a complete design that incorporates a wide range of the VHDL constructs and synthesis ideas and issues that were introduced in the earlier chapters. It is hoped that the reader will perform some of the suggested exercises linked to this case study and discussed in the text. 

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