The Secretary of State for Defence in Her Britannic Majesty's Government

National Research Development Corporation

John V McCanny

John G McWhirter

Richard A Evans

Kenneth W Wood

Simon C Knowles

Roger F Woods

A processor suitable for recursive computations is arranged to multiply successive input data words by a co-efficient word to produce results. It incorporates multiplier cells connected to form rows and columns. Each row is arranged to multiply a respective input data digit by the co-efficient. It begins with accumulator cells and continues with multiplier cells each arranged to multiply by an individual co-efficient digit and disposed in the row in descending order of digit significance. Columns other than the first column begin with a multiplier cell, and the higher significance columns terminate at respective accumulator cells. Any intervening multiplier cells are arranged in ascending order of multiplier digit significance. The processor employs radix 2 arithmetic. Each accumulator cell employs redundant radix 2 arithmetic, and each adds the highest significance transfer digit output of its row to at least three digits of equal and higher significance output from a preceding row. Operation of the multiplier and accumulator cells generates sum and transfer digits for output down and between columns in the direction of increasing digit significance in the case of transfer digits. An accumulator cell's computed digit of higher significance becomes the respective row's output result digit. Each result digit is recycled in redundant radix 2 form to provide an input data digit for all multiplier cells of a respective row selected in accordance with result digit significance.

Processor suitable for recursive computations

A digital processor performs an N-point convolution or correlation of q-bit coefficients with data words guard band extended to p bits. The processor includes an array of one-bit clock-activated gated full adder cells arranged in N rows and q columns. Each cell is arranged to input data, carry and cumulative sum bits and to output the data bit and new carry and cumulative sum bits corresponding to the product of the input data bit with a respective stationary coefficient bit. The output carry bit is recirculated on the respective cell. Cumulative sum generation is cascaded down array columns. Data moves along each row and thence to the next lower row via a delay device providing a delay appropriate for correct partial product formation. Data is input bit and word serially to a first row cell and thereafter moves along successive rows progressively further down the array. Sums of partial products output by the array are accumulated according to bit significance by an accumulator device arranged to accumulate successive convolution or correlation results in different adding device. This avoids erroneous addition of contributions to different results. The array is cascadable to provide larger processors. Cascaded arrays may be arranged to be fault tolerant, and a faulty array may be bypassed without operating speed penalties arising from bypass lines.

Digital processor for convolution and correlation

A bit-slice digital processor for performing an N-point correlation or convolution of N single-bit coefficients with a bit parallel, word serial, bit-staggered stream of M bit data words. The processor includes an N row, M column array of one-bit gated full adders with rows extended by half adders to accommodate word growth. Intercell connections incorporating clock activated latches provide for data and result flow unidirectionally down columns, one at twice the rate of the other. Carries and coefficients move unidirectionally along array rows at the faster (data or result) rate. Complex computations are executed by arrays of processors each with output delaying means and an adder to sum separate processor contributions. The processor may include data and result bypass connections subdivided by clocked latches for bypassing without operating speed penalties, as required for fault-tolerant processor array construction.

Bit-slice digital processor for correlation and convolution

A digital data processor is provided to multiply data elements by coefficients. It includes a systolic array of cells consisting of nearest neighbor connected gated full adders. The cells multiply data bits received from laterally adjacent cells and subsequently pass them on. The product is added to a cumulative sum bit from a cell above and to a carry bit recirculated from an earlier computation. The output is passed to a cell below, and a new carry bit is recirculated for addition in a subsequent computation. Data and coefficients are input in counterflow to opposite sides of the array. An adder tree accumulates non-simultaneously computed contributions to individual output terms. The tree incorporates a delay and switches arranged to implement or bypass the delay according to earlier or later computation of a contribution. By virtue of this accumulation, the processor provides reduced cell redundancy compared to the prior art.

Digital data processor for multiplying data by a coefficient set

A digital data processor for matrix/matrix multiplication includes a systolic array of nearest neighbor connected gated full adders. The adders are arranged to multiply two input data bits and to add their product to an input cumulative sum bit and a carry bit from a lower order bit computation. The result and input data bits are output to respective neighboring cells, a new carry bit being recirculated for later addition to a higher order bit computation. Column elements of one matrix and row elements of the other are input to either side of the array bit-serially, least significant bit leading, for mutual counterpropagation therethrough with a cumulative time delay between input of adjacent columns or rows. Bit-level matrix interactions for product matrix computation occur at individual cells. Pairs of intercalated adder trees are connected switchably to the array to accumulate bit-level contributions to product matrix elements.

Pipelined systolic array for matrix-matrix multiplication

The invention provides a digital data processor which has been systemetized down to bit level. The processor includes a regular array of identical processing cells which perform a logic operation on incoming bits. The cells repeatedly perform a cell operation under the control of clocks which govern the inputting to and outputting from the cell of data bits. Each bit takes part in a maximum of one cell operation in one repetition of the clock having the highest repetition frequency. Processing cell arrays for dealing with larger numbers may be readily built up from smaller arrays used for smaller numbers. Having obtained a fully working design for one type of processing cell, the full array consisting of a plurality of cells is proven.

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Malvern, United Kingdom

John V McCanny