[1] The initial Pilot DAP was designed and implemented by Dr Stewart F Reddaway with the aid of David J Hunt and Peter M Flanders at the ICL Stevenage Labs.
Operationally, there was an overhead to transfer computational data into and out of the array, and problems which did not fit the 64×64 matrix imposed additional complexity to handle the boundaries (65×65 was perhaps the worst case!
The design as described in Reddaway's 1973 paper is pretty much that which was implemented in the first commercial version except the facility to supply address bits from the processing elements was removed.
[4] The DAP [IP] was sold off to a venture capital-funded start-up company Active Memory Technology (AMT) which was then taken over by Cambridge Parallel Processors (CPP).
These were more flexible than DAP FORTRAN, in particular they automatically took care of choosing a mapping from user specified matrix and vector bounds to the underlying hardware.