TRANQUIL: a language for an array processing computer

Abstract

TRANQUIL is the algorithmic language which will be used to write programs for ILLIAC IV, a parallel computer which has been described by Barnes et al. ILLIAC IV is designed to be an array of 256 coupled processing elements (PE's) arranged in four quadrants in each of which the 64 PE's are driven by instructions emanating from a single control unit (CU). Each of the 256 PE's is to have 2048 words of 64 bit semiconductor memory with a 250 nanosecond cycle time and an instruction set which includes floating point arithmetic on both 64 bit and 32 bit operands with options for rounding and normalization, 8 bit byte operations, and a wide range of tests due to the use of addressable registers and a full set of comparisons. The PE's differ from conventional digital computers in two main ways. Firstly, each is capable of communicating data to its four neighboring PE's in the array by means of routing instructions. Secondly, each PE is able to set its own mode registers, thus effectively enabling or disabling itself for the transmission of data or the execution of instructions from its CU.