Variable Field-Length Data Manipulation in a Fixed Word-Length Memory

Many medium-scale electronic computers currently are being designed to cater to scientific and business data-processing problems. Efficiency of floating point computation for scientific problems usually favors a fixed-word format and a word-oriented memory, so that a complete floating-point operand may be read out of or stored in memory in parallel. The logical processing of strings of characters not starting or ending on a word boundary, or the arithmetic processing of variable field-length fixed-point operands, are penalized. The penalty is the result of time-consuming combinations of masking and/or shifting which must be programmed before or after processing and before results can be stored. The purpose of this report is to describe several representative memory-access systems that avoid the housekeeping necessary for processing variable-length operands in a fixed word-length machine and to evaluate their relative efficiencies.