A dynamically reconfigurable large-scale multimicroprocessor system capable of operating as one or more independent SIMD (single instruction stream - multiple data stream) machines and/or MIMD (multiple instruction stream - multiple data stream) machines is described. User microprogrammable bipolar bit-slices are used as building locks in the construction of computational and control units. The semi-stack architecture and instruction set of these units are described. Instructions unique to parallel processing are included in the system design. A highly flexible subroutine linkage facility is presented. Methods for analyzing the instruction set are discussed.