1. A digital computer system having central processor unit and a microcommand memory for controlling the central processor unit, comprising: (a) a main memory having a plurality of central processor unit working registers in at least one workspace; (b) a workspace pointer register for indicating the location of the workspace; (c) workspace cache memory means, corresponding to the plurality of working registers in the workspace, connected to provide digital words to the central processor unit and to bilaterally exchange digital words with the plurality of working registers; (d) indicia means indicating the presence or absence of digital words in the workspace cache memory means; and (e) command means, responsive to the microcommand words from the microcommand memory for transferring the contents of the workspace cache memory means to the workspace in the main memory at the address indicated by the workspace pointer register and for transferring the contents of selected ones of the plurality of working registers to the workspace cache memory.