The implementation of a user-extensible system on a dynamically microprogrammable computer

On a dynamically user-microprogrammable computer the user can tailor the machine to his needs by constructing microprogrammed routines and adding them to the system. If these routines are recognized by the assembler, then using them is no different from using any other basic machine instruction of the computer. The base machine is thus extended. The design and implementation of such a user-extensible system is described. It consists of 2 main parts: a pager which manages a virtual memory for the writable control storage and a user-extensible assembler which accepts microprogrammed routine into the virtual control memory and makes this an integral part of the system.