Researches on the technology of high performance microprogrammed control

A new technology of high performance microprogrammed control is proposed: the executing speed of instruction is improved by using the technique of multiple-control-field, and the word length of microinstruction is reduced by using the technique of set-direct-control. The technique of multiple-control-field is to merge N microinstructions for interpreting a machine instruction into one microinstruction containing N control fields. The functions of original N microinstructions with single control field are implemented by accessing control memory only once. So the executing time of microinstruction is no longer depended on the time of accessing control memory. With set-direct-control, all microinstructions are divided into sets, the control field of microinstruction is divided into a set-selecting field and a microcommand field. Each bit in the microcommand field of microinstruction uniquely represents one microoperation in one set of microinstruction, but may represent other microoperation if it is in a different set. It is determined by set-selecting-bit that what microoperations are given in a microinstruction. Reducing word length of microinstruction by multiplex bit among different sets of microinstruction.