Microprogram controller having fixed-instruction generator and microprogram memory

摘要

A microprogram controller in which the initiation of a string of microinstructions is advanced to enhance the in­struction execution speed in total comprises a memory for storing microinstructions, a first register for temporarily storing address information for accessing said memory, a second register for temporarily storing a microinstruction to be executed, an execution unit for receiving and executing a microinstruction from said second register, a generator for generating a leading microinstruction of a predetermined microinstruction string consisting of at least two microinstructions, a selector coupled to said memory and said generator for selecting one of a micro­instruction read out of said memory and said leading micro­instruction generated from said generator and for supplying the selected microinstruction to said second register, and means for causing said selector to select said leading microinstruction before a microinstruction is read out of said memory by said first register being loaded with pre­determined address information and thereafter for causing said selector to select the microinstruction read out of said memory.