Microprogrammed processor system having external memory

Abstract

A data processing system including a central processing unit and external memory. The central processing unit has an arithmetic logic unit having first and second inputs and an output for outputting data. The arithmetic logic unit inputs are selectively connected to the outputs of a plurality of addressable registers which registers have inputs connectable to the arithmetic logic unit output for receiving and storing data therefrom. Additionally, the central processing unit has a read only memory capable of storing a plurality of addressable control instructions and having a plurality of outputs for supplying control signals in dependence upon the addressed control instructions and means capable of addressing control instructions stored in the read only memory in a predetermined sequence, or addressing a selected one of said word locations in dependence upon the data outputted from the arithmetic logic unit. The central processing unit, additionally, has a means for carrying signals adapted to be applied to the external memory for addressing the external memory and for storing data therein.