Abstract: An emulator for a single-chip microcomputer comprises a single-chip microcomputer and an emulation memory which are coupled to each other through a common adress/data bus. A counter is coupled to the address/data bus to receive an address information from the microcomputer and adapted to output an address to the memory. The microcomputer operates to supply an address information on the address/data bus immediately after execution of a branch instruction so that the address information is preset in the counter, and in a program fetch operation the microcomputer generates a program fetch signal to the counter so as to cause the counter to output its content to the memory as an address and also to increment its content.