1. A processing system for a portable electronic apparatus comprising: a portable electronic apparatus handling apparatus for outputting a first instruction including each field of an operation code, a data string, and a data length and a second instruction including each field of an operation code which is indicative of continuous processing, and a data string; and a portable electronic apparatus, selectively connected to said portable electronic apparatus handling apparatus, for receiving first and second instructions and for performing processings corresponding to said instructions, said data length being equal to or longer than the data length of the data string included in said instructions, and said portable electronic apparatus, which comprises a memory for storing said data string and a data remaining amount counter, calculating the remaining amount of said data string from a remaining capacity of said memory and the data length of said first instruction and setting the remaining amount to said data remaining amount counter, whereby, when said remaining amount is "0", said portable electronic apparatus outputs response data indicative of completion of processing for said first instruction to said portable electronic apparatus handling apparatus, and when said remaining amount is not "0", said portable electronic apparatus outputs response data indicative of acceptability of said second instruction to said portable electronic apparatus handling apparatus.