PURPOSE: To provide an information storage device for reading out regardless of storage system for a data in an extension memory.

CONSTITUTION: An extension card is connected with a printer by a connetor 101, and a code data is input into the card by the printer to obtain a pattern. The card into which the code dats is input reads out a character pattern corresponding to the code out of a compression character data 106 and extended by an extension circuit 105 to form an ordinary binary pattern and stored in a data domain 103B of DPRAM. When the completion of extension is informed to the printer by the flag operation in a command domain 103 of DPRAM, the pattern is read out of the domain 103B by the printer. Also the pattern can be called out of the printer, compressed and stored.