PURPOSE: To realize an organic function required for read of a book by providing a variable period clock generator for automatic page turning where the period can be specified from the external and stored contents are kept even at the time of power-off.

CONSTITUTION: Characters in a semiconductor memory card 1 are read out to a read and display part 4 with the address, which is stored in a semiconductor memory card address designating register 2 or is specified from the external, as the initial address, and N characters corresponding to one display picture are collectively displayed as sentences and are temporarily kept displayed. After the time of the period which is stored in a variable period clock generator 3 for automatic page turning or is specified from the external, the fundamental operation is repeated from address N+1. Thus, the random organic function for reading is realized, and consequently, a pocket-sized electronic book consisting of this device is effectively applied to not only paperbacked books but also typed books bulky to carry about.