PURPOSE: To display a document or a hyper text document by an economically efficient method.

CONSTITUTION: One or plural documents such as books or magagines are stored within a nonvolatile memory 30. When the power source of a device is turned on, the first part of the document is displayed on a display screen 40. When a user desires the other part of the document or all of another document, display on the display screen 40 is switch-operated. Though the operation varies depending on the complexity of the document so that some operation display only the next page of the document and others can execute such a nested hyper text link in which related information included within the same or different documents update only a part of the display screen 40. The document is stored in the nonvolatile memory 30 by the same method as directly refreshing the display screen 40.