A pocketbook-sized computer with a combined touch-sensitive membrane covering an LCD panel as its main input and output device. The user writes on the screen with a penlike stylus, and the objects drawn are echoed on the screen. It is possible to interpret handwriting by means of character-recognition techniques, to store what is written or drawn as images for later retrieval, or for the screen to display menus and check boxes so that selections may be made with the stylus. Some PDAs, such as the BlackBerry, have small keyboards optimized for easy operation with the thumbs. Applications include calendars, diaries, personal organizer functions, wireless networking, email, and Internet access.