Still picture display apparatus and external storage device used therein

An external storage device used in association with a still picture display apparatus which displays a still picture containing an arrangement of a predetermined number of characters, each character being constituted by a combination of a predetermined number of dots on a screen of a raster scan monitor, said external storage device comprising:

• a storage device storing character data of the characters;
• and
• a random access storage device storing a plurality of vertical offset data and a plurality of horizontal offset data per one horizontal line, each of said plurality of vertical offset data and each of said horizontal offset data being a vertical offset amount and a horizontal offset amount, respectively, in each of a plurality of horizontally divided portions of said screen of the raster scan monitor;
• said still picture display apparatus including
• a counting device for producing data representing a horizontal position and a vertical position on the raster scan monitor;
• first read circuits for reading one of the plurality of vertical offset data and one of the plurality of horizontal offset data when a corresponding one of said plurality of horizontally divided portions of said screen is to be scanned;
• and
• second read circuits for reading the character data from said first storage means, based on the vertical offset data and the horizontal offset data read by said first read circuits and a horizontal position and a vertical position on said raster scan monitor from the counting device to apply the character data to said raster scan monitor,
• wherein said random access storage device includes a readable/writable memory, and said apparatus further comprising vertical offset data write circuits for writing the vertical offset data corresponding to each character into said memory, and horizontal offset data write circuits for writing the horizontal offset data into said memory, and
• wherein said vertical offset data write circuits include vertical offset data changing circuits for changing and writing the vertical offset data per each frame of said raster scan monitor, so that a vertical scrolling is performed in at least one of said plurality of horizontally divided portions of said screen of said raster scan monitor.