Abstract: In performing record retrieval processing, a record retrieval processor forms a two-dimensional distribution graph from a plurality of records stored in a record file on the basis of designated items on the x- and y-axes and displays the distribution graph on a display unit. When a retrieval range is designated on the displayed distribution graph, the record retrieval processor retrieves records within the designated range, reads out records on the basis of key codes of the retrieved records corresponding to the items, and displays the readout records on the display unit.

Abstract: An inexpensive DC power source apparatus is provided which realizes a countermeasure against high frequency and redundant operation for improving reliability by using a simplified circuit construction to thereby reduce the number of parts. An input voltage follow type current controlled boosting chopper and a current feedback type self-running inverter are used in combination, and output voltage stabilization is accomplished by utilizing the voltage stabilizing function of the boosting chopper and current balance during parallel operation is accomplished by self-balance due to an impedance drop in the self-running inverter, thereby realizing the inexpensive power source apparatus in which the number of parts is reduced.

Abstract: A rowwise line of a memory cell array in a semiconductor memory storing a dot image is selected with the aid of a part of an address signal. Data of the selected one rowwise line is considered to be represented in the form of a data matrix array including a plurality of rows and a plurality of columns. One row or one column of the matrix array is designated by the remaining part of the address signal. Dot image data rotated by 90.degree., 180.degree. or 270.degree. relative to the stored image data can be successively read out with the address signal undergoing no more than a regular change.