Abstract: An optical disc equipped with a hub having a centering hole into which a spindle shaft of a disc driving mechanism is inserted, wherein a centering hole portion of the hub is provided with a centering hole reinforcing means made of a material excellent in abrasion resistance and smoothness or a member having a central hole is formed of a resin excellent in abrasion resistance and smoothness.

Abstract: A magneto-optical disc recording/reproducing apparatus in which a magneto-optical disc, a disc rotating and driving unit, an optical head device, an external magnetic field generating unit and a controlling device are contained as one in an outer casing.

Abstract: A recording and/or reproducing method for using an optical disc in the recording or reproduction data on or from the optical disc in predetermined data-length units. In a recording operation, the recording and/or reproducing method includes the step of dividing data read from the optical disc in the predetermined sector length, rewriting inputted data into the desired sector which is divided from the predetermined data-length inputs and recording the data including the rewritten sector on the optical disc in the predetermined data-length units. In a reproducing operation, the recording and/or reproducing method includes the step of reading the data having from the optical disc in the predetermined data-length units, dividing the data read from the optical disc in the predetermined data-length units into the predetermined sector length and transferring data of the reproduced desired sector as output data.

Abstract: A multi-port memory with a memory array having a plurality of memory cells arranged in a matrix fashion. The memory array includes first signal lines for selecting rows of the plurality of memory cells. The memory array further includes second signal lines for selecting columns of the plurality of memory cells. The multi-port memory further includes a first decoder for generating select signals for selecting the first signal lines. The multi-port memory further includes a plurality of input or output ports connected to the second signal lines. The multi-port memory further includes a second decoder for use in common for the plurality of input/output ports and for generating select signals for selecting the second signal lines, wherein the select signals for selecting second signal lines to connect to the plurality of input/output ports the second signal lines are shifted one by one, respectively. The multi-port memory may be used with an interpolation circuit in a digital interpolation apparatus.

Abstract: An optical disc for use as a compact disc, an optical video disc, or the like has a disc substrate of a light-transmissive material such as polycarbonate, PMMA, or the like. The disc substrate has a pattern of pits and lands formed as representing an information signal on at least one surface thereof. A thin reflective layer of a-corrosion-resistant metallic material such as an alloy of Fe, Ni, and Co is deposited on the disc substrate over the pattern of pits and lands. The optical disc is relatively inexpensive to manufacture as no protective layer needs to be deposited on the reflective layer and is also highly resistant to loss of performance with aging because the reflective layer is made of a corrosion-resistant metallic material.

Abstract: Methods for generating free curves and sculptured surfaces illustratively for use with a computer aided design/computer aided manufacturing (CAD/CAM) apparatus whereby Bezier curves and surfaces are readily generated with reference to point sequences, point groups and surfaces. In operation, a starting point and an end point for a sequence of points are set as nodes, and a free curve is temporarily established thereby. Then control points are repeatedly established to minimize the shortest distances between the points in the sequence and the free curve. By use of the coordinates of a plurality of points, the shortest distance is found between each of these points and a reference patch. The internal control points are set so as to minimize the total sum of these shortest distances.

Abstract: Q- or P-sequence error correction is suitable for correcting errors of data stored in a CD-ROM. Errors of data are corrected using a 2-word parity code added to the data and input pointers that have been set for the words that are presumed to be subjected to errors. Output pointers are set for respective words of data which are presumed not to be error-corrected completely.

Abstract: A CD-I player for reproducing from a CD-I disc 2 both recorded audio information but and recorded video information and the like is recorded, is disclosed. The frequency of the clock signals of a MCPU 61 for executing a program is changed by a frequency divider 67 and a changeover switch 69. So that the speed of program execution may be changed according to the particular application or usage of the player or the liking of the user.