scope:

This International Standard defines the characteristics of 90 mm Optical Disk Cartridges (ODC) with a capacity of 640 Mbytes per Cartridge. The Standard specifies five related, but different implementations of such cartridges, viz.

Type R/W

Provides for data to be written, read and erased many times over the whole recording surface of the disk using the thermo-magnetic and magneto-optical effects.

Type DOW

Provides for data to be written and read many times over the whole recording surface of the disk, using the direct overwrite thermo-magnetic and magneto-optical effects requiring a single external magnetic field.

Type P-ROM

Provides for a part of the disk surface to be embossed by stamping or other means. This part of the disk is read without recourse to the magneto-optical effect. All parts which are not embossed provide for data to meet the requirements of Type R/W.

Type P-DOW

Provides for a part of the disk surface to be embossed by stamping or other means. This part of the disk is read without recourse to the magneto-optical effect. All parts which are not embossed provide for data to meet the requirements of Type DOW.

Type O-ROM

Provides for the whole of the disk surface to be embossed and reproduced by stamping or other means. This type of disk is read without recourse to the magneto-optical effect.

Type R/W and Type DOW are also referred to as "fully rewritable", Type P-ROM and Type P-DOW as "partially embossed" and Type O-ROM as "fully embossed".

For each Type, this International Standard provides for 5 12-byte and 2 04%byte sectors. All sectors on a disk are of the same size.

This International Standard specifies

- the conditions for conformance testing and the Reference Drive;

- the environments in which the cartridges are to be operated and stored;

- the mechanical and physical characteristics of the cartridge, so as to provide mechanical interchangeability between data processing systems;

- the format of the information on the disk, both embossed and user-written; including the physical disposition of the tracks and sectors, the error correction codes, and the modulation method used;

- the characteristics of the embossed information on the disk;

- the magneto-optical characteristics of the disk, enabling processing systems to write data onto the disk;

- the minimum quality of user-written data on the disk, enabling data processing systems to read data from the disk.

This International Standard provides for interchange between optical disk drives. Together with a standard for volume and file structure, it provides for full data interchange between data processing systems.