ECMA-201

This Ecma Standard specifies the characteristics of 90 mm Optical Disk Cartridges (ODC) with a capacity of 230 Mbytes per Cartridge. The Standard specifies three 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 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 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, Type P-ROM and Type O-ROM are also referred to as “fully rewritable”, “partially embossed” and “fully embossed”, respectively.

This Ecma 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 Ecma 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.