Universal Media Disc

Description

The Universal Media Disc (UMD) is an optical disc medium developed by Sony for use on the PlayStation Portable. It can hold up to 1.8 gigabytes of data. It is considered the first optical disc format to be used for a handheld video game system.
Source

Logo

ECMA

This Ecma Standard specifies the mechanical, physical and optical characteristics of a 60 mm, read-only ODC having a maximum capacity of 1,8 Gbytes. It specifies the physical format, the quality of the recorded signals, the format of the data and its modulation method, thereby allowing for information interchange by means of such ODCs.

This Ecma standard specifies two types of ODCs, Type A and Type B.

Type A: Single layer disk with maximum recorded capacity of 0,9 G-bytes
Type B: Dual layer disk with maximum recorded capacity of 1,8 G-bytes

Information interchange between systems also requires, at a minimum, agreement between the interchange parties upon the interchange code(s) and the specifications of the structure and labeling of the information on the interchanged ODCs.
Source