That depends on the CSD, every time you use your CD-i player for a specific function, the CSD is over written, if the next time, the battery is dead and the CSD can't be updated anymore, that's a specific state your cd-i player will be in and it determines partly how it will react. That's why every player reacts differently when the timekeeper is dead and there are so many different problems: These batteries go out on a random time.
According to the Green Book, every CD-i player should provide some way to permanently store at least 8 KB of data. In most players, this storage space is implemented as battery-powered NV-RAM (Non-volatile Random Access Memory). The data is kept in this memory when the player is turned off or unplugged from power. NV-RAM can be used by an application to store high scores from games, personal presets, Favourite Track selections for Audio-CDs, Favourite Picture Selections for Photo-CDs, preferred language settings, etc. NV-RAM is also used by the system to store the CSD
Every CD-i player has a piece of non-volatile storage memory (NV-RAM) that is at least 8 KB in size. This contenst of this memory are kept when the player is turned off. Although this doesn't seem much, it allows for powerful storage options, such as games scores, test results, names, preferred language settings, etc. The NV-RAM is also used by the system to store the CSD in an ASCII file called 'csd'.
When a CD-i player is turned on, the CD-RTOS kernel is initialized. One of the startup routines includes the creation of the CSD, which stands for Configuration Status Descriptor. The CSD contains information about a certain CD-i system, such as the amount of NV-RAM available, which kind of pointing device is connected, the version of CD-RTOS used, but also whether a floppy disk drive is available, if a printer is connected, etc. All of these variables are stored per device type on one line of the CSD, which are defined in the Green Book. Each of these device type settings are called DSDs, which stands for Device Status Descriptor (and not Direct Stream Digital as for Super Audio-CD!). Each time the player is turned on or reset (which happens when you eject a disc or exit from a program), the CSD is recompiled. Any newly attached devices will therefore only be recognized and initialized after a reset.
The CSD can be read by an application program to gather information about a certain CD-i player. For example to load a PAL or NTSC optimized version of the program, to offer storage capabilities when a floppydisk drive is available, to know the seek times of the CD drive, or to know the size of the NV-RAM to show the correct usage percentages when displaying the used space of a certain file.
Note that even though the CSD is stored in NV-RAM, the file ‘csd’ is not shown in the “Memory” screen of the player shell. Since this file is critical to the system’s operation, it may not be deleted by the user.
[Thanks, Matt Tyrell, Jorg Kennis]