T 4.9 Disruption of the internal power supply

Use of a mobile IT system, e.g. a laptop, pre-supposes that the system has a power supply unit independent of the mains. Such a unit, which generally uses rechargeable batteries, will usually last for several hours of operation. After that period, sufficient power supply is no longer ensured so the IT system will have to be de-activated or connected to the supply mains. The majority of mobile systems constantly check the supply voltage and indicate any critical voltage drop. If such a message is disregarded, the system may all of a sudden become inoperative, and the results of the latest transactions that are stored only in the main memory, will be lost.