Patent ID: 8266418

Claim:
A computer system comprising: a first storage unit for storing a booting-related program including an operating system program and data, and retaining the stored program and data even when a power voltage is not supplied; and a controller for: determining whether a second storage unit is connected to the computer system, the second storage unit being an external apparatus and volatile, performing a booting operation by executing the booting-related program stored in the first storage unit when the second storage unit is not connected to the computer system, determining whether the booting-related program is stored in the second storage unit when the-second storage unit is connected to the computer system, performing the booting operation by executing the booting-related program stored in the first storage unit and after performing the booting operation storing the booting-related program stored in the first storage unit in the second storage unit when the booting-related program is not stored in the second storage unit, performing the booting operation by executing the booting-related program stored in the second storage unit when the booting-related program is stored in the second storage unit, and backing up the booting-related program stored in the second storage unit to the first storage unit when a predefined backup condition is met.