A computer system and a method of booting a computer system using a solid state drive (SSD) as a main storage device is provided. The method includes mapping an address of a memory included in the SSD to an address used by a central processing unit (CPU) to select a boot code, uploading the boot code of an operating system (OS) stored in a non-volatile memory block included in the SSD to the memory included in the SSD, generating an interrupt signal based on a progress rate of the boot code upload, and performing a boot operation based on the boot code uploaded to the memory included in the SSD in response to the interrupt signal.