A computer system includes an information processing apparatus configured to incorporate a SCSI (Small Computer System Interface) command into a CBW (Command Block Wrapper), and transmits the CBW based on USB (Universal Serial Bus) protocol; and a peripheral apparatus configured to receive the CBW transmitted from the information processing apparatus, and transmit a value of a predetermined register indicating a state of a GPIO (general purpose input/output) interface to the information processing apparatus, when the SCSI command is a predetermined SCSI command. The information processing apparatus may issue the SCSI command based on an application program. The peripheral apparatus carries out a process corresponding to the SCSI command when the SCSI command is not the predetermined SCSI command.