A computer system includes a computer and a peripheral device. A communication cable, used to connect the peripheral device to the computer, has a first cable, a second cable and a patch unit. The first cable encloses a set of power lines and a set of data lines, and the second cable encloses a set of data lines. The patch unit includes a socket with first and second contacts. In the patch unit, the sets of data lines of the first and second cables are connected. One of the power lines is connected to the first contact, and another of the power lines is connected to the second contact. The first cable connects the patch unit with the peripheral device, and the second cable connects the patch unit with the computer. When power is applied from an external source to the first and second contacts, the power is supplied from the first and second contacts to the peripheral device.