peripherals are real devices, such as graphics cards or disks controlled by controller chips on the system board or on cards plugged into it.
外设是一些物理设备，比如说图象卡或者磁盘，它们受控于位于主板或者主板上插槽中的控制芯片。
A LAN is a system of computers and associated peripherals such as Printers that are physically connected by cable within a limited geographical area-typically in an office building or on a college campus.
局域网就是在一个有限的地域范围内，典型的如在办公大楼或校园中，将计算机及相关外设（如打印机）用电缆进行物理连结而组成的一个系统。
