basically i want to ask question about configurable addressing scheme for LAN interface hardware. i have read about it from a book, some main points are given by

a configurable addressing scheme provides a mechanism that a customer can use to set a physical address.The mechanism can be manual (the switches that must be set when the interface is first installed).or an electronic memory such as an EPROM that can be downloded from the computer(what does this means). Most hardware needs to be configured only once- configuration is usually done when the hardware is first installed.

Question:Suppose a network administrator configures the LAN interface hardware (assigns the address) when he installs it. Now later on if he needs to change the physical address of the device can he change it? Or in this addressing scheme the hardware can only be configured once and we can not reconfigure it later on.