An automatic teller machine, or ATM, functions in much the same way as a personal computer. It has hardware, software, a modem and a user interface, which allows a cardholder to control its actions. Unlike a PC, however, also has an internal storage unit and a system of robotics that receives electronic commands and relays cash from its safe to the user. These parts combine to form the ATM, which allows cardholders worldwide to process deposits, withdrawals and inquiries without ever entering a bank.
The card reader interprets the information encoded in the magnetic strip on the back of an ATM card. Once a user swipes his card, the reader relays that information to an internal computer, which then connects to the cardholder's bank. An ATM may use a dip card reader, which requires the user to insert his card into a slot, or a swipe card reader.
The screen provides an interface between the ATM's internal computer and the cardholder. Each time the cardholder inputs data, the screen's display changes to show further options, directions or information. Like household computer screens, they can be CRT (cathode ray tube) or LCD displays and may be black-and-white or color.
The keypad allows the cardholder to make selections and input information. The number keys are to input the card's PIN. This PIN is a code that is unique to the card and identifies the user as the legitimate cardholder. Other buttons allow the user to select options, clear entries or cancel a request.
Other External Parts
ATMs have a cash dispenser below the keypad where bills come out. A receipt printer generates a record of the transaction and then ejects it through the receipt slot. Some ATMs also have a deposit slot where the user can insert cash or checks to be credited to his account. ATMs also have a speaker that allow the buttons to beep. This helps the user know when she has pressed the button hard enough to register with the machine.
Inside the ATM is a computer loaded with software and a modem, which allows the machine to connect to the data terminal. There is also a receipt printer and a vault. Inside the vault are multiple cash boxes, a reject box which holds defective currency, a conveyer belt which moves the money, a power supply and a control board.