dvuos - An ATM is typically made up of the following devices:
1. CPU (to control the user interface and transaction devices)
2. Magnetic and/or Chip card reader (to identify the customer)
3. PIN Pad (similar in layout to a Touch tone or Calculator keypad), often manufactured as part of a secure enclosure.
4. Secure cryptoprocessor, generally within a secure enclosure.
5. Display (used by the customer for performing the transaction)
6. Function key buttons (usually close to the display) or a Touchscreen (used to select the various aspects of the transaction)
7. Record Printer (to provide the customer with a record of their transaction)
8. Vault (to store the parts of the machinery requiring restricted access)
9. Housing (for aesthetics and to attach signage to)
Recently, due to heavier computing demands and the falling price of computer-like architectures, ATMs have moved away from custom hardware architectures using microcontrollers and/or application-specific integrated circuits to adopting the hardware architecture of a personal computer, such as, USB connections for peripherals, ethernet and IP communications, and use personal computer operating systems. Although it is undoubtedly cheaper to use commercial off-the-shelf hardware, it does make ATMs potentially vulnerable to the same sort of problems exhibited by conventional computers.(wiki)