ATMs are based on a PC embedded at the center of the machine. This PC connects to multiple serial peripherals such as keypads, cameras, printers, cash dispensers, card readers, touch screens, etc., as required by the particular application. This serial connection is made via multiport serial cards or adapters which can provide up to 16 ports each. Low Profile PCI boards are a particularly good choice for these applications, because their small size is advantageous to the often limited space available in a typical ATM. The diagram below depicts an ATM implemented with Quatech's QSCLP-100 four port RS-232 Serial Universal PCI Low Profile Board.