External devices that can read a Personal identification number (PIN) or other information may also be connected to a keyboard (usually called "card readers with PIN pad"). This model works by supplying the integrated circuit on the smart card with electricity and communicating via protocols, thereby enabling the user to read and write to a fixed address on the card.
A barcode is a series of alternating dark and light stripes that are read by an optical scanner. The organization and width of the lines is determined by the bar code protocol selected. There are many different protocols, such as the prevalent Code 39.[3] Sometimes the digits represented by the dark and light bars are also printed to allow people to read the number without an optical reader.
In the 1-to-many mode a user presents biometric data such as a fingerprint or retina scan and the reader then compares the live scan to all the templates stored in the memory. This method is preferred by most end-users, because it eliminates the need to carry ID cards or use PINs. On the other hand, this method is slower, because the reader may have to perform thousands of comparison operations until it finds the match. An important technical characteristic of a 1-to-many reader is the number of comparisons that can be performed in one second, which is considered the maximum time that users can wait at a door without noticing a delay. Currently most 1-to-many readers are capable of performing 2,000–3,000 matching operations per second.
External devices that can read a Personal identification number (PIN) or other information may also be connected to a keyboard (usually called "card readers with PIN pad"). This model works by supplying the integrated circuit on the smart card with electricity and communicating via protocols, thereby enabling the user to read and write to a fixed address on the card.
In the 1-to-1 mode a user must first either present an ID card or enter a PIN. The reader then looks up the template of the corresponding user in the database and compares it with the live scan. The 1-to-1 method is considered more secure and is generally faster as the reader needs to perform only one comparison. Most 1-to-1 biometric readers are "dual-technology" readers: they either have a built-in proximity, smart card or keypad reader, or they have an input for connecting an external card reader.