Editing Barcode reader (section)

=== Serial interfaces ===
Early barcode scanners, of all formats, almost universally used the then-common [[RS-232]] serial interface. This was an electrically simple means of connection and the software to access it is also relatively simple, although needing to be written for specific computers and their serial ports.

[[Image:Ps-2-ports.jpg|thumb|right|[[PS/2 connector|PS/2]] keyboard and mouse ports]]
As the [[personal computer|PC]] with its various standard interfaces evolved, barcode readers began to use keyboard serial interfaces. The early "keyboard wedge" hardware plugged in between the [[PS/2 port]] and the keyboard, with characters from the barcode scanner appearing exactly as if they had been typed at the keyboard. Today the term is used more broadly for any device which can be plugged in and contribute to the stream of data coming "from the keyboard". Keyboard wedges plugging in via the [[USB | USB interface]] are readily available. In many cases, a choice of [[USB]] interface types ([[USB HID|HID]], [[USB communications device class|CDC]]) are provided.