The
earliest, and still the cheapest, barcode scanners are built from a
fixed light and a single photosensor that is manually "scrubbed" across
the barcode.
Barcode scanners can be classified into three
categories based on their connection to the computer. The older type is
the RS-232 barcode scanner. This type requires special programming for
transferring the input data to the application program....
"Keyboard interface scanners" connect to a computer using a PS/2 or AT
keyboard–compatible adaptor cable. The barcode's data is sent to the
computer as if it had been typed on the keyboard.
Like the keyboard
interface scanner, USB scanners are easy to install and do not need
custom code for transferring input data to the application program.
By SAm with 2 comments