bar codes

5-22 — elektor may 1981 bar codes putting data behind bars Hard luck! A "bar code" is not the key to the door of a public house, or even the code of conduct to follow with lady drinkers. In fact you"ve probably noticed it in the form of a new-fangled price tag covered in a strange pattern of black bars and white spaces. Most modern super- markets use them, as it saves the cashier the trouble of looking up and typing the price of each item. A can of beans, along with its bar code, is merely brushed against a sensor and Hey Presto! The price appears on the cashdesk display. But have you ever wondered what is "behind" those bars and blanks, what could be the point of such patterns and what other uses they could have? If so, read on and find out! A closer look reveals that the bars are spaced very irregularly. Perhaps that could mean something too? When various price tags are compared, the mind really starts to boggle, for even the number of bars may vary between one manufacture and...