2 knw d proccessing takes place in an electical supermarket checkout system & wht t computer do?

Question

2 knw d proccessing takes place in an electical supermarket checkout system & wht t computer do.thnx

Answer 1

When an item is scanned, the laser beam is deflected (using mirrors) to move across the UPC bar code (United Product Code).  The reflections of light and dark on the bar code, are reflected back into the scanner to a light sensor.  The light sensor sees a pattern of light and dark, and sends it to the bar-code decoder circuit, which translates the pattern into numbers.  

These numbers are sent over wires to the computer in the store office, which has a database of all the products sold in the store.  The database software gets the number from the scanner and looks it up in the table.  All the information about that product; the description, price, weight and size if necessary, are all sent back to the terminal (where the clerk just scanned it), and displayed on the screen.  The information is also printed on the receipt.  

The cash register keeps a running total and when the clerk hits the "total" button, the tax is computed and added on, and the total is displayed and printed.  The clerk takes the money, gives the change, and the customer walks out with the items.

In a fully electronic system, the clerk is not present, so the customer must follow the directions on the screen.  In this case, each item is scanned, but the weight of the item is also 'looked up' in the database, and when the customer puts it in the grocery bag, there is a scale that weighs the groceries to make sure that the proper items are there and that nothing is shoplifted.

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