aw 1) a context data flow diagram and 2) a level-0 diagram that shows the

appropriate details for the point of sales system described below:

Self-checkout system at Big Joes Supermarket uses a scanner to read universal product

codes (UPC). When a customer scans a product, the system reads the code (i.e.,

barcode) of the product and retrieves product information based on data stored in a

product file. The system displays the product summary to the customer. When the

customer provides payment information, the system verifies the payment information

by connecting to an external credit/banking verification system. Purchases made are

stored in a file to be used in printing the receipt. After the purchase has been made a

receipt is produced and given to the customer