Maintenance

This page lists various changes that might be made to the system. Modifying the various documents to incorporate one or more of these changes would make an interesting exercise for the reader.

Corrective Maintenance

• The careful reader will note that the requirement that "Entries will be made in the log when the ATM is started up and shut down" has not been reflected in any of the diagrams or the code. What changes would be needed to implement this requirement?

Adaptive Maintenance

• Many ATM's have cash dispensers that can handle two different denominations of bills - often $20 and $5 - which allows a user to request cash in any amount that is a multiple of $5. Suppose the cash dispenser in the example (which only handles $20 bills) were replaced with such a dispenser. What changes would be needed to take advantage of the enhanced capabilities of such a dispenser?

Perfective Maintenance

• When the customer's card is retained, an entry should be made in the log to this effect.
• Many ATM's offer the customer additional options beyond the basic four listed here - e.g. making a payment on a loan the customer has from one of the accounts linked to his/her card. What changes would be needed to make it possible for a customer to make a loan payment at the ATM?

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Copyright © 2000, 2001 - Russell C. Bjork. Permission for non-commercial reproduction for educational use is hereby granted; all other rights are reserved.