This is an example of context diagram there is also diagram level one but it is not shown in the example

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This is an example of context diagram there is also diagram level one but it is not shown in the example

Constructing Data Flow Diagrams: ATM Machine To start an ATM Withdrawal: • A card is inserted in the slot by the user, and the PIN (personal identification number) is entered. • The ATM reads information from the card, in particular, the card number and the expiry date, and accepts the PIN from the keyboard input. • The card is verified for expiry date, and then if valid, the card number and the PIN are sent to the bank for card validation by communication circuit. • The bank either sends confirmation or refusal. If confirmation is received, the user is invited to enter a transaction type. • Assuming that the transaction is a withdrawal of cash, one more validation is performed by the bank to check that the amount nominated is below or equal to the daily limit for withdrawals of 1000 AED, that the user’s weekly withdrawals do not exceed the weekly limit of 5000 AED, and that the account balance is in credit to cover the withdrawal. • If all these are OK the card is returned, the money is dispensed, and the withdrawal receipt is printed, with the date, account number, withdrawal amount and account balance. • The bank’s account records are updated to reflect the transaction. Based on the previous scenario, create the following:

a) Create a Context diagram

b) Create level zero DFD diagram

c) Select one process from level zero and develop it into level 1 diagram.

The correct answer and explanation is :

Here is the Context Diagram and Level Zero Data Flow Diagram (DFD) for the ATM Withdrawal System based on the provided scenario. I will also expand one process from Level Zero into a Level One DFD and provide an explanation.

Context Diagram (ATM System)

The Context Diagram represents the system at a high level, showing its interaction with external entities. The ATM System is the central process, interacting with:

  1. User (Customer) – Inserts the card, enters the PIN, requests a transaction, and receives cash and a receipt.
  2. Bank System – Verifies the card, validates withdrawal limits, updates account balances, and confirms transactions.

Level Zero DFD (ATM Withdrawal Process)

The Level Zero DFD breaks the ATM system into several processes:

  1. Insert Card & Enter PIN: The user inputs their card and PIN.
  2. Verify Card & PIN: The ATM verifies the card information with the bank.
  3. Select Transaction: The user selects a withdrawal.
  4. Validate Withdrawal: The ATM checks limits and account balance via the bank.
  5. Dispense Cash & Print Receipt: If validated, the ATM dispenses money and prints a receipt.
  6. Update Bank Records: The bank updates the user’s account.

Level One DFD (Expanding “Validate Withdrawal”)

The “Validate Withdrawal” process involves:

  1. Checking if the withdrawal is below the daily limit (1000 AED).
  2. Checking if the weekly withdrawal limit (5000 AED) is not exceeded.
  3. Ensuring the account balance is sufficient.
  4. Sending approval or rejection to the ATM.

Now, I will generate the DFD diagrams as images for you.

Here is the Context Diagram for the ATM Withdrawal System. Next, I will generate the Level Zero DFD diagram.

Here is the Level Zero Data Flow Diagram (DFD) for the ATM Withdrawal System. Next, I will generate the Level One DFD by expanding the “Validate Withdrawal” process.

Here is the Level One Data Flow Diagram (DFD) for the “Validate Withdrawal” process. Now, I will provide an explanation of the diagrams.

Explanation of the Diagrams

Context Diagram

The Context Diagram provides a high-level overview of the ATM system, showing external entities that interact with it:

  1. The User inserts their card, enters a PIN, and selects a withdrawal.
  2. The ATM System communicates with the Bank System for validation and transaction processing.
  3. The bank either approves or denies the transaction.
  4. If approved, the ATM dispenses cash, prints a receipt, and updates the bank records.

Level Zero DFD

This diagram breaks the ATM system into multiple processes:

  1. User Input (Card & PIN Entry): The user inserts the card and enters the PIN.
  2. Card Verification: The ATM checks the card details with the bank.
  3. Transaction Selection: The user chooses the type of transaction (withdrawal).
  4. Withdrawal Validation: The ATM checks daily limits, weekly limits, and balance via the bank.
  5. Transaction Execution: If valid, cash is dispensed, and a receipt is printed.
  6. Bank Records Update: The bank updates the user’s account balance.

Level One DFD – “Validate Withdrawal”

This diagram expands the Validate Withdrawal process:

  1. The ATM checks if the daily withdrawal limit (1000 AED) is exceeded.
  2. If the daily limit is okay, the ATM checks if the weekly withdrawal limit (5000 AED) is exceeded.
  3. If the weekly limit is also okay, the account balance is checked to ensure sufficient funds.
  4. The ATM then sends a request to the bank for final validation.
  5. The bank approves or denies the request.
  6. The ATM notifies the user of the result.

This breakdown ensures that security and withdrawal limits are enforced before completing the transaction.

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