Design ATM Machine

Functional Requirements:

• Users can authenticate using a bank card and PIN.
• Users can view account balance.
• Users can withdraw cash, subject to daily and per-transaction limits.
• Users can deposit cash.
• Users can view recent transaction history.
• Users can change their PIN.
• Admins can refill cash and check ATM status.
• All transactions and admin actions are logged for audit.

Non-Functional Requirements:

• Each transaction should complete within a few seconds under normal conditions.
• System should be secure, with encrypted communication and PIN storage.
• System should be reliable, with minimal downtime.
• System should be able to support multiple ATMs operating concurrently.
• Data integrity must be maintained for all financial transactions.