Our initial design for a machine that serves coffee for 35 cents, with or without sugar and/or creamer was:
With a sample interaction diagram of:
1. After five machines are installed and have been operating for a while, Arnold comes along and says, "I would like to add chicken soup, at twenty-five cents. Change the machine." We add to the machine one more button for chicken soup, and one more container for instant soup powder.
2. Arnold comes back a while later with a brilliant idea. He has heard that some companies use their company badges to directly debit the cost of coffee purchases from their employees' paychecks. Arnold's employees already have badges, so he thinks this should be a simple change. And he hates to be behind the curve. We add to the hardware a badge reader and link to the payroll system.
How do you change your design?
- What's the problem with our old design for interaction between cashbox and front panel?
- How do you change your software design?