1. brainstorm
   1. hardware
      1. Power
         1. If system loses power, electronic money will be useless.
      2. Network
         1. If network broken, whole system would not work.
      3. Component
         1. Components may not be produced in the future.
   2. software
      1. OS Change
         1. System may not install on the future operation system.
      2. Closed System
         1. Programmer could not revise system because commercial system is compiled.
            1. 分支主題 1
      3. Software interdependency
         1. Every programmer would develop system by their own style. So different systems maybe could not interact with each other.
2. Internet Research
   1. Give at least 5 website urls
   2. concept
      1. Reliability, Availability and Serviceability (RAS)
   3. standards
      1. IEEE Standards Association
   4. open source
      1. Linux.org
   5. sustainable power
      1. How to Run a Computer on Solar Power
   6. customize components
      1. 3D printing - wikipedia