The main contributions of this thesis are presenting a UCM & SDL based method to model software requirement,discussing the process in detail and describing the requirements of a small real-time system (Automated Teller Machine,ATM).

• 本文主要贡献在于定义了一个基于UCM和SDL的软件需求描述模型，讨论了整个建模过程，并基于该方法描述了自动柜员机系统需求。