Abstract-An important problem in teaching courses in computer architecture and organization is to find a way to help students to make a cognitive leap from the blackboard description of a computer system to its utilization as a programmable device. Computer simulators developed to tackle this problem vary in scope, target architecture, user interface, and support for distance learning. Usually, they include the processor only, lacking the whole-system perspective. The existing simulators mainly focus on the programmer's view of the machine and do not provide the designer's perspective. This paper presents an educational computer system and its Web-based simulator, designed to help teaching and learning computer architecture and organization courses. The educational computer system is designed to cover a broad spectrum of topics taught in lower division courses. It offers a unique environment that exposes students to both the programmer and the designer's perspective of the computer system. The Web-based simulator features an interactive animation of program execution and allows students to navigate through different levels of the educational computer system's hierarchy-starting from the top level with block representation down to the implementation level with standard sequential and combinational logic blocks.