This paper presents development of a web-based visual simulator with communication support and its application to computer architecture education. The simulator written in Java has equipped visualization and communication support for real education. The former is designed to show how a computer works graphically and helps learners to understand basic computer architecture visually. The latter is realized with a built-in e-mail function. It allows learners to send question e-mails with a snapshot of simulator's execution to instructors. They receive such question emails and then redo to verify the execution of learners' simulators. With these supporting equipments, learners and their instructors can share suitable information between their simulators..