Externally visual attributes, here in computer science, mean the way a system is visible to the logic of programs (not the human eyes!). Organization of computer system is the way of practical implementation which results in realization of architectural specifications of a computer system. In more general language, Architecture of computer system can be considered as a catalog of tools available for any operator using the system, while Organization will be the way the system is structured so that all those cataloged tools can be used, and that in an efficient fashion.
This study material App lists 125 topics with detailed notes, diagrams, equations, formulas & course material, the topics are listed in 5 chapters. Computer system Architecture & Organization is part of computer science, software engineering education courses and information technology degree programs of various universities.