Transaction processing systems deal with the retrieval and modification of related business transactions in real-time. They are used for functions like data access, intercomputer communications, and user interface design. Examples include IBM's Transaction Processing Facility and HP's NonStop System.
Office automation systems process, store, and transmit electronic messages and documents. They are used for tasks like word processing, payroll automation, and replacing manual office methods. Examples are automatic teller machines and Microsoft Office applications.
Knowledge work systems have specialized tools for graphics, analysis, and document management. They support applications like CAD for engineering firms. Examples are CAD software, virtual reality systems, and financial sector investment workstations.