Components of ER Diagram

A five level pyramid model of different types of Information Systems based on the information processing requirement of different levels in the organization. The first level represents transaction processing systems to process basic data. The second level represents office support systems to process information in office. The third level represents management information systems to process information by managers. The fourth level represents decision support systems to process explicit knowledge. The fifth level represents executive information systems to process tacit knowledge.
"A Computer(-Based) Information System is essentially an IS using computer technology to carry out some or all of its planned tasks. The basic components of computer based information system are:
(1) Hardware - these are the devices like the monitor, processor, printer and keyboard, all of which work together to accept, process, show data and information.
(2) Software - are the programs that allow the hardware to process the data.
(3) Databases - are the gathering of associated files or tables containing related data.
(4) Networks - are a connecting system that allows diverse computers to distribute resources.
(5) Procedures - are the commands for combining the components above to process information and produce the preferred output.
The first four components (hardware, software, database and network) make up what is known as the information technology platform. Information technology workers could then use these components to create information systems that watch over safety measures, risk and the management of data. These actions are known as information technology services." [Information systems. Wikipedia]
This pyramid diagram was redesigned using the ConceptDraw PRO diagramming and vector drawing software from Wikimedia Commons file Five-Level-Pyramid-model.png. [commons.wikimedia.org/ wiki/ File:Five-Level-Pyramid-model.png]
This file is licensed under the Creative Commons Attribution 3.0 Unported license. [creativecommons.org/ licenses/ by/ 3.0/ deed.en]
The triangle chart example "Information systems types" is included in the Pyramid Diagrams solution from the Marketing area of ConceptDraw Solution Park.

The vector stencils library "Telecom equipment" contains 11 hardware clipart icons of telecommunication devices for drawing computer network diagrams and equipment layouts.
"In telecommunication, a communications system is a collection of individual communications networks, transmission systems, relay stations, tributary stations, and data terminal equipment (DTE) usually capable of interconnection and interoperation to form an integrated whole. The components of a communications system serve a common purpose, are technically compatible, use common procedures, respond to controls, and operate in union. Telecommunications is a method of communication." [Communications system. Wikipedia]
"A basic telecommunication system consists of three primary units that are always present in some form: (1) A transmitter that takes information and converts it to a signal. (2) A transmission medium, also called the "physical channel" that carries the signal. ... (3) A receiver that takes the signal from the channel and converts it back into usable information." [Telecommunication. Wikipedia]
The clip art example "Telecom equipment - Vector stencils library" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Telecommunication Network Diagrams solution from the Computer and Networks area of ConceptDraw Solution Park.