Simulation and modeling - Old Questions

Interactive systems are computer systems characterized by significant amounts of interaction between humans and the computer. Editors, CAD-CAM (Computer Aided Design-Computer Aided Manufacture) systems, and data entry systems are all computer systems involving a high degree of human-computer interaction. Games and simulations are interactive systems. Web browsers and Integrated Development Environments (IDEs) are also examples of very complex interactive systems.

The earliest interactive systems were command line systems, which tightly controlled the interaction between the human and the computer. The user was required to know the commands that might be issued and how the arguments were to be ordered. Both the UNIX operating system and DOS (Disk Operating System) are classic examples. Users were required to enter data in a particular sequence. The options for the output of data were also tightly controlled, and generally limited. Such systems generally put a high demand on the user to remember commands and the syntax for issuing these commands.

An interactive system has the potential for variation and unpredictability in its response, and depending on the context may well be considered more in terms of a composition or structured improvisation rather than an instrument.