An Operating Systems Vade Mecum

Historical development 11control and surveys the solutions that have been found for these problems.3.6 Interactive multiprogrammingThe next step in the development of operating systems was the introduction of interactivemultiprogramming, shown in Figure 1.6. The principal user-oriented transput devicechanged from cards or tape to the interactive terminal. Instead of packaging all thedata that a program might need before it starts running, the interactive user is able to supplyinput as the program wants it. The data can depend on what the program has producedso far.Interactive computing is sometimes added into an existing batch multiprogrammingenvironment. For example, TSO (‘‘timesharing option’’) was an add-on to theOS/360 operating system. In contrast, batch is sometimes added into an existing interactiveenvironment. Unix installations, for example, often provide a batch service.Interactive computing caused a revolution in the way computers were used.Instead of being treated as number crunchers, they became information manipulators.Interactive text editors allowed users to construct data files online. These files couldrepresent programs, documents, or data. Instead of speaking of a job composed of steps,interactive multiprogramming (also called ‘‘timesharing’’) deals with sessions that lastfrom initial connection (logon) to the point at which that connection is broken (logoff).processesresponsesservice callsprocess interfaceinterruptskerneldevice controldevice interfaceterminalscardsclockdisks printerstapesnetworksuser interfaceother computersFigure 1.6 Interactive multiprogramming