Terminal / microcomputer to mainframe computer layouts

     Today, many businesses still employ a terminal-to-mainframe layout, although the number of these systems in use is not what it used to be. During the 1960s and 1970s, the terminal-to-mainframe layout was in virtually every office, manufacturing, and academic environment. These types of systems are still being
used for inquiry/response applications, interactive applications, and data-entry applications, such as you might find when applying for a new driver’s license at the Department of Motor Vehicles

Using a terminal (or thin client workstation) to perform a text-based input transaction

      The terminal-to-mainframe layouts of the 1960s and 1970s used “dumb” terminals because the end user was doing relatively simple data-entry and retrieval operations, and a workstation with a lot of computing power and storage was not necessary. A computer terminal was a device that was essentially a keyboard and screen with no long-term storage capabilities and little, if any, processing power. Computer terminals were used for entering data into a system, such as a mainframe computer, and then displaying results from the mainframe. Because the terminal did not possess a lot of computing power, the mainframe computer controlled the sending and receiving of data to and from each terminal. This required special types of protocols (sets of rules used by communication devices), and the data was usually transmitted at relatively slow speeds, such as 9600 or 19,200 bits per second (bps).

     During this period, many of the same end users who had terminals on their desks also now found a microcomputer there (and thus had very little room for anything else). In time, terminal-emulation cards were developed, which allowed a microcomputer to imitate the abilities of a computer terminal. As terminal
emulation cards were added to microcomputers, terminals were removed from end users’ desks, and microcomputers began to serve both functions. Now, if users wished, they could download information from the mainframe computer to their microcomputers, perform operations on the data, and then upload the
information to the mainframe. Today, one rarely sees dumb computer terminals. Instead, most users use microcomputers and access the mainframe using either a terminal emulation card, a Web browser and Web interface, Telnet software (more on this in Chapter Ten), or a thin client. A thin client workstation is
similar to a microcomputer but has no hard drive storage.