Terminal symbol computer science

Graphical terminals[ edit ] A graphical terminal can display images as well as text.

In Process Mapping, delays are Terminal symbol computer science important as they may result in adding to the cost of the product or simply delaying its production.

In order to overcome this, special libraries such as curses have been created, together with terminal description databases, such as Termcap and Terminfo.

Consider a grammar defined by two rules. The flow reference symbol acts as a placeholder for the flow area sequence in the chart in every situation in which it is repeated. Entry point documents the place within the master flowchart where the process deviates into a subroutine.

Annotations provide helpful comments or explanations, e. Data shape indicates that information is coming into the process from outside, or leaving the process. Vector-mode displays were historically important but are no longer used. Context-free languages are the theoretical basis for the syntax of most programming languages.

Step represents a single step within a process, and usually contains the name of a specific action.

Data, Document, Decision, or Process. On-page reference indicates that the next or previous step is somewhere else on the flowchart. Start points indicates the starting of a process.

Most terminals today are graphical, that is, they can show images on the screen. Programs such as Telix and Minicom control a modem and the local terminal to let the user interact with remote servers.

Even more advanced interactivity is provided with full-screen applications. The fundamental type of application running on a text terminal is a command line interpreter or shellwhich prompts for commands from the user and executes each command after a press of Enter.

For an application, the simplest way to use a terminal is to simply write and read text strings to and from it sequentially.

Computer terminal

The terminal emulators on most Unix-like systems, such as, for example, gnome-terminalqterminal, xtermterminal. In the past, before the widespread use of local area networking and broadband internet access, many computers would use a serial access program to communicate with other computers via telephone line or serial device.

Standard Flowchart Symbols and Their Usage

Those applications completely control the screen layout; also they respond to key-pressing immediately. This is very helpful for various interactive command line interpreters. The System console is a text terminal used to operate a computer. Dec Terminal was one of the first terminal programs for the popular Altair.

Possibly because of this the standard disappeared without trace. A text editor occupies the full area of display, displays one or more text documents, and allows the user to edit the documents.

Some Unix-like operating systems such as Linux and FreeBSD have virtual consoles to provide several text terminals on a single computer. In this mode, the terminal provides a local line editing function, and sends an entire input line, after it has been locally edited, when the user presses a return key.

Information is presented as an array of pre-selected formed characters. In unix-like operating systems, there are several character special files that correspond to available text terminals.

A typical text terminal produces input and displays output and errors Nano text editor running in the xterm terminal emulator See also: In fact, the language defined by a grammar is precisely the set of terminal strings that can be so derived.

The electronic demands of refreshing display memory meant that graphic terminals were developed much later than text terminals, and initially cost much more.

In the early s an industry consortium attempted to define a standard, AlphaWindowsthat would allow a single CRT screen to implement multiple windows, each of which was to behave as a distinct terminal.

Terminal and nonterminal symbols

For more complex operations, the programs can use terminal specific ioctl system calls. Decision point indicates a sequence in the process at which the end user chooses an option, i. File symbols represent those data elements that exist independently of navigational properties outside of that page, e.

Applying the rules recursively to a source string of symbols will usually terminate in a final output string consisting only of terminal symbols. For many interactive applications this is not sufficient.BSON | terminal and non-terminal.

Ask Question. e.g. a literal character or digit (but not necessarily as it depends on the grammar), a non-terminal symbol is a symbol that can be reduced further by the production rules (the rules that define the grammar) Theoretical Computer Science; Physics; Chemistry; Biology; Computer Science.

Mar 09,  · The DEC VT, a widely emulated computer terminal A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system.

Early terminals were inexpensive devices but very slow compared to punched cards or paper tape for. A typical flowchart from older Computer Science textbooks may have the following kinds of symbols: Start and And, Process, Terminal points.

indicates the ending points of a process. The flow reference symbol acts as a placeholder for the flow area sequence in the chart in every situation in which it is repeated.

Flow area is used as a. Laboratory for Computer Science Massachusetts Institute of Technology. Parse Tables (Review) ACTION Goto • Transition to another state using a terminal symbol is a shift to that state (shift to sn) Computer Language Engineering.

Computer Science Meta Can a CFG end have a non-terminal symbol in the middle of it? Also, technically speaking, recursively enumerable and noncontracting grammars don't really make a distinction between terminal and nonterminal symbols, and the LHS in Type 0 grammars cannot be empty.

Computer Science Meta Is the empty string a terminal symbol? And A,B and C are non-terminal symbols, B and C are different from S and a is a terminal symbol. The definition also states that the last rule can only be present if the language of the grammar accepts the empty string.

Now if $\epsilon$ is a terminal symbol, than this is a.

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Terminal symbol computer science
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