The system console , computer console , root console , operator ‘s console , or simply console is the text entry and display device for system administration messages, PARTICULARLY Those from the BIOS or boot loader , the kernel , from the init system and from the system logger . It is a physical device of a keyboard and a screen, and is traditionally a terminal text , but may also be a graphical terminal . System consoles are generalized to computer terminals, which are abstracted by virtual consoles and terminal emulators . Today communication with system consoles is done abstractly, via the standard streams ( stdin , stdout , and stderr ), but there may be system-specific interfaces, for example those used by the system kernel.
Prior to the development of alphanumeric CRT system consoles, some computers such as the IBM 1620 had console typewriters and front panels while the first programmable computer, the Manchester SSEM , used a combination of electromechanical switches and a CRT to provide console functions-the CRT displaying memory contents in binary by mirroring the machine’s Williams-Kilburn tube CRT-based RAM.
On traditional minicomputers , [ dubious – discuss ] the console is a serial console , an RS-232 serial link to a terminal such as a DEC VT100 . This terminal has been kept in a secure place since it could be used for certain privileges. Large midrange systems , eg those from Sun Microsystems , Hewlett-Packard and IBM, still use serial consoles. In larger installations, the console ports are attached to multiplexers or network-connected multiport serial servers that let an operator connect a terminal to any of the attached servers. Today, serial consoles are often used for accessing headless systems , usually with a terminal emulator running on a laptop . Also, routers, enterprise network switches and other telecommunication equipment have RS-232 serial console ports.
On PCs and workstations , the computer’s attached keyboard and monitor have the equivalent function. Since it is possible to monitor the cable, it can not be extended. Often, Many facilities with servers therefore use keyboard / video multiplexers ( KVM switches ) and Possibly video amplifiers to centralize access console. In recent years, KVM / IP devices have become available as TCP / IP network and Internet access .
Some PC BIOSes , especially in servers, also support serial consoles, giving access to the BIOS through a serial port so that the simpler and cheaper serial console infrastructure can be used. Even where BIOS support is lacking, some operating systems , eg FreeBSD and Linux , can be configured for serial console operation during bootup, or after startup.
It is usually possible to log in from the console. Depending on configuration, the operating system may be used as a login session from the console as it is more trustworthy than a login session from other sources.