Provides character-based terminal support for the local graphics display and keyboard.
The lft file is the application interface to the "Low Function Terminal (LFT) Subsystem". It provides support for a VT100-like terminal which is associated with the local graphics display and keyboard. It provides only character operations and is designed to be used during system installation, startup, shutdown, and stand-alone diagnostics.
The terminal supports a single logical screen size of 80 characters and 25 lines and a single color. Dynamic reconfiguration is not supported, configuration changes take effect at the next system startup. In the cases when multiple fonts may be used to achieve the 80x25 screen size, the user may set which font is used with the next system restart. See "LFT User Commands" for details of the available commands.
When multiple displays are available, the LFT Subsystem initially uses the default display. The user may change to another display and set the default display. See "LFT User Commands" for details of the available commands.
The LFT device driver supports the lft special file. The device driver is a streams based driver. It handles only the system attached keyboard and graphics displays.
Certain LFT ioctl commands allow graphics subsystems, such as AIXwindows, to obtain exclusive use of the displays, a right initially held by the LFT. However, this is done by the Rendering Context Manager (RCM) on behalf of the graphics subsystem. See "Rendering Context Manager" for details of the procedure for becoming a graphics process.
The lft special file supports the open, close, read, write, and ioctl subroutines.
The functions performed by the ioctl commands fall into three categories:
| LFT_QUERY_LFT | Query common LFT information. |
| LFT_QUERY_DISP | Query display information. |
The lft special file is part of Base Operating System (BOS) Runtime.
Low Function Terminal (LFT) Subsystem Overview in AIX Version 4.3 Kernel Extensions and Device Support Programming Concepts.