ANSI.SYS

ANSI.SYS is a device driver in the DOS family of operating systems that provides extra console functions through ANSI escape sequences. It is partially based upon a subset of the text terminal control standard proposed by the ANSI X3L2 Technical Committee on Codes and Character Sets (the "X3 Committee"). As it was not installed by default, and was notoriously slow, little software took advantage of it and instead resorted to directly manipulating the IBM PC hardware. A number of third-party alternatives that ran at reasonable speed were created, such as , and to attempt to change this. To use under DOS, a line is added to the (or under Windows NT based versions of Windows) file that reads: DEVICE=drive:\path\ANSI.SYS options where drive: and path are the drive letter and path to the in which the file is found, and options can be a number of optional switches to control the behaviour. may also be loaded into upper memory via /. use extended keyboard BIOS functions (INT 16h) rather than standard ones force number of lines adjust line scrolling to support screen readers or set screensize support redefinition of extended key codes independent of standard codes Once loaded, enables code sequences to apply various text formatting features. Using this driver, programs that write to the standard output can make use of the 16 text foreground colors and 8 background colors available in VGA-compatible text mode, make text blink, change the location of the cursor on the screen, and blank the screen. It also allows for the changing of the video mode from standard 80×25 text mode to a number of different graphics modes (for example, 320×200 graphics mode with text drawn as pixels, though ANSI.SYS does not provide calls to turn individual pixels on and off). The standard is relatively slow as it maps escape sequences to the equivalent BIOS calls. Several companies made third-party replacements that interface directly with the video memory, in a similar way to most DOS programs that have a full-screen user interface.