ANSI.SYS is a device driver in the DOS family of operating systems that allows a program to control the display by inserting ANSI escape sequences into its output. Without this a program could only add lines of text to the bottom of the screen, unless it directly manipulated the graphics hardware. Using ANSI.SYS would have allowed graphics device independence in IBM clones; but it was not installed by default and was notoriously slow.
Usage
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 directory 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
Features
CSI (Control Sequence Introducer) is a placeholder for the common two-byte escape lead-in sequence "" (that is, ).