Compatibility: 3.0+
Expects: AX    1a00H
                                                                  
Returns: AL    status: 00H = is not installed
ffH = is installed
                                                                  
Info: Checks to see if the ANSI.SYS console device driver has been
installed (via CONFIG.SYS) and is resident in memory.

Use this before assuming that ANSI Console Escape Sequences will
work.

- -

INT 2fH 1a00H: Is ANSI.SYS Installed?