mov ax, 4800h ;Get DOSKEY.COM Installed State
int 2Fh ;Multiplex Interrupt
cmp al, 00h ;00h means not installed
Get DOSKEY.COM Installed State (Interrupt 2Fh Function 4800h) determines whether the resident portion of the Doskey program has been loaded.
This function has no parameters.
The AL register contains a nonzero value if the Doskey program has been loaded or 00h if it has not.
Interrupt 2Fh Function 4810h Read Command Line