Int 2F Fn 4800  - Dos 5+ Doskey - Installation Check                       [K]

   AX = 4800h

Return: AL = nonzero if installed
       (DOS 5.0 and 6.0 return AX=AA02h, Novell DOS 7 returns AX=EDFFh)
       ES = segment of DOSKEY resident portion
       DX = ??? (Novell DOS only; 02E6h for shipped v0.01)

Notes: DOSKEY chains if AL is not 00h or 10h on entry
   this function is supported by Novell DOS 7 DOSKEY

See Also: AX=4800h"PCED",AX=4810h