Thankyou all for the flurry of responses. What an excellent forum. Absolutely right, on closer inspection it turned out not be an executable of any description whatsoever. I was sold an expensive dummy there.

Hi, I need to run a DOS executable of size 1040Kb. When I execute this in a Windows XP DOS box I get, of course, the message 'program too big to fit in memory'. Does DOSBox allow me to optimise RAM for DOS executables like we did in the old days before Windows?