X0201 4 2003-09-10 1 0000704914 DATAKEY INC dkey 0001044321 MARXE AUSTIN W & GREENHOUSE DAVID M 153 E 53RD ST 55TH FL NEW YORK NY 10022 0 0 1 0 Common Stock 2003-09-10 4 S 0 14000 0.6248 D 1081141 I By Limited Partnerships Common Stock 2003-09-11 4 S 0 12700 0.6483 D 1068441 I By Limited Partnerships This is a joint filing by Austin W. Marxe (Marxe) & David M. Greenhouse (Greenhouse). Marxe & Greenhouse share voting and investment control over all securities owned by Special Situations Cayman Fund, L.P. (Cayman), Special Situations Private Equity Fund, L.P. (PE), Special Situations Technology Fund, L.P. (Tech) & Special Situations Technology Fund II, L.P. (Tech2), respectively. 159,166 shares of Common Stock and 166,666 Warrants held by Cayman, 171,100 share of Common Stock and 300,000 Warrants held by PE, 6,675 shares of Common Stock and 35,458 Warrants held by Tech and 47,667 share of Common Stock and 181,209 Warrants held by Tech2. The interest of each of Marxe and Greenhouse in the Common Stock owned by Cayman, PE, Tech and Tech II is limited to the extent of his pecuniary interest, if any, in Cayman, PE, Tech and Tech II, respectively. Austin W. Marxe 2003-09-12 David M. Greenhouse 2003-09-12