00308nam a2200121Ia 4500008004100000041001200041082002100053100002500074245003900099260001700138300000800155650002300163231217s9999    xx            000 0 und d  aEnglish  a001.6404  HEL1;1  aHeld, Gilbert, David 0aIBM PC AT: User's reference manual  c1987bHayden  a453  aPersonal computers