A floor wrench for use on a drilling rig, the floor wrench comprising: a manipulator frame configured for mounting on a drilling rig floor; a cart frame; a manipulator cart; a power tong assembly disposed on the manipulator cart, the power tong assembly configured for making and breaking joints between sections of drilling pipe; and a control system configured for controlling the movement of the cart frame within the manipulator frame, the movement of the manipulator cart within the cart frame, and the operation of the power tong assembly wherein: the manipulator frame comprises manipulator frame tracks configured for mounting onto the drilling rig floor, and wherein the manipulator frame is further configured for horizontal movement along the manipulator frame tracks; the cart frame is disposed within the manipulator frame, the cart frame configured for vertical movement within the manipulator frame; the manipulator cart is disposed within the cart frame, the manipulator cart configured for horizontal movement within the cart frame; and the power tong assembly comprises an upper tong disposed above a lower tong, the upper and lower tongs (52,54) configured for rotational movement in a substantial horizontal plane relative to each other, the upper and lower tongs (52,54) further configured for opening and enclosing a joint between the sections of drilling pipe, wherein each of the upper and lower tongs (52,54) comprises a plurality of articulated tong blocks, wherein each of the tong blocks is interlockable with another tong block and each tong block is interchangeable with any other tong block disposed in the upper or lower tongs (52, 54), wherein the tong assembly is extendable outwardly and upwardly with respect to the manipulator frame, by means of the horizontal movement of the manipulator cart extending horizontally from the cart frame, and of the vertical movement of the cart frame within the manipulator frame, respectively. a manipulator frame configured for mounting on a drilling rig floor; a cart frame; a manipulator cart; a power tong assembly disposed on the manipulator cart, the power tong assembly configured for making and breaking joints between sections of drilling pipe; and a control system configured for controlling the movement of the cart frame within the manipulator frame, the movement of the manipulator cart within the cart frame, and the operation of the power tong assembly wherein: the manipulator frame comprises manipulator frame tracks configured for mounting onto the drilling rig floor, and wherein the manipulator frame is further configured for horizontal movement along the manipulator frame tracks; the cart frame is disposed within the manipulator frame, the cart frame configured for vertical movement within the manipulator frame; the manipulator cart is disposed within the cart frame, the manipulator cart configured for horizontal movement within the cart frame; and the power tong assembly comprises an upper tong disposed above a lower tong, the upper and lower tongs (52,54) configured for rotational movement in a substantial horizontal plane relative to each other, the upper and lower tongs (52,54) further configured for opening and enclosing a joint between the sections of drilling pipe, wherein each of the upper and lower tongs (52,54) comprises a plurality of articulated tong blocks, wherein each of the tong blocks is interlockable with another tong block and each tong block is interchangeable with any other tong block disposed in the upper or lower tongs (52, 54), wherein the tong assembly is extendable outwardly and upwardly with respect to the manipulator frame, by means of the horizontal movement of the manipulator cart extending horizontally from the cart frame, and of the vertical movement of the cart frame within the manipulator frame, respectively. the manipulator frame comprises manipulator frame tracks configured for mounting onto the drilling rig floor, and wherein the manipulator frame is further configured for horizontal movement along the manipulator frame tracks; the cart frame is disposed within the manipulator frame, the cart frame configured for vertical movement within the manipulator frame; the manipulator cart is disposed within the cart frame, the manipulator cart configured for horizontal movement within the cart frame; and the power tong assembly comprises an upper tong disposed above a lower tong, the upper and lower tongs (52,54) configured for rotational movement in a substantial horizontal plane relative to each other, the upper and lower tongs (52,54) further configured for opening and enclosing a joint between the sections of drilling pipe, wherein each of the upper and lower tongs (52,54) comprises a plurality of articulated tong blocks, wherein each of the tong blocks is interlockable with another tong block and each tong block is interchangeable with any other tong block disposed in the upper or lower tongs (52, 54), wherein the tong assembly is extendable outwardly and upwardly with respect to the manipulator frame, by means of the horizontal movement of the manipulator cart extending horizontally from the cart frame, and of the vertical movement of the cart frame within the manipulator frame, respectively.