Mark sense

Abstract: A mark sense card reader employs dual-threshold circuitry to indicate the presence, absence or inability to determine the presence or absence of marks such as pencil marks on a card. The circuitry includes a light-sensing transducer coupled to first and second differential amplifiers. The first such amplifier produces an indication only when a mark is definitely present. The second such amplifier produces an indication both when a mark is present and when the light level is such that no decision can be made as to whether or not a mark is present. The presence of this last indication concurrently with the absence of the other such indication means that no decision can be reached as to whether or not a mark is present. This situation may occur in cases of a poor erasure, or very light marks and in such cases the circuitry of the present disclosure causes the card to be rejected.

Abstract: An optical mark sense tab card reader which utilizes an improved fiber optical sensing head having a plurality of elongated sensing areas, the major axis of each of which is aligned at an acute angle to the direction of travel of the tabulation card being read. This allows the card reader to efficiently and reliably read information off of tab cards where the information is presented in either slanted or the standard to vertical mark areas.

Abstract: Publisher Summary This chapter presents the details of the history of computer development at IBM. IBM entered the computer field with the installation of a 701 in the IBM Technical Computing Bureau in New York City in December 1952, and the shipment of the first customer machine to the Los Alamos Scientific Laboratory early in 1953. It also describes certain characteristics and features of the 701 hardware and software, and the technology from which the 701 was developed. The 701 was of the von Neumann type, a binary, 36-bit word machine with parallel arithmetic, three arithmetic registers, and 32 single-address instructions. SHARE was a model for user groups both with respect to other products in IBM and in regard to many other manufacturers of computers. It has been a teaching device and a reaction device of great help to IBM in its product development. The increasing acceptance of the 701 in late 1952 led inexorably to the need for a medium-size and medium-price computer that, among other things, would succeed the card-programmed electronic calculator (CPC).