Recently there has been increasing attention to character recognition/graphical user interfaces under the name of “gesture input”. This technique actually has a long history: “sketch recognition” interfaces of 15 or more years ago were highly praised [Applicon 73], and user interfaces using handwriting input before the wide use of text keyboards were one of the first research goals in computer science [Bledsoe 59]. The underlying character and symbol recognition technologies have been a major research area in their own right since the early 1950s [Suen 80].

A performance analysis of an automatic signature-verification system based upon the use of a three-axis force-sensitive pen to transduce the dynamics of the handwritten signature into electrical signals suitable for real-time computer processing is presented. False-rejection and imposter-acceptance (i.e. type I/type II error) curves are presented for a variety of operating conditions. For typical `real world' conditions, the equal-error rate (where type I error rate equals type II error rate) is about one percent. The performance analysis was based upon a data base of 5220 true signatures obtained from 58 subjects over a four- month period, and 648 attempted forgeries obtained from 12 forgers. The forgers were given copies of the true signers' signatures, told how the verification system operates and what it measures, allowed to watch video tapes with close-up views of the signatures to be forged as they were being written, and allowed to practice for a three-week period. Particular advantages of the signature-verification system reported here are high performance, low storage requirements (typically 200 to 300 bits per user), and low-cost implementation in a stand-alone microprocessor unit.

An all-magnetic logic scheme is one with which a workable digital system could be constructed involving only magnetic elements, current-carrying conductors, and sources of clock pulses. Historical developments of both resistance schemes (dependent upon coupling-loop resistance) and nonresistance schemes (possessing at least first-order independence of coupling-loop resistance) are described, with reference to all relevant published work known to the authors. Included are: 1) schemes using electric-circuit transfer linkage with simple cores, multipath cores, and thin-film elements, and 2) schemes using continuous magnetic structures where transfer linkage is purely magnetic.

A logical design technique is developed for use with the particular module developed for this system. The detailed properties of this module, as well as the philosophy that led to its particular form, were covered in Part I of the paper. Briefly, the module forms the (inclusive) OR function of two input variables. This function can subsequently be transmitted to three receivers, each transfer being independently logically positive or negative. The read-outs are nondestructive and the transmitter module must be explicitly cleared before read-in is again possible. In view of the relatively small fan-in and fan-out for this module, and since only the OR function can be directly formed during any single transfer, complex logic functions must be formed slowly, a step at a time. This step-by-step generation of functions results in the need for more modules than might otherwise be required, but aside from that, the synthesis techniques are not particularly different from those of customary logical design. In particular, the design of an arithmetic unit designed for decimal addition, subtraction and multiplication is outlined. Some comparisons are noted between this particular all-magnetic logic scheme and conventional core-diode schemes. Comparisons are also made between magnetic logic schemes in general and some other realization schemes, such as ac-operated parametrons and conventional transistor systems.

This paper describes the circuits used in a decimal arithmetic unit which utilizes ferrite magnetic elements and copper conductors only. The arithmetic operations of addition, subtraction, and multiplication are performed with a product and sum capacity of three decimal digits. The sole logical building block of this system is a two-input inclusive-OR module with a fan-out capability of three with any desired logical positive and negative combination. The system involves the use of some 325 modules, each of which contains two magnetic multiaperture devices (MAD's). This paper gives a complete description of the circuit and physical arrangement of the machine. The system is controlled from a manual keyboard, and readout from the machine is via incandescent lamps controlled directly from the MAD elements, no intermediate elements being required. The "worst case" drive-pulse amplitude range for the completed machine, varying all clock pulses simultaneously, is ± 10 per cent.

A technique is described for detecting specific sequences of pulses occurring on a net of input lines. This technique lends itself to realization in all-magnetic networks by the use of multi-aperture magnetic devices (MAD's). The resulting circuits are remarkably simple and reliable. Processing rates in excess of 100,000 characters per second may be achieved. Examples are given of systems using arrays of such detectors. One example involves a system for detecting handwritten characters which makes use of a special pen having the property of generating specific sequences of pulses as symbols are written. The second example relates to the problem of monitoring text for the detection of specific words (letter sequences) and phrases (series of sequences).

Magnetic switches are described in which the current from an energizing source is guided or steered through one out of many possible parallel branches, the conducting branch being selected by the presetting of appropriate magnetic elements. Only a few tubes are required for energization, and the outputs, obtained with reasonable efficiency, are substantially independent of exact circuit parameters. Current steering is achieved either by core-diode combinations or by transfluxors. Decoding switches, of both types, for the selection of one out-of-many outputs according to an input code are described in detail. A current of precise amplitude of the order of amperes is switched to a selected path in microseconds. Steered decoders are ideal for addressing core memories. A commutator switch for delivering sequentially a given current to a number of loads is described. Current steering makes possible simple magnetic counters and universal code converters. Experimental results of laboratory models of decoders and commutators are given. The principle of current steering broadens greatly the usefulness of magnetic switches by providing economy of associated electronic drivers and accuracy of switched currents.