Search

Patching service provides software firms an option to deal with the leftover bugs and is thereby helping them to keep a track of their product. More and more software firms are making use of this concept of prolonged testing. But this framework of releasing unprepared software in market involves a huge risk. The hastiness of vendors in releasing software patch at times can be dangerous as there are chances that firms release an infected patch. The infected patch (es) might lead to a hike in bug occurrence and error count and might make the software more vulnerable. The current work presents an understanding of such situation through mathematical modeling framework; wherein, the distinct behavior of testers (during in-house testing and field testing) and users is described. The proposed model has been validated on two software failure data sets of Tandem Computers and Brazilian Electronic Switching System, TROPICO R-1500.

Fully-textile systems capable of sensing multiple health parameters have the potential to enable novel wearables for a more complete picture of health status in humans. Multiple textile based sensing modalities can be incorporated in an array configuration to extract meaningful physiological information. In this paper, we present a wetness sensing technique embedded in textile fabric to detect the presence of fluids on the skin. The sensing is performed on the area between parallel stitched conductive seam-lines. Impedance measurements performed between pairs of conductive yarns in rows or columns are combined to determine wetness level of a selected fabric area. This technique enables an array-based wetness detection scheme to detect both the presence and extent of fluids within the fabric using an “outside-in” approach which also optimizes fluid detection speed. A custom-designed, modular electronic switching system provides array-based impedance analysis capability to scan multiple areas within the fabric. Overall, the techniques presented here provide a new fully-textile sensing approach to expand the sensor toolkit towards achieving multimodal and ubiquitous sensing in wearable form factors.

Fiber-optic troubleshooting usually involves checking for damaged or incorrectly installed equipment, or for components that have failed or malfunctioned in some way. Sometimes the problems are simple, but usually they require specialized test equipment to analyze and identify the problem. This chapter opens by summarizing common problems likely to be encountered in fiber-optic systems. Then it describes important test equipment and its operation, drawing on measurement concepts you learned in Chapter 17. Finally it reviews some simple procedures to track down problems. The techniques covered are specific to fiber optics, not general to communications. That means you will learn ways to spot a broken cable, but not how to diagnose the hardware or software in an electronic switching system. This chapter is an introduction to basic concepts and the most important equipment, not a step-by-step description of everything you will need to know on the job. That’s a book or a course in itself. Think of it as a quick introduction to fiber-optic first aid. It won’t teach you how to perform delicate surgery on the network, but it will help you respond intelligently if the system goes down.

The idea of time slot interchange (TSI), the fundamental concept of implementing time switches in digital switching systems, was first conceived by Dr. Hiroshi Inose, then at the University of Tokyo, Japan, in 1957 while he was a visiting consultant at Bell Telephone Laboratories. The TSI collects each subscriber's pulse code modulation (PCM)-coded voice information to be stored into a small time interval (time slot), and then aligns multiple time slots on a common transmission bus to constitute a repetitive frame. The TSI enables any time slot to be interchanged with another time slot within a frame once the time slots in the frame are buffered in memories. Thus, TSI gives the time switch functionality equivalent to N-input by N-output space switch functionality. He built a prototype digital time-division multiplexing (TDM) electronic switching system called CAMPUS, which is based on the TSI principle, using a magnetostrictive delay line as a memory device. TSI received little attention until the end of the 1960s because memory devices were very costly. However, with the rapid advancement of semiconductor technologies in the 1970s, the TSI scheme became more widespread. TSI was first commercially deployed in 1976 as the time switch of ATT he was also actively involved in a number of Japanese governmental and international activities in the area of communications and information processing technologies. His final work was the establishment of the National Institute of Informatics (NII) in 2000, Japan's sole comprehensive academic institute in the field of informatics that seeks to advance integrated research and development activities in information-related fields.

The first events in the history of exploiting security date back to the days of telephony. Telephone signals were sent via copper cables. Telephone lines could be tapped and conversations could be heard. In the early days of telephone systems, telephone operators intentionally misdirected calls and eavesdropped on conversations. In the 1970s, a set of people known as phreakers exploited the weakness of digital switching telephone systems for fun. Phreakers discovered the signal frequency at which the numbers are dialed and tried to match the frequency by blowing a whistle and fooling the electronic switching system to make calls for free. Among these phreakers, John Draper found that he could make long-distance calls for free by building an electronic box that could whistle different frequencies

Burn-in is an effective means for screening out defects that contribute to infant mortality failures. Various studies have been conducted for determining the optimum burn-in time for a device. However, most of them assume cost models, which are difficult to quantify. In this article, we take a more realistic approach for determining the effective burn-in time for a PBA(Printed Board Assembly) to satisfy the customer requirement that the failure rate after burr-in be less than a specified value. The proposed method is applied to two types of PBAs used in a certain electronic switching system.

Previously, a substance identified as ammonium sulfate was found on the speech path contacts of XS-type crossbar switches in the electronic switching system of NTT. On the basis of this finding, the contacts of 99% Au/1 % Ni alloy in contact with Pd were developed by the author's group more than ten years ago for the pushbutton dial contacts of telephone sets. These contacts showed excellent performance and are still in use at the present. This development depends on the hypothesis that some metal oxides have the effect of preserving contact performance against the influence of air pollution. In this paper, the hypothesis, experimental results in the investigation of the properties of the Au-Ni alloy surface, and applications of this alloy for electrical contacts are described. The experimental results are as follows: (1) by heating the Au-Ni (Ni 1%) alloy, it was confirmed that nickel oxide was accumulated on the alloy surface; (2) by measuring the contact angle of a water droplet on the Au-Ni alloy, the relationship between the angle and accumulation of nickel oxide was obtained; and (3) by operating the contacts combined with Au−1 % Ni and Pd which are similar to the actual use of contacts, the characteristics and the size of the formed powder were evaluated.

Single Phase Induction Motors are not self-starting unless they are started as quasi-two phase motors. This necessitates a starting winding, with or with out starting capacitors, which is switched out once motor is accelerated. A centrifugal gear having flying weights and a mechanical contact type switch is most commonly used to do this function. This paper describes a non-contact type; non - mechanical type, electronic switch that eliminates contact sparking and mechanical assembly criticality, thereby improving the reliability, motor life and servicing cost. The various types of electronic starters available in market operate on different principles like time delay or capacitor voltage or winding turns ratio or phase difference between start and run windings. The operation of the electronic starter, described in this paper, is based on actual shaft speed, similar to mechanical switch, but switching the capacitor / winding electronically. The starting capacitor and/or the winding is switched out based on the simple speed feed back data obtained. The switching instant is decided by a micro-processor based logic circuit using speed feedback and the switching is done using single/multiple semi-conductor switches. Electronic starter reduces the inventory cost due to its flexibility.

In order to establish rapid diagnosis in a signaling service, this study has developed a system which can analyze the status of the signal sent from/received by signaling equipment, providing for a fully electronic switching system such as TDX. The system has a function of acquiring the PCM signal of the preferred channel from the subhighway (SHW), and then it classifies the type of signal such as R2MFC/DTMF/CCT/VOICE, and finally discriminates the digit.

The interwork, hardware configuration, and design specification of a recorded announcement system are presented. The system, which is called the ready-made message announcement system (RMAS), has been developed for the TDX-10 electronic switching system. The main function of the system is to give the calling party an announcement message of why a call was not completed and what further action should be taken or to announce a message as a special service when a call was processed normally. RMAS consists of a software unit, an announcement primary-function software unit (APSU), and a hardware unit, called the announcement primary-function hardware unit (APHU), which is described. >

Describes the EWSD basic architecture and then elaborates on its evolution starting from its first field introduction through to the early 1990s. The implementation of some major features like Signaling System 7, ISDN and Centrex is first explained. The system evolution is then presented, focusing on subscriber line cards, peripheral redundancy and remote units, and the coordination processor. The introduction of new product lines based on EWSD technology, such as digital mobile systems and intelligent network products is discussed. >

Historically, electronic switching systems power supplies in the USA have been grounded using the "isolated ground" philosophy. In Europe, the "mesh earthing system" is most prevalent. This paper discusses and compares the isolated ground and mesh earthing system methods as used in the Lucent Technologies 5ESS(R) electronic switching system.

A new approach to customer-oriented end-to-end testing is proposed as an integral part of the architecture for enhancing the reliability of AT&T Bell Labs' products and the quality of their ISDN services. The basic idea is to create virtual customers who are constantly using the system as real customers, thereby continually exercising and monitoring the system's operations in a real working environment. Any potential system problem will thus be detected first by the virtual customers. Therefore, problems are expected to be corrected before any reaction from the paying customers. Such a proposal appears to be relatively simple. The important question concerns whether one can emulate the customers who can effectively set up end-to-end dialogs as done by real customers. The objective of this experiment on the 5ESS (electronic switching system) is to apply this technique to implement virtual customers as a means of on-line, real-time testing of the system's capability in providing high quality customers services. Although a very limited data collection has been taken, the on-line customer-service-oriented testing approach has been demonstrated to be an effective means of uncovering difficult problems in a real system environment. >

This paper describes a process to automatically restore DC power to transport and electronic switching system (ESS) equipment without manual intervention, after an extended battery discharge below the minimum operating voltage of the equipment. Manual intervention, in terms of this process, includes initialization of software and recharging of system capacitance. High level design criteria for restoration of the telecom system to the call processing or fully operational state are discussed.

The telephone message delivery system (TMDS), an effective voice messaging system based on the signal computing system architecture (SCSA), is proposed to increase the call completion rate of the PSTN. The TMDS is composed of two mutually interactive functions. One is a conditional re-routing function in the central office (CO) electronic switching system (ESS). The other is a supplementary computer control system which handles incoming or outgoing calls, and provides subscribers with various message management functions. The SCSA is adopted to maximize the system performance. The implemented system has been tested in three fields for three months. This paper also evaluates the field trial results.

A modern electronic device is a complex 3-dimensional structure that consists of millions of components for each single IC chip. This complex and delicate device requires effective encapsulation and packaging to ensure its long-term reliability. The device encapsulant requires not only excellent electrical, physical properties, but also suitable mechanical properties for the hostile and extreme temperature cycling requirements. Hence, the mechanical behavior of the encapsulant plays a critical role in the device reliability.Low stress encapsulants are the preferred choice for microelectronic packaging. Silicone-base materials, with their low modulus and excellent electrical properties, are one of the best encapsulants. However, the intrinsic elastic (to soft gel-like) silicone properties provide weak mechanic protection of the IC device. We have, however, modified the silicone material with a high loading of silica to improve its mechanical and physical properties. This high silica filler loading material improves its mechanical property, but it also increases its modulus. This modified high modulus silicone material tends to have microcracks during the high temperature cycling testing. In this paper, I will describe a modified version of the enhanced mechanical property silicone-base encapsulant, the materials formulation, the curing and the thermal mechanical protecting mechanism and its application to AT&T's No. 5 Electronic Switching System (ESS) Gated Diode Crosspoint (GDX) hybrid IC supplemental insulating layer (SIL) materials.

This paper proposes an extensible distributed architecture that is applied to an experimental switching system called expect for Extensible Packaged Electronic Switching System. It consists of microprocessor units and a common bus with two different kinds of optical arbiters. With its architecture, new functions can easily be added with new processing software-hardware packages where no modification is necessary to the existing system.

In May of 1976, a new Common Channel Interoffice Singnaling (CCIS) system linked together the last new No. 4A toll crossbar office in Madision Wisconsin and the first No. 4 ESS toll office in Chicago, Illinois. This was a major milestone in a long-range program to achieve a nationwide Stored-Program Controlled (SPC) network of stored-program controlled switching offices interconnected by a new high-speed, high-capacity interoffice signaling system, CCIS. The SPC network will provide faster, more reliable communication services. An evolutionary transition to the SPC network is in progress. CCIS is now being implemented in the toll or long-distance network. It will subsequently be extended to Traffic Service Position System (TSPS) units and to Electronic Switching System (ESS) local switching offices to provide customer-to-customer CCIS service.

Interprocessor communications as well as interconnection among processors is an important design factor in an electronic switching system with distributed control. This paper proposes a new scheme for a message transfer algorithm in interprocessor communications, called a gating scheme. A major difference from the usual clocked scheme is that a processor never requests message transfer to another processor until it has finished processing all tasks in that processor; in the clocked scheme a processor periodically sends requests to another processor. A queueing model is presented for the performance evaluation of the gating scheme. Various performance measures are derived using the theory of piecewise Markov process. The gating and clocked schemes are compared numerically.

Specific attempts have been made at Bell Laboratories to shorten development intervals, to improve the quality of system design, and to improve unit, manufacturing, and system testing by widespread application of the LAMP system during development of the 1A Processor and No. 4 Electronic Switching System. LAMP has played a major role in two areas of the design process — design verification and fault simulation. Although ten major digital subsystems of No. 4 ESS and the 1A Processor are now being simulated on the LAMP system, this paper describes the experience gained during development of two of the 1A Processor subsystems, central control and program/call store.

The processor in an electronic telephone switching system must be designed to efficiently and reliably process telephone calls. Because of the extended life span of a telephone switching system and the nature of the function it provides, it is advantageous to build a great deal of flexibility into the processor design. This paper provides details of a microprogram control design philosophy for the development of a medium-size processor∗ that provides the required flexibility. The aspects of the microprogram control that make it very suitable for the design of a processor in a fault-tolerant system are also described.

This paper describes a process to achieve modular software for switching systems in a way similar to hardware design manufacturing the components first, then constructing a system using the components needed. To reduce the software maintenance cost in the case of changing switching functions, the following factors were studied: 1) modularity corresponding to divided switching functions; 2) interface standardization among the modules; 3) software structure applicable to different systems. In the trial manufacture for the data switching system, the authors were able to reduce manpower required for designing and debugging, and were able to obtain a structural simplicity and modular portability to other switching systems.

This paper provides a general description of the circuits and units that make up the No. 10A Remote Switching System. The components of the system were designed to provide the operating and maintenance features of an electronic switching system, while keeping size, cost, and external equipment to a minimum. Fundamental new design approaches are described.

Reliable Multiwire circuits have been developed. The objective of this development was to reduce design and assembly cost of backwiring boards in an electronic switching system. To realize high holeto-wire connection reliability, various factors were investigated and the following results have been obtained. 1) The use of Pyre-ML as a wire insulating material is the most effective for obtaining high connection reliability because of its solubility in alkaline type plating solution. 2) In manufacturing processes, cleaning of resin smear is the most important process. 3) Pads around plated through-holes are effective for reduction in thermal expansion around plated through-holes and failure rate is reduced to 2 percent with pads. By using these technologies, Multiwire circuits with a wire thicker than 0.09 mm have obtained equal or higher connection reliability, compared with multilayer printed circuits.

When a relief toll switching system is used to alleviate the exhaust problem of an existing toll switching system of the same generic, type, a rehoming program (specifying amounts and timings of trunk rearrangements) is dictated primarily by the ratio of the monetary discount rate to the traffic growth rate. If this ratio is greater than unity, the rehoming strategy calls for a conservative program of restraint whereas if this ratio is smaller than unity, the rehoming strategy adopts an aggressive program of activity. When the relief and the existing switching systems are not of the same type, the lower trunk maintenance expenses on the relief switching system provide an impetus to rehome more existing trunks onto the relief switching system. It is found that this stimulation of early deloading affects the rehoming strategies significantly. Depending on the amount of stimulation involved, a conservative rehoming program could be changed to a moderate and even an aggressive one.

The loop range extension (LRE) feature refers to electronic switching system (ESS) modifications required to implement concentrated range extension with gain, which involves the integration of switching and transmission technologies in the Central Office. This paper describes the interfaces between the LRE feature and Nos. 1/1A and 2/2B ESS's; it provides a brief description of the ESS networks and details the hardware connections and software processes required for LRE functions. Also provided are network administration considerations required in support of the feature.

High density Multiwire circuit technology which can lay two insulated wires between throughholes on 2.5 mm centers has been developed. To reduce crosstalk smaller diameter wires were adopted instead of conventional 0.16 mm diameter wires. Wire breakage and wiring mistakes, which occur in high density wiring, can result from improper wire tacking. A newly developed tackless wiring technique can reduce these problems. The new technology has been applied to backplane wiring boards in an electronic switching system.

The No. 4 Electronic Switching System has been planned to provide operational ease in the efficient management of traffic-sensitive equipment for the purpose of maintaining a high quality of service. The network management function has the goal of optimizing the completion of calls during periods of traffic stress. In No. 4 ess, innovative real-time control and surveillance features are provided to meet this goal. Traffic administration involves the activities of personnel in managing the traffic-sensitive equipment in an efficient, timely, and economical fashion. These activities depend upon the collection of data which reflects the operating characteristics of the No. 4 ess, and the reporting of information in a form tailored to the user functions.

With the introduction of the 2B Extended Feature Generic #3 (2BE3), No. 2B Electronic Switching System has modernized its arrangements for billing and traffic measurements. High-speed, synchronous data links are used to teleprocess billing information to the No. 1A Automatic Message Accounting Recording Center and to forward traffic data to the No. 1A Engineering and Administrative Data Acquisition System Center. This article describes the implementation of these features in the 2BE3 generic and how these new interfaces have resulted in more precise and more reliable data.

This article is an introduction to a series of articles that describe the No. 4 Electronic Switching System. Objectives and the organization of the system are given and the overall operation is explained.

This paper presents a review of the main telecommunications systems now under development in France. First, it gives the general objectives, the basic options, and the general design of the new electronic switching system E. 1 defined by CNET, with the principal characteristics of the E.10 and E.12 variants, and general planning of studies and development in process in this field. Then a summary of the new transmission systems under development such as digital systems on cables, radio relays, or circular waveguide, as well as analog systems, including submarine and space systems is given. Finally, some considerations are given to the increasing use of information processing for the telecommunication network, and to the development of specialized networks for new kinds of information.

The use of a Stored Program Electronic Switching System (SPESS) in a university program of instruction and research is described. University involvement with telephony in general and telecommunications switching in particular is discussed, the SPESS facility is described, and Rensselaer's program of instruction and research is outlined.

Common channel interoffice signaling (CCIS) is provided as an integral part of No. 4 ESS. The unique hardware required for CCIS consists of a common systems CCIS terminal and associated access circuit, continuity check transceivers, and unitized terminal equipment for CCIS trunks. The control of the CCIS hardware and the logic required for CCIS administrative functions is provided by programs resident in the 1A Processor. This paper discusses the system design requirements, the signaling hardware, and the software design for CCIS in the No. 4 Electronic Switching System.

The No. 1/1A Electronic Switching System (ESS) will play an important role in the evolving Stored Program Controlled (SPC) Network because, as a major electronic switching system for local and combined local/toll service, it provides direct interfaces to many of the Bell System's customers. It provides important capabilities required for System 800 Service and for a variety of other new SPC network services. This paper describes several of the basic SPC network capabilities provided by the No. 1/1A ESS. It also describes the architecture and implementation of its common-channel interoffice signaling (CCIS) subsystem, CCIS call-processing software, and System 800 software.

This paper proposes a new sharing of call processing functions between a terminal and a switching system, taking recent technology advances into consideration. Information and its processing in an electronic switching system are defined and their calculation method is shown to discuss the function share. Numerical examples of information and its processing amount are obtained using NTT's commercial system, D-10, for an example. Possibility of function distribution to a subscriber terminal is discussed, based on information and its processing amount obtained by the analysis. The amounts of information and its processing in an existing switching system are estimated to both be reduced to about 35 percent by distributing to a terminal function, such as subscriber's action detection, audible signal generation, dialed number storage and display and so on. On the other hand, the information and its processing amount shared by the functional terminal are estimated to amount equivalently only to 5 and 10 percent respectively of those of an existing switching system, because introduction of functional terminals eliminates conventionally required time urgent information processing. Therefore, the total information and its processing amount in the telephone system incorporating functional terminals are estimated to be about 40 and 45 percent of those solely shared by an existing switching system, respectively. It is also mentioned that the functional terminal guarantees the variety of services which enables economical use of the telecommunication network.

An experimental 2 Mbit bubble memory unit containing thirty-two 64 kbit chips has been built and tested for the file memory in electronic switching systems. The memory unit has 5 ms average access time and 1.6 Mbit/sec data rate. The memory unit has been subjected to extensive functional and environmental tests for about 1 year to insure a practical file memory. Overall 8 Oe bias field margin ever the -10°C to 50°C temperature range is obtained. No resonance and no bias field margin drift were encountered under 5 to 55 cps and 5 G of vibration (G=980 cm/ sec2). Non-volatile storage at -40°C and 70°C were demonstrated. A read error rate of less than 9×10-12/read was achieved. These results insure a practical use electronic switching system file memory.

This paper highlights the systematic evolution of the No. 2/2B Electronic Switching System (ESS), describing both hardware and software changes. It also introduces the subsequent articles that describe the modern interfaces and modern development environment enjoyed by the system. The No. 2 ESS was the first electronic switching system specifically designed for the suburban community. Subsequent incorporation of a more flexible and powerful processor provided a basis for a large increase in processing capacity and a continuing modernization of system structure. The evolved system, the No. 2B ESS, is now rich in features and offers modern administrative and maintenance capabilities.

The No. 4 Electronic Switching System, a high capacity, toll and tandem system based on digital time division switching was first placed in service in Chicago on January 17, 1976. It has provided improved system operation and new service features at reduced cost in comparison to the existing electromechanical systems. The flexibility of system architecture has permitted the evolution of the No. 4 Electronic Switching System. Since cutover of the first system, the introduction of improved hardware and software has made possible additional savings in equipment as well as reducing power and space requirements by approximately 60 percent. The introduction of the 700 ns stores has increased the computing power of the processor by 30 percent, Which has made possible the addition of new revenue producing features without reducing switching capacity. With the new features, No. 4 ESS is now being used in the North American domestic toll and tandem as well as international switching networks. In addition, the move toward centralization of maintenance and administration of the system will further reduce maintenance costs. The overall performance of the 21 in-service systems has been excellent.

As a major modernizing improvement data links for three important functions have been added to the 2B Electronic Switching System (ESS). The data-link system was designed with a layered architecture using an enhanced subset of the X.25 protocol. Levels 1 and 2 of the protocol are implemented in the hardware and software of a new device, the Serial Peripheral Unit Controller/Data Link (SPUC/DL). Within the SPUC/DL itself, check circuitry and software are used for error detection. A second SPUC/DL for each critical application provides redundancy on either a dedicated or dial-up basis. An elaborate diagnostic program within the 2B ESS can be invoked automatically or manually. This paper discusses some of the issues in retrofitting the BX.25 protocol to pre-X.25-speaking machines.

This paper focuses on the design of recovery strategies that have been developed to give the No. 4 Electronic Switching System (ESS) the necessary high level of fault tolerance. Reliability and availability are the key watchwords to operational integrity in the No. 4 ESS. It is the world's largest toll and tandem switching system, capable of handling 616,000 call attempts per hour, and serving up to 100,000 active terminations. With a downtime objective of less than two hours in 40 years, the No. 4 ESS must be designed to be very fault tolerant viewed from the caller's perspective.

Since the cutover of the first No. 4 Electronic Switching System (ESS) office in January 1976, a program of system evolution has been carried out. As a result significant cost reduction was achieved, major new features have been added to the No. 4 ESS, and the system's performance has been enhanced. This paper gives an overview of the continuing development of the No. 4 ESS carried out during the period 1976 to 1980 as a prologue to a series of papers in this volume which describe some of the specifics of this activity.

This paper describes the system organization and objectives of the No. 2 Electronic Switching System. The place of No. 2 ESS in the Bell System and the design approach used are outlined and traffic capacity estimates are discussed. This paper also serves as an introduction to the detailed set of papers which follow.

The flying spot store is a semipermanent information storage system developed for use in an electronic switching system which utilizes cathode ray tube access to information stored on photographic emulsion. Parallel optical channels are used to provide high capacity and parallel readout. A feedback system provides rapid and precise beam positioning for writing and readout. This paper describes the fundamental design considerations for memory systems of this type, stressing physical realizability, speed, capacity and other system features. The characteristics of a laboratory model are presented.

RESEARCH IN JAPAN on electronic telephone switching techniques has made remarkable progress since the close of World War II. Among numerous trial models built are the ?-type electronic switching system developed at Electrical Communication Laboratories of Nippon Telegraph and Telephone Public Corporation, announced in December 1955,1?3 and the parametron-type semielectronic switching system, publicized in December 1956 by two of the authors of this paper. Developmental research has continued on the latter system as well as on electronic devices to be used in this field.

Translations are the means of storing and retrieving office and customer information in a No. 1 electronic switching system installation. The translation scheme must be sufficiently general to handle special telephone services in addition to the items stored as cross connections in present telephone systems. The categories of translation information, the techniques of storage, the means for specifying translation data, and means for making changes therein, are described in this article.

A combination of space division and time division networks makes possible an 800 to 4000 line switch unit private branch exchange for the No. 101 electronic switching system.

This article describes the system organization and objectives of the No. 1 Electronic Switching System Arranged with Data Features. The new hardware and software designs required to adapt a No. 1 ESS to a store and forward system are outlined with emphasis on the techniques used to get large system capacity, continuous reliable operation, and flexible service features. System operation, traffic capacity, and use of the new system are also discussed in this introduction to seven detailed articles.

This local exchange system features new customer services, remotely controlled concentrators, and automatic maintenance and operation facilities. It comprises central control with a memory bank and a speech path network with bistable ordinate switches.