Time-sharing System Research Articles

Fernando Corbató: Time-Sharing Pioneer, Part 1

Fernando Corbato is best known his work developing time-sharing operating systems. Early in his career, Corbato had a key role in the development of both the Compatible Time-Sharing System (CTSS) and Multics at the Massachusetts Institute of Technology in the 1960s. In 1990, Corbato received the Turing Award for his pioneering work in organizing the concepts and leading the development of the general-purpose, large-scale, time-sharing and resource-sharing computer systems, and he was made a fellow of the Computer History Museum (CHM) in 2012. This interview is the first in a two-part Annals series based on an oral history conducted by Steven Webber the CHM in February 2006.

Programming Primes (1968–1976): A Paradigmatic Program and Its Incarnations in the Age of Structured Programming

In response to the so-called ‘software crisis’ of the late 1960s, many approaches were proposed to turn (parts of) software engineering and programming into more systematic disciplines, to turn an art into a science. This paper studies one popular example often used in these proposals, the computation of a list of primes, to discuss some salient features of the proposed programming paradigms. It also looks at the actual implementation in the early 1970s of the prime program on a time-sharing system (MULTICS) and on a complex scientific computer (ILLIAC IV). Confronting theory with practice uncovers what the programming paradigms fail to grasp: the interaction with the user and the interaction with the machine.

From the Mainframes to the Masses: A Participatory Computing Movement in Minnesota Education

Abstract Historians have demonstrated how systems like Usenet and Minitel fostered the social practices that we now associate with the TCP/IP Internet, but no one has considered networked computing in education. From 1965 to 1975, Minnesota implemented interactive computing at its public schools and universities with time-sharing systems—networks of teletypewriter terminals connected to computers via telephone lines. These educational networks, created with different priorities from military-sponsored networks, were user oriented from the start and encouraged software sharing and collaboration. Focusing on the educational setting gives us a history of the Internet firmly grounded in the social and political movements of the long 1960s.

Computer capacity utilisation – a multilevel perspective on decades of decline

This article uses a multilevel perspective to explain why there has been a dramatic decline in the utilisation of computer-processing power during the last two to three decades. It identifies that computers have been used in two different ways – either as single-user systems where each users received his or her own computer or as time-sharing systems where each computer was shared by several users. It finds that the time-sharing systems made considerably better use of the computers' resources than the single-user systems and that the utilisation of computer-processing power began to decline as single-user microcomputers began to replace time-shared minicomputers and mainframes. The article argues that this development contradicts much of the recent research on capacity utilisation, but argues that this contradiction can be explained by analysing this development as a transition process with multiple levels of interaction.

Stability Analysis of <inline-formula> <tex-math notation="TeX">$p$</tex-math></inline-formula>-Persistent Slotted CSMA Systems With Finite Population

When multiple users are communicating with an access point based on a random access, the stability region is known as all possible combinations of the mean packet arrival rates to keep their queue lengths bounded. This paper investigates the stability region of $p$ -persistent carrier sense multiple access (CSMA) systems, where two users have different mean packet arrival rates and (re)transmission probabilities. We then extend our results to $p$ -persistent CSMA systems with $N$ users and discuss applicability of our results to IEEE 802.11 systems with the basic and request-to-send/clear-to-send access mechanisms. In numerical studies, we show the stability region by varying system parameters such as packet arrival rates, (re)transmission probabilities, and radio channel errors, and how the stability region of $p$ -persistent CSMA systems gets close to that of a time-sharing system.

My Corner of the Time-Sharing Innovation World

The author reflects on his career in the computing world, specifically his work in early time-sharing system development, and the almost accidental steps that put him in touch with some of the technical giants of the industry in Berkeley and then led to his years at Norsk Data in Norway. He explains how his contribution to ND with regard to operating system technology contributed significantly to the company's astonishing growth.

Messaging in the Early SDC Time-Sharing System

In the early 1960s, the time-sharing computer at the System Development Corporation had several messaging commands through which remotely logged in users communicated with one another and with the system operator. These commands were used for system operation and for sending information to remote users. They also permitted collaborative work such as joint debugging of multi-author programs, an activity now associated with the Internet. These capabilities appear to be the earliest documented implementation of text messaging and were in use before electronic mail was developed for time-sharing systems.

The right of the beneficiary on the real estate units According to timeshare system (Comparative Study)

The right of the beneficiary on the real estate units According to timeshare system (Comparative Study)

From the Editor's Desk

This issue features several articles that give different perspectives on "modern computing" and how that concept evolves with emerging and retiring technologies. Specifically, the issue includes a discussion of the stored-program concept by Thomas Haigh, Mark Priestley, and Crispin Rope; a history of academic computer science degrees in Spain and the origins of Barcelona's School of Informatics by Jordi Fornes and Nestor Herran; a history of the fourth generation language (4GL) Nomad by Nicholas Rawlings; a rediscovery of the messaging capabilities in the SDC time-sharing system by David Hemmendinger; and a look at early commercial electronic distribution of software in the late 1970s by Zbigniew Stachniak.

Using HPC for teaching and learning bioinformatics software: Benefits and challenges

Background We present our work on using the XSEDE high-performance computing (HPC) network to support and facilitate hands-on bioinformatics tasks for participants of our Essentials of Next Generation Sequencing (NGS) workshop, as well as for students and other learners. In the summer of 2012, the University of Kentucky hosted the NGS workshop, attended by faculty and students from across the Commonwealth who were introduced to the laboratory and bioinformatic components of next-generation sequencing and sequence analysis. Participants used next-generation technology to sequence real genetic material, then used a variety of bioinformatics software tools to assemble those sequences, compare and align them to other sequences, predict genes, and visualize the genome. Due to the success of the 2012 workshop, the second workshop, planned for this summer, is expected to be larger in scale and to include even more participants. It will furthermore include several additional bioinformatics tools and tasks. Since participants will be simultaneously running intensive bioinformatics computing tasks, the resources required will exceed the capacity of the single twelve-core server used to support the workshop last year. One particular resource that appears promising to meet our intensive computational needs is the XSEDE grid computing network, a follow-on to the TeraGrid project designed specifically for “e-Science” and scientific computing. Many of the systems in the XSEDE network already support some of the software used within our workshop; however, many of the programs we will demonstrate have not previously been installed on tested on the XSEDE network. We will describe our experiences porting these applications to, and deploying them on, XSEDE. We will also discuss the challenges that the HPC approach presents for teaching and learning, particularly the complexities of navigating between time-sharing systems and remote job scheduling.

Dual-wavelength laser speckle imaging to simultaneously access blood flow, blood volume, and oxygenation using a color CCD camera

We developed a dual-wavelength laser speckle imaging system using a single industrial-grade color CCD camera with Bayer filters to simultaneously image changes in blood flow, blood volume, and oxygenation. One frame of a color image recorded with dual-wavelength laser illumination provides not only the intensity fluctuation of the speckle pattern, but also the dual-wavelength optical reflectance signal. The method was validated using a tissue phantom and cuff ischemia experiments in the human arm. This system achieves complete time synchronization, unlike conventional time-sharing systems. Compared with a multicamera system, it also avoids the problem of image registration and can be less expensive.

Performance Tuning Towards a KVM-based Embedded Real-time Virtualization System

Virtualization is a fundamental component in cloud computing because it provides numerous guest VM transparent services, such as live migration, high availability, rapid checkpoint, etc. Utilizing virtualization technology to combine real-time operating system (RTOS) and off-the-shelf time-sharing general purpose operating system (GPOS) is attracting much more interest recently. Such combination has the potential to provide a large application base, and to guarantee timely deterministic response to real-time applications, yet there remain some issues, such as responsiveness of RTOS running on top of a virtual machine (VM), system performance and CPU resource utilization rate, etc. In this paper we propose an embedded real-time virtualization architecture based on Kernel- Based Virtual Machine (KVM), in which VxWorks and Linux are combined together. We then analyze and evaluate how KVM influences the interrupt-response times of VxWorks as a guest operating system. By applying several real-time performance tuning methods on the host Linux, we will show that sub-millisecond interrupt response latency can be achieved on the guest VxWorks. Furthermore, we also find out that prioritization tuning results in waste of CPU resources when RTOS is not executing real-time tasks, so we design a dynamic scheduling mechanism--co-scheduling to improve system performance. Experimental results with SPEC2000 and bonnie 1.4 load, show that this new architecture tuned by CPU shielding, prioritization and co-scheduling, can achieve better real-time responsiveness and system performance.

David Barron: a life in software, 1935–2012

David Barron: a life in software, 1935–2012

Nd:YAG脉冲激光器双光路输出分时控制系统的设计

On account of the characteristics of laser double-pass processing,a Nd∶ YAG pulsed laser is chosen as the light source,and a laser time-sharing control system for double-pass outputs is developed.A concrete implemented project for time-sharing spectral technology is put forward,the beam split device is designed to achieve time-sharing beam split,and the time-sharing control circuit is designed to control the device in real time.Then,system program procedure is determined.Finally,laser outputs from different ports in different time are obtained under keeping the output powers.In order to avoid fiber damaging because of the jittering from beam split device,black photographic paper is used to sample of facula.The result shows that the best delay time is 300 ms from changing the holophote position to laser output.This system can not only realize time-share multiplexing and dynamic spectral splitting,but also can satisfy the need of double-pass outputs.Furthermore,the system has a stronger expanding ability,and can provide the convenience for laser improvement and upgrade according to the laser processing condition in reality.

Central Computerized Automatic Fetal Heart Rate Diagnosis with a Rapid and Direct Alarm System

Aims: This study aimed to simplify fetal monitoring, reduce inter-observer differences and false-positive diag- nosis and monitor a large number of births simultaneously. Methods: Fetal signals from several births were transmitted to a central computer via local area network (LAN) or telemetry and analyzed using a multichannel timesharing system. Fe- tal heart rate (FHR) abnormalities were detected by using three programs: the experts' knowledge system, power spectral analysis and artificial neural network. Abnormal results were automatically communicated directly to the attending doc- tor. Instead of an FHR chart recorder, the original fetal signals were stored on the computer and re-processed on demand. Results: a maximal FHR score in the first stage of labor indicated a low Apgar score, and correlated with umbilical blood pH. The fetal distress index derived from the FHR score was three or more in cases of fetal acidosis. The neural network yielded probabilities of fetal outcome that coincided with the FHR score, and the neural index derived from these prob- abilities predicted fetal outcome. Pathological sinusoidal FHR and severe loss of FHR variability were automatically diagnosed by power spectral analysis. Perinatal mortality was 1.1 in 1.000 births, which was significantly lower using this central computerized system than the previous system, and no cases of cerebral palsy were reported 2 months after delivery. Conclusion: The central computerized automated fetal monitoring system improved fetal outcomes even in insti- tutions dealing with a large number of births.

Electronic Mail and Text Messaging in CTSS, 1965-1973

Applications from prior technologies are often reimplemented on new computing or communications platforms, and users sometimes don't realize that the applications have been recycled. For example, text messaging was available between computer users for years before its implementation on cell phones, and email has precursors before its implementation on the Internet. Noel Morris and author Tom Van Vleck implemented both an electronic mail command and a text messaging facility for the Massachusetts Institute of Technology's Compatible Time-Sharing System (CTSS) in 1965. This new ability encouraged users to share information in new ways.

Method for removing longitudinal chromatism in full color holographic projection system

Hologram, as a type of diffractive optical element, is sensitive to wavelength in the process of optoelectronic reconstruction. Due to the different wavelengths of three prime colors used in full color holographic projections, there are chromatisms which badly spoil the reconstructed image. The chromatisms are composed of transverse and longitudinal chromatisms. For a computer generated hologram, transverse chromatism can be compensated by resampling the object information. However, it becomes more complex for longitudinal chromatism. This paper analyzes how the image is reconstructed from the phase-type hologram in a holographic projection system and the causations of longitudinal chromatism. To remove it, this paper proposes loading a specially designed phase distribution on a phase-type hologram. The advantage of this method is that it can be achieved by computer calculation and without adding any hardware such as achromatic optical element. A time-sharing system for a full-color hologram projection is developed in this paper. Comparisons have been made between the reconstructed images with and without chromatism. The experimental result shows that the method is effective in removing longitudinal chromatism and the quality of the reconstructed image is improved.

Mean Approximate Formulas for GI/G/1 Processor-Sharing System

The processor-sharing (PS) rule arises as a natural paradigm in a variety of practical situations, including time-shared computer systems. Although there has been much work on Poisson-input queueing analysis for the PS rule, there have been few results for renewal-input GI/G/1 (PS) systems. We consider the GI/G/1 (PS) system to provide develop a two-moment approximation for the mean performance measures. We derive the relationship between the mean unfinished work and the conditional mean sojourn time for the GI/G/1 (PS) system. Using this relationship, we derive approximate formulas for the mean conditional sojourn time, mean sojourn time, and the mean number of customers in the GI/G/1 (PS) system. Numerical examples are presented to compare the approximation with exact and simulated results. We show that the proposed approximate formulas have good accuracy.

The German TR 440 Computer: Software and Its Development

The TR 440, a large-scale computer developed and manufactured by the German company AEG-Telefunken, was one of the first commercial time-sharing systems. This article focuses on the TR 440's software and software development between 1965 to 1974, describing the technical highlights and showing how the software development was managed, who was responsible for various parts, and how and why certain decisions were made.

External Characteristics of Computer Operations: Toward Large Conversational Time-Sharing Systems

In an historical overview of computer operations in scientific-technical environments from the second half of the 1950s to the mid-1960s, this article discusses the ways German universities and similar institutions initially used small computers. It reports on the emergence of high-level programming languages, the appearance and predominance of large batch-processing systems, and the arising efforts to reestablish a conversational mode of operations.