Command Information Research Articles

Performance analysis of a peer-to-peer I/O architecture in video server environments

In the personal computing (PC) and workstation environments, more and more I/O adapters are becoming complete functional subsystems that are intelligent enough to handle I/O operations on their own without much intervention from the host processor. The IBM Subsystem Control Block (SCB) architecture has been defined to enhance the potential of these intelligent adapters by defining services and conventions that deliver command information and data to and from the adapters. The SCB architecture has two operating modes. The Locate Mode represents the conventional, interrupt-driven I/O protocol used in many current personal computers. The Move Mode embodies an advanced, peer-to-peer I/O protocol proposed for the next generation of personal computers. In this paper, we would like to discuss and present a performance analysis of the SCB architecture in typical video server environments. In particular, we study a video server capable of providing support for simultaneous MPEG-1 video streams to multiple clients on a 16-Mbps token-ring network. We also consider the performance impact of a hypothetical 100-Mbps token-ring technology on the video server performance.

A performance analysis of advanced I/O architectures for PC-based network file servers

In the personal computing and workstation environments, more and more I/O adapters are becoming complete functional subsystems that are intelligent enough to handle I/O operations on their own without much intervention from the host processor. The IBM Subsystem Control Block (SCB) architecture has been defined to enhance the potential of these intelligent adapters by defining services and conventions that deliver command information and data to and from the adapters. In recent years, a new storage architecture, the Redundant Array of Independent Disks (RAID), has been quickly gaining acceptance in the world of computing. In this paper, we would like to discuss critical system design issues that are important to the performance of a network file server. We then present a performance analysis of the SCB architecture and disk array technology in typical network file server environments based on personal computers (PCs). One of the key issues investigated in this paper is whether a disk array can outperform a group of disks (of same type, same data capacity, and same cost) operating independently, not in parallel as in a disk array.

Performance analysis of advanced I/O architectures for PC-based video servers

In the personal computing and workstation environments, more and more I/O adapters are becoming complete functional subsystems that are intelligent enough to handle I/O operations on their own without much intervention from the host processor. The IBM subsystem control block (SCB) architecture has been defined to enhance the potential of these intelligent adapters by defining services and conventions that deliver command information and data to and from the adapters. In recent years, a new storage architecture, the redundant array of independent disks (RAID), has been quickly gaining acceptance in the world of computing. In this paper, we discuss and present a performance analysis of the SCB architecture and disk array technology in typical video server environments. In particular, we would like to see whether a disk array can outperform a group of disks (of the same type, the same data capacity, and same cost) operating independently (not in parallel as in a disk array) in a video server environment where most disk I/O operations are large sequential reads.

Effect of Combat on Aircrew Subjective Readiness During Operations Desert Shield and Desert Storm

The Persian Gulf War provided a unique opportunity to collect data for examining aircrew work/rest cycles and operational tasking as they relate to aircrew readiness in a combat environment. For 4 consecutive weeks during Operations Desert Shield and Desert Storm, 18 A-6 (9 pilots, 9 bombardier/navigators) and 18 F-14 (10 pilots, 8 radar intercept officers) aircrew on board the USS America provided detailed daily activity data. Additional operational data and subjective reports of aircrew readiness (the amount of crew rest required before a combat mission could be flown) were obtained following each mission. Multiple-regression analysis indicated that flight duration, time of day that a flight occurred, number and order of flights in a day, and amount of sleep obtained 12 hr before flying aided in the prediction of aircrew combat readiness. These data provide valuable information for air wing commanders, senior mission planners, and air wing flight surgeons to consider when assessing aircrew readiness.

Packet-switched WANs: more with less

During Operation Desert Storm, the US military used a packet-switched wide area network (WAN) to support the Army Central Forces Command and Control Information System (AC2IS) for the first time. The lessons learned from the difficulties encountered connecting a digital computer network using tactical signaling and switching equipment are outlined. The communications support which was available in Saudi Arabia, the AC2IS WAN configuration, and the performance of the packet switches used in the network are described. Operational statistics of circuit performance are presented. >

Developing a command and control system in war

The Army Central Forces (ARCENT) Command and Control Information System (AC2IS) that provided Army level staff officers with a secure means to pass electronic messages quickly and transfer data files long distances is discussed. AC2IS allowed users to generate memos, charts, and spreadsheets on a personal computer or workstation and then transmit them to a remote destination error-free. The system combined special computer networking equipment with existing automation and communications equipment to connect users. AC2IS users in Saudi Arabia regularly communicated with other users in Saudi Arabia, the United States, and Germany. The equipment and architecture of AC2IS, the secure channels provided by AC2IS, the initial fielding and subsequent expansion of the system are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The missing link: computer-supported telephony

From an engineering viewpoint, the physical realisation of a computer-supported telephony application involves connecting a computer with a telephone system by a signalling or data link which supports a protocol to carry command and status information between the two systems. In principle, any computer can support the computer supported telephony (CST) protocol, and the telephone system may be a PABX, an automatic call distributor, a key system or any other telephone switch. Existing or new systems can be linked by CST. The author discusses applications of CST the main one being telemarketing. The technology to support CST is not very advanced. At the heart of a modern telephone system is a computer. What CST does is link that embedded computer to a less specialised one. This technology is discussed by the author. The role of CST within the wide telecommunications and IT environment is also discussed.

A Procedure for the Delimitation of Tasks in Chemical Process Control Hierarchies

A philosophy is described for the separation of seemingly large multlvariable control strategies into fundamental modules which supervise distinct tasks. These modules relate to each other by means of defined Inputs and Outputs. An Output of one module can be passed as one of the Inputs to some other module, establishing a command information flow through the hierarchy. A set of rules was developed which guided the authors in the definition of some 240 advanced control algorithms, to be implemented in a Distributed Control environment on an oil refinery. The method includes useful graphical representations, and lends itself to Database techniques for the control of design information.

Command, Control, Communications and Management Information Systems

Command, Control, Communications and Management Information Systems

Flight evaluation of pursuit displays for precision approach of powered-lift aircraft

Flight experiments with NASA Ames Research Center's quiet short-haul research aircraft evaluated the influence of pursuit displays on the ability of pilots to execute precision-instrument flight operations in the terminal area, particularly approaches to and landings on a short runway. The aircraft is a powered-lift, short-takeoff and landing configuration equipped with a modern digital fly-by-wire flight control system, a head-up display, and a color head-down display that make it possible to investigate control and display concepts for full-envelope, powered-lift operations. Flight-path-oriented displays that provide status and command information in a format with minimal clutter were investigated. The pilots could fly the aircraft with the precision associated with flight-director guidance and with a high degree of situation awareness. The primary benefits of this display concept were realized when the pilot was required to execute a complex transition and approach under instrument conditions and in the presence of a wide range of wind and turbulence conditions.

Laboratory MicroStar: A data-logging word processor for research on word processing

Research on word processing is currently the most popular single topic in the study ofhuman-computer interaction, in part because of Card, Moran, and Newell's (1983) powerful keystroke-level model of performance, which requires the logging of keystrokes and latencies. However, many potential researchers in this area are frustrated because of the unavailability of a data-logging word processor for the mM PC. Laboratory MicroStar is a word processor that logs the keystrokes and keystroke latencies of the user. It provides unobtrusive data logging of text entries, commands, and help requests for word-processing research in an mM PC environment. The program was made completely selfdocumenting so that we could log the user's help requests for command information or general information about the program, as well as the actual commands and text entries. Laboratory MicroStar was designed to perform the routine word-processing tasks of our users, such as the writing of term papers, theses, or personal correspondence. Laboratory Microstar was created from the program MicroStar, which is distributed as part of Borland International's Version 1.0 Editor ToolBox (Borland International, 1985). Its commands are largely a subset of the WordStar word-processing program distributed by MicroPro, and the source code is written in Version 3.0 Turbo Pascal with an occasional assembly-language subroutine. MicroStar, although it uses the same commands as does WordStar, is quite different. In the first place, it does not buffer text to disk, but instead edits memory-resident text only. Second, although it accepts WordStar commands from the keyboard, it also has a parallel system of pulldown menus, so that the user can completely bypass keyboard command entry. Finally, it is not a complete wordprocessing program as distributed by Borland; Borland's intent is that the user should modify MicroStar to add whatever additional features might be needed. For example, it is almost completely devoid of print-time formatting features, such as dot commands, double spacing, and so forth.

Somatotopic representation in inferior area 6 of the macaque monkey.

On the basis of its cytoarchitectonic and enzymatic properties area 6 of the macaque monkey can be subdivided into two large sectors: a superior sector lying medial to the spur of the arcuate sulcus (superior area 6 or F2) and an inferior sector lying lateral to it (inferior area 6). Inferior area 6 is constituted by two enzymatic areas: F4 and F5. In this study we investigated the somatotopic organization of inferior area 6 and the adjacent area 4 combining single-neuron recording and intracortical electrical microstimulation. We found that two separate movement representations exist in this region. The caudal one corresponds to area F1 (primary motor cortex), the rostral one to inferior area 6. The two representations are mirror images one of the other with the axioproximal movements being adjacently located. In the rostral map the proximal movements are mostly located in F4, the distal movements in F5. Neuronal properties indicate that the rostral map has characteristics that are more complex than the caudal map. We propose that the rostral map is involved in transforming visual information in motor commands. F4 should be involved in the control of arm movements based on the location of the objects in respect to the body, whereas F5 should play a role in the control of grasping movements on the basis of the size of the stimuli.

Army Command and Control Information Systems Requirements Definition

The process of developing Army command and control information systems has been less than totally successful in producing fielded systems. One critical but often neglected aspect of that process, the requirements definition phase, is discussed. It is argued that the dynamic, high-risk, stressful military decision environment has unique characteristics which make it difficult merely to adapt information systems from, for example, a business environment. It is further argued that, within the military, the Army in particular has special characteristics that complicate the requirements definition process. Finally, the total acquisition process, particularly the time taken by that process, is shown to work against effective requirements definition. A series of solutions to these problems are proposed within the context of the concept-based requirements system.

User behavior upon introduction of a network help system

An online help system, called ICNHELP, was implemented on the large Los Alamos Integrated Computing Network. Users from three different operating systems could quickly access summary information on network capabilities. Usage was monitored for a five-month period, and users were given the opportunity to comment online. There were three times as many accesses as users. Most users accessed ICNHELP to jog their memories about specific command information, but a high number used it as a browsing tool to learn about network capabilities. The study reveals that the user interface is important in user acceptance of an online user assistance tool, but the established patterns of user behavior and mode of advertising also strongly affect the success of the system.

An Optimal Control Methodology for Analyzing the Effects of Display Parameters on Performance and Workload in Manual Flight Control

An approach to the analysis of the effects of display parameters on manual control based on an optimal control model of the human operator and a related model for task interference is presented. The methodology allows one to predict the effects of changes in display variables on both performance and attentional demand or workload. The methodology is applied to vertical situation displays for STOL (short takeoff and landing) approach-to-landing. Both status displays and displays of command information are examined and compared in terms of approach success probability and workload requirements.

Flight Evaluation of Three-Dimensional Area Navigation for Jet Transport Noise Abatement

The NASA, working with American Airlines, has completed the first phase of research to evaluate the operational feasibility of two-segment approaches for noise abatement. For these tests, area navigation was used to establish the upper glide slope and an ILS was used to establish the lower. The flight director was modified to provide command information during the entire approach. Twenty-eight pilots representing the airlines, professional pilot associations, FAA, and NASA participated. With an ILS approach for comparison, the procedure gave a noise reduction of 18 EPNdB at the outer marker and 8 EPNdB 1.1 n. mi. from touchdown.

Evaluation of methods for the determination of factors inducing fatigue in man at work.

Abstract In the man-machine system man is exposed to the direct influence of various factors. Among the many factors, the influence of which is not insignificant, is the machine, i.e. its design characteristics in relation to the operator's effort. In machine tools research measurements have been made on elements for running the machine using position analysis, dynamic analysis, analysis of force for running the command elements, functional analysis and information analysis. The results of particular analyses point to the resolution of problems of the adaptation of the machine to the man thereby decreasing energy consumption by combining those solutions in same part. In this manner a completely redesigned programme can be made, the new version of which will reduce the consumption of energy and time for the task. In this way we get a machine design which can attain higher productivity with less effort by the man.

Man-Machine Considerations in System Design for All-Weather, Low-level Navigation

This paper is concerned with man-machine considerations in system design for low-level navigation. In particular, computer generation of command information and visual display presentation are described. Simulated results are presented which indicate that the pilot's ability to fly on a given route is improved with the roll command display.

Differential eyelid conditioning to stimuli that express a response-related command or convey reinforcement-related information

Either command words, BLINK and DON'T BLINK, or informing words, PUFF and NO PUFF, were used as differential conditioned stimuli with a corneal airpuff UCS. For half the Ss the stimuli expressed commands that were compatible with the appropriate CR or gave information which was congruent with the CS-UCS contingency, and for half the Ss the command was incompatible or the information incongruent. Effects of incompatibility and incongruity depended upon the topography of the S's eyelid CR! For Ss giving the gradual C form the CS-UCS reinforcement contingencies overcame effects of incompatible command or incongruent information, but for Ss giving the rapid, complete V form incompatibility or incongruity seriously disrupted the discrimination, suggesting that Vs have more difficulty than Cs in recording verbal information.

Navigation System Requirements for Supersonic Transport

This paper, based on an earlier one presented at the Eastbourne Convention in May 1964, discusses certain aspects of S.S.T. performance and its bearing on the design of the air navigation system and on the air traffic control system. The requirement is established for a navigation system capable of directing the S.S.T. at minimum economic penalty and within the limits imposed by air traffic control and sonic boom considerations. The system should also be able to determine estimated time of arrival, fuel remaining, and altitude for any randomly chosen point along the flight path; to derive the time of arrival at a particular altitude and, for a selected time of arrival at a chosen position and altitude, give the deceleration and other necessary command information.