Joint Program Office Research Articles

Extensions to the C programming language for enhanced fault detection

AbstractThe acceptance of the C programming language by academia and industry is partially responsible for the ‘software crisis’. The simple, trusting semantics of C mask many common faults, such as range violations, which would be detected and reported at run‐time by programs coded in a robust language such as Ada.Ada is a registered trademark of the U.S. Government (Ada Joint Program Office) This needlessly complicates the debugging of C programs. Although the assert macro lets programmers add run‐time consistency checks to their programs, the number of instantiations of this macro needed to make a C program robust makes it highly unlikely that any programmer could correctly perform the task. We make some unobtrusive extensions to the C language which support the efficient detection of faults at run‐time without reducing the readability of the source code. Examples of the extensions are automatic checking of error codes returned by library routines, constrained subtypes and detection of references to uninitialized and/or non‐existent array elements.

House adopts Landsat Bill

The National Landsat Policy Act (HR3614) was adopted by the House of Representatives on June 9. The bill, reported to the House by the Committee on Science, Space, and Technology, was introduced by chair George E. Brown (D‐Calif.) on October 23, 1991.HR3614 creates a new management structure for the Landsat program by establishing a Joint Program Office to manage the program instead of the Department of Commerce. Funding and management responsibilities would be shared equally between NASA and the Department of Defense, and with other agencies as determined by the president. The bill would also provide for the procurement of the next in a series of Landsat satellites. It pinpoints specific policy changes aimed at enhancing the program's value, particularly for global change and environmental research. Landsat data has been used for environmental management, oil and gas exploration, crop assessments, and deforestation monitoring.

Ada Gets Groomed for the Whole Spectrum of Real-Time Duties.

Ada is a high level language, designed for implementing large embedded systems. It became an ANSI standard in 1983 and in 1У88 the Ada .Joint Program Office established the ADA-9Х project for the revision of the /Vda standard. One of the specific areas addressed by the revision team deals with requirements posed by real-time applications and introduces a now building block for real-time Ada: the protected record. Protected records provide a low level data-oriented synchronization mechanism and are a primary support, for real-time systems. They can be used to efficiently program solutions for real-time problems such as mut ual exclusion, conditionally shared data, counting semaphores and signals. This paper compares two different approaches for the solution of a classical real-time problem: conditional critical regions. The first solution uses AdaJSd tasking and tin* second one uses Ada9X protected records .finally we will discuss the runt inte support and some implementation issues for protected records on multiprocessor target systems.

An Option for Mechanizing Integrated GPS/INS Solutions

The GPS Joint Program Office has directed the delivery of GPS user equipment incorporating standard hardware and software. The resulting package, RCVR-3A, is designed to provide specified navigation performance under a wide range of alternative avionics interface requirements and aircraft mission scenarios. However, various integration studies have demonstrated that some of the RCVR-3A's potential performance is not realized because of the software design compromises made to accommodate standardization requirements. This is particularly the case when GPS measurements are integrated with INS outputs in RCVR-3A INS-mode operation. Therefore, some integrators have chosen to mechanize an independent navigation filter in a host vehicle mission computer when their system requirements exceed the GPS specifications. An alternative approach is to provide custom tuning for the RCVR-3A navigation filter to improve the receiver's own estimates of velocity and platform alignment. This paper summarizes the results of studies indicating that filter tuning is a cost-effective approach for certain combinations of INS and aircraft mission requirements. The paper concludes with a discussion of alternative means of mechanizing the RCVR-3A retuning.

An overview of DOD-STD-1838A (proposed) the common APSE interface set: revision

A five-year effort under the Ada Joint Program Office has developed a proposed standard for a host system interface as seen by tools running in an Ada Programming Support Environment (APSE). Standardization of this interface as DOD-STD-1838A will have a number of desirable effects for the Department of Defense, including tool portability, tool integration, data transportability, encouragement of a market in portable tools, and better programmer productivity. As the capability of tools to communicate with each other is a central requirement in APSEs, the Common APSE Interface Set (CAIS) has paid particular attention to facilitate such communication in a host-independent fashion. CAIS incorporates a well-integrated set of concepts tuned to the needs of writers and users of integrated tool sets. This paper covers several of these concepts: • the entity management system used in place of a traditional filing system, • object typing with inheritance, • process control including atomic transactions, • access control and security, • input/output methods, • support for distributed resource control, and • facilities for inter-system data transport.

An overview of DOD-STD-1838A (proposed) the common APSE interface set: revision

A five-year effort under the Ada Joint Program Office has developed a proposed standard for a host system interface as seen by tools running in an Ada Programming Support Environment (APSE). Standardization of this interface as DOD-STD-1838A will have a number of desirable effects for the Department of Defense, including tool portability, tool integration, data transportability, encouragement of a market in portable tools, and better programmer productivity. As the capability of tools to communicate with each other is a central requirement in APSEs, the Common APSE Interface Set (CAIS) has paid particular attention to facilitate such communication in a host-independent fashion. CAIS incorporates a well-integrated set of concepts tuned to the needs of writers and users of integrated tool sets. This paper covers several of these concepts: • the entity management system used in place of a traditional filing system, • object typing with inheritance, • process control including atomic transactions, • access control and security, • input/output methods, • support for distributed resource control, and • facilities for inter-system data transport.

Software Technology for Adaptable, Reliable Systems (STARS) program management plan

Abstract : Software Technology for Adaptable, Reliable Systems, or STARS, is the Defense Department's program to achieve dramatic improvements in software quality and to mitigate runaway software costs. This management plan provides guidance for organization, responsibilities, and STARS Joint Program Office staffing. The mangement strategy includes an increased role for Service research laboratories in the fundamental technology efforts and establishes a strong industry leadership role in STARS technology development.

Investigation of the Potential Application of GPS for Precision Approaches

This paper investigates the potential of using GPS for precision approach landing operations. The issues addressed are accuracy, integrity, and coverage reliability. The results of the investigation show that GPS performance, as specified by the GPS Joint Program Office, does not presently satisfy precision approach requirements as specified by the International Civil Aviation Organization. Although the horizontal accuracy of GPS is within the requirement specified for a precision approach to 200 ft altitude above the runway, it is shown that GPS, even when operating in a differential mode, does not achieve the required vertical accuracy. Integrity and coverage reliability are also shown to require further improvement for GPS to be considered for use as a precision approach system.

V60 real-time operating system

This paper describes the requirements for 32-bit microprocessor real-time operating systems, design objectives and the implementation of the V60(∗)/V70(∗∗) Real-Time Operating System (RTOS) and its programming supports. (∗), (∗∗) V60 and V70 are trademarks of NEC Corporation. The V60/V70 RTOS is designed for NEC's 32-bit microprocessor series, V60 and V70. It provides real-time operation with a reliable task environment, a high-level intertask communication mechanism based on Ada(∗)'s rendezvous and fault tolerant capability. These functions are implemented efficiently using V60/V70's architectural feature, e.g. multiple virtual address space, ring level protection and context switching instructions. The RTOS is constructed from three separable modules, real-time kernel, file system and UNIX (∗∗) supervisor. This structure can cover a wide range of application from small embedded systems to large fault tolerant systems. A high-level language and system generation support tools are also provided to increase application program productivity. (∗) Ada is a registered trademark of U.S. Government, Ada Joint Program Office. (∗∗) UNIX is a trademark of AT&T Bell Laboratories.

Global Positioning System Differential Navigation Tests at the Yuma Proving Ground

The Global Positioning System (GPS) Joint Program Office has conducted the majority of user equipment testing at the U. S. Army Yuma Proving Ground (YPG), Yuma, Arizona. This paper briefly reviews the history of CPS testings at YPG, describes the major assets of the test range and presents the results of dynamic and static differential GPS tests conducted at YPG.

The Specification and Implementation of GKS Application Software in ADA (R)

AbstractOne of the most important uses of (interactive) computer graphics is as one of the tools available to a User Interface Management System (UIMS) for a variety of user‐computer environments (UCE). Typical UCEs in vogue are Programming Support Environments (PSE), Expert System Builders (ESB), Office Automation systems (OAS). This paper concentrates on the conceptual relationship that exists between the users on the one hand and computer systems on the other. Such relationships are to be seen in the context of specific application domains. The two standards, GKS and Ada, are chosen to be the background against which the argument for a Software Methodology based on the Abstract Data Type approach, is presented. This has significant implications for a GKS binding to Ada and the development of GKS application software written in Ada. A collection of colour models is considered in detail.Ada(R) is a registered trademark of the U.S. Government, Ada Joint Program Office.

Validation and language standards

The problem of certifying a programming language processor as conforming to a set of specifications is currently extending the reach of feasibility past the state of the art of computer science, except in some trivial cases. This white paper considers the problems which are currently confronting the Ada ∗∗ ∗∗ Ada is a registered trademark of the Ada Joint Program Office of the U.S. Dept. of Defense. Joint Program Office (AJPO) of the U.S. Department of Defense with respect to the enforcement of the trademark for Ada and the parallel activities towards establishing the Ada Language as an American National Standard.

Contemporary Cybernetics

A recent report by Patrick G. Skelly of the ACM Standards Committee outlines some of the reasons why the ACM has asked that the Programming Language Ada specification is not given American National Standard (ANSI) status at this time. The full text of the ACM position on Standardization of Ada, together with the re‐sponses from the U.S. Department of Defence Ada Joint Program Office (AJPO) is given in Communications of the ACM, 25, 2 (1982).

The educational issues confronting Ada (Panel Discussion)

Sponsored by the Department of Defense, Ada is a programming language that embodies and enforces many modern software methodologies. Thus, the introduction of the language gives the opportunity for improvements in software reliability, maintainability, and clarity. Ada also offers some unique educational challenges and opportunities, so this panel will focus on some of the requirements for industrial, graduate, and undergraduate Ada education. In particular, the panel will explore different teaching methodologies, and will share their experiences in teaching the language. Each panelist is actively involved in the Ada program, and has contributed to the development of an educational strategy for the Ada Joint Program Office.