DSOS
Encyclopedia
DSOS was a real-time operating system
(sometimes referred to as an operating system
kernel) developed by Texas Instruments
' Geophysical Services division
(GSI) in the mid-1970s.
. They would collect data in likely spots around the world, process that data using high performance computers
, and produce analyses that guided oil companies toward promising sites for drilling.
Much of the oil being sought was to be found beneath the ocean, hence GSI maintained a fleet of ships to collect seismic data from remote regions of the world. In order to do this properly is was essential that the ships be navigated precisely - if you find evidence of oil, you can't just mark an "X" on a tree - the oil is thousands of feet below the ocean and you are typically hundreds of miles from land. But this was a decade or more before GPS existed, thus the processing load to keep an accurate picture of "where you are" was considerable.
The GEONAV systems, which used DSOS as their operating system, performed the required navigation and, in addition, collected, processed and stored the seismic data being received in real-time.
professor, Dennis Frailey, who insisted that an operating system was the solution to the problem at hand. In a sense the system lived up to its name, according to legend. Supposedly one of the ships hit an old WWII sea mine
off the coast of Egypt and sank while being navigated by GEONAV and DSOS.
were classic examples of "spaghetti code
" - complex masses of assembly language
software using all sorts of machine-dependent
tricks to achieve maximum performance.
DSOS ran on a Texas Instruments
980 minicomputer being used for marine navigation on GSI's fleet. DSOS was created to bring some order to the chaos that was typical of real-time system design at that time. The 980 was, for its time, a relatively powerful small computer that offered memory protection
and multiple-priority interrupt capabilities. DSOS was designed to exploit these features.
, task management and software interrupts, it used a clever scheme to assure appropriate real-time performance while providing many services previously uncommon in the real-time domain (such as an orderly way to communicate with external devices and computer operators, multitasking, maintenance of records, a disciplined form of inter-task communication, a reliable real-time clock
, memory protection, and debugging support). It remained in use for at least three decades and it demonstrated that, if well designed, an operating system can actually make a real-time system faster (and vastly more maintainable) than what had been typical before. Today, almost all real-time applications utilize operating systems of this type.
Real-time operating system
A real-time operating system is an operating system intended to serve real-time application requests.A key characteristic of a RTOS is the level of its consistency concerning the amount of time it takes to accept and complete an application's task; the variability is jitter...
(sometimes referred to as an operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
kernel) developed by Texas Instruments
Texas Instruments
Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...
' Geophysical Services division
Geophysical Service Incorporated
Geophysical Service Inc. was founded by John Clarence Karcher and Eugene McDermott in 1930 for the purpose of using refraction and reflection seismology to explore for petroleum deposits. It became one of the most successful seismic exploration contractors in the industry for many years...
(GSI) in the mid-1970s.
Background
The Geophysical Services division of Texas Instruments' main business was to utilize the latest technology to search for oilOil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
. They would collect data in likely spots around the world, process that data using high performance computers
Supercomputer
A supercomputer is a computer at the frontline of current processing capacity, particularly speed of calculation.Supercomputers are used for highly calculation-intensive tasks such as problems including quantum physics, weather forecasting, climate research, molecular modeling A supercomputer is a...
, and produce analyses that guided oil companies toward promising sites for drilling.
Much of the oil being sought was to be found beneath the ocean, hence GSI maintained a fleet of ships to collect seismic data from remote regions of the world. In order to do this properly is was essential that the ships be navigated precisely - if you find evidence of oil, you can't just mark an "X" on a tree - the oil is thousands of feet below the ocean and you are typically hundreds of miles from land. But this was a decade or more before GPS existed, thus the processing load to keep an accurate picture of "where you are" was considerable.
The GEONAV systems, which used DSOS as their operating system, performed the required navigation and, in addition, collected, processed and stored the seismic data being received in real-time.
Deep Six Operating System
The name "Deep Six Operating System" was the brainchild of Phil Ward (subsequently a world renowned GPS expert) who, at the time, was manager of the project and slightly skeptical of the computer scienceComputer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
professor, Dennis Frailey, who insisted that an operating system was the solution to the problem at hand. In a sense the system lived up to its name, according to legend. Supposedly one of the ships hit an old WWII sea mine
Naval mine
A naval mine is a self-contained explosive device placed in water to destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel...
off the coast of Egypt and sank while being navigated by GEONAV and DSOS.
Why an Operating System?
In the 1970s, most real-time applications did not use operating systems because the latter were perceived as adding too much overhead. Typical computers of the time had barely enough computing power to handle the tasks at hand. Moreover, most software of this type was written in assembly language. As a consequence, real-time systemsReal-time computing
In computer science, real-time computing , or reactive computing, is the study of hardware and software systems that are subject to a "real-time constraint"— e.g. operational deadlines from event to system response. Real-time programs must guarantee response within strict time constraints...
were classic examples of "spaghetti code
Spaghetti code
Spaghetti code is a pejorative term for source code that has a complex and tangled control structure, especially one using many GOTOs, exceptions, threads, or other "unstructured" branching constructs. It is named such because program flow tends to look like a bowl of spaghetti, i.e. twisted and...
" - complex masses of assembly language
Assembly language
An assembly language is a low-level programming language for computers, microprocessors, microcontrollers, and other programmable devices. It implements a symbolic representation of the machine codes and other constants needed to program a given CPU architecture...
software using all sorts of machine-dependent
Machine-dependent
Machine-dependent is a term for application software that runs only on a particular type of computer. Conversely, applications that run on a variety of different types of computers are called machine-independent, or cross-platform....
tricks to achieve maximum performance.
DSOS ran on a Texas Instruments
Texas Instruments
Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...
980 minicomputer being used for marine navigation on GSI's fleet. DSOS was created to bring some order to the chaos that was typical of real-time system design at that time. The 980 was, for its time, a relatively powerful small computer that offered memory protection
Memory protection
Memory protection is a way to control memory access rights on a computer, and is a part of most modern operating systems. The main purpose of memory protection is to prevent a process from accessing memory that has not been allocated to it. This prevents a bug within a process from affecting...
and multiple-priority interrupt capabilities. DSOS was designed to exploit these features.
Significance
DSOS (Frailey, 1975) was one of the pioneering efforts in real-time operating systems. Incorporating many of the principles being introduced at the time in mainframe systems, such as semaphores, memory managementMemory management
Memory management is the act of managing computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. This is critical to the computer system.Several...
, task management and software interrupts, it used a clever scheme to assure appropriate real-time performance while providing many services previously uncommon in the real-time domain (such as an orderly way to communicate with external devices and computer operators, multitasking, maintenance of records, a disciplined form of inter-task communication, a reliable real-time clock
Real-time clock
A real-time clock is a computer clock that keeps track of the current time. Although the term often refers to the devices in personal computers, servers and embedded systems, RTCs are present in almost any electronic device which needs to keep accurate time.-Terminology:The term is used to avoid...
, memory protection, and debugging support). It remained in use for at least three decades and it demonstrated that, if well designed, an operating system can actually make a real-time system faster (and vastly more maintainable) than what had been typical before. Today, almost all real-time applications utilize operating systems of this type.