1.
DOS
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None of these systems were officially named DOS, and indeed DOS is a general term for disk operating system. MS-DOS dominated the IBM PC compatible market between 1981 and 1995, and Microsoft Windows, still ran on top of it until about 2001, dozens of other operating systems also use the acronym DOS, including DOS/360 from 1966. Others are Apple DOS, Apple ProDOS, Atari DOS, Commodore DOS, TRSDOS, see List of DOS operating systems § Other operating systems. IBM PC DOS and its predecessor, 86-DOS, resembled Digital Researchs CP/M—the dominant disk operating system for 8-bit Intel 8080, DOS instead ran on Intel 8086 16-bit processors. Starting with MS-DOS1.28 and PC DOS2.0 the operating system incorporated various features inspired by Xenix, when IBM introduced the IBM PC, built with the Intel 8088 microprocessor, they needed an operating system. Seeking an 8088-compatible build of CP/M, IBM initially approached Microsoft CEO Bill Gates, IBM was sent to Digital Research, and a meeting was set up. However, the negotiations for the use of CP/M broke down, Digital Research wished to sell CP/M on a royalty basis, while IBM sought a single license. Digital Research founder Gary Kildall refused, and IBM withdrew, Gates in turn approached Seattle Computer Products. There, programmer Tim Paterson had developed a variant of CP/M-80, the system was initially named QDOS, before being made commercially available as 86-DOS. Microsoft purchased 86-DOS, allegedly for $50,000 and this became Microsoft Disk Operating System, MS-DOS, introduced in 1981. Within a year Microsoft licensed MS-DOS to over 70 other companies, Microsoft later required the use of the MS-DOS name, with the exception of the IBM variant. IBM continued to develop their version, PC DOS, for the IBM PC, Digital Research became aware that an operating system similar to CP/M was being sold by IBM, and threatened legal action. IBM responded by offering an agreement, they would give PC consumers a choice of PC DOS or CP/M-86, side-by-side, CP/M cost almost $200 more than PC DOS, and sales were low. CP/M faded, with MS-DOS and PC DOS becoming the operating system for PCs. Microsoft originally sold MS-DOS only to original equipment manufacturers, one major reason for this was that not all early PCs were 100% IBM PC compatible. DOS was structured such that there was a separation between the specific device driver code and the DOS kernel. Microsoft provided an OEM Adaptation Kit which allowed OEMs to customize the device driver code to their particular system, by the early 1990s, most PCs adhered to IBM PC standards so Microsoft began selling MS-DOS in retail with MS-DOS5.0. In the mid-1980s Microsoft developed a version of DOS
2.
Software developer
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A software developer is a person concerned with facets of the software development process, including the research, design, programming, and testing of computer software. Other job titles which are used with similar meanings are programmer, software analyst. According to developer Eric Sink, the differences between system design, software development, and programming are more apparent, even more so that developers become systems architects, those who design the multi-leveled architecture or component interactions of a large software system. In a large company, there may be employees whose sole responsibility consists of one of the phases above. In smaller development environments, a few people or even an individual might handle the complete process. The word software was coined as a prank as early as 1953, before this time, computers were programmed either by customers, or the few commercial computer vendors of the time, such as UNIVAC and IBM. The first company founded to provide products and services was Computer Usage Company in 1955. The software industry expanded in the early 1960s, almost immediately after computers were first sold in mass-produced quantities, universities, government, and business customers created a demand for software. Many of these programs were written in-house by full-time staff programmers, some were distributed freely between users of a particular machine for no charge. Others were done on a basis, and other firms such as Computer Sciences Corporation started to grow. The computer/hardware makers started bundling operating systems, systems software and programming environments with their machines, new software was built for microcomputers, so other manufacturers including IBM, followed DECs example quickly, resulting in the IBM AS/400 amongst others. The industry expanded greatly with the rise of the computer in the mid-1970s. In the following years, it created a growing market for games, applications. DOS, Microsofts first operating system product, was the dominant operating system at the time, by 2014 the role of cloud developer had been defined, in this context, one definition of a developer in general was published, Developers make software for the world to use. The job of a developer is to crank out code -- fresh code for new products, code fixes for maintenance, code for business logic, bus factor Software Developer description from the US Department of Labor
3.
Microsoft
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Its best known software products are the Microsoft Windows line of operating systems, Microsoft Office office suite, and Internet Explorer and Edge web browsers. Its flagship hardware products are the Xbox video game consoles and the Microsoft Surface tablet lineup, as of 2016, it was the worlds largest software maker by revenue, and one of the worlds most valuable companies. Microsoft was founded by Paul Allen and Bill Gates on April 4,1975, to develop and it rose to dominate the personal computer operating system market with MS-DOS in the mid-1980s, followed by Microsoft Windows. The companys 1986 initial public offering, and subsequent rise in its share price, since the 1990s, it has increasingly diversified from the operating system market and has made a number of corporate acquisitions. In May 2011, Microsoft acquired Skype Technologies for $8.5 billion, in June 2012, Microsoft entered the personal computer production market for the first time, with the launch of the Microsoft Surface, a line of tablet computers. The word Microsoft is a portmanteau of microcomputer and software, Paul Allen and Bill Gates, childhood friends with a passion for computer programming, sought to make a successful business utilizing their shared skills. In 1972 they founded their first company, named Traf-O-Data, which offered a computer that tracked and analyzed automobile traffic data. Allen went on to pursue a degree in science at Washington State University. The January 1975 issue of Popular Electronics featured Micro Instrumentation and Telemetry Systemss Altair 8800 microcomputer, Allen suggested that they could program a BASIC interpreter for the device, after a call from Gates claiming to have a working interpreter, MITS requested a demonstration. Since they didnt actually have one, Allen worked on a simulator for the Altair while Gates developed the interpreter and they officially established Microsoft on April 4,1975, with Gates as the CEO. Allen came up with the name of Micro-Soft, as recounted in a 1995 Fortune magazine article. In August 1977 the company formed an agreement with ASCII Magazine in Japan, resulting in its first international office, the company moved to a new home in Bellevue, Washington in January 1979. Microsoft entered the OS business in 1980 with its own version of Unix, however, it was MS-DOS that solidified the companys dominance. For this deal, Microsoft purchased a CP/M clone called 86-DOS from Seattle Computer Products, branding it as MS-DOS, following the release of the IBM PC in August 1981, Microsoft retained ownership of MS-DOS. Since IBM copyrighted the IBM PC BIOS, other companies had to engineer it in order for non-IBM hardware to run as IBM PC compatibles. Due to various factors, such as MS-DOSs available software selection, the company expanded into new markets with the release of the Microsoft Mouse in 1983, as well as with a publishing division named Microsoft Press. Paul Allen resigned from Microsoft in 1983 after developing Hodgkins disease, while jointly developing a new OS with IBM in 1984, OS/2, Microsoft released Microsoft Windows, a graphical extension for MS-DOS, on November 20,1985. Once Microsoft informed IBM of NT, the OS/2 partnership deteriorated, in 1990, Microsoft introduced its office suite, Microsoft Office
4.
Programming language
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A programming language is a formal computer language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to programs to control the behavior of a machine or to express algorithms. From the early 1800s, programs were used to direct the behavior of such as Jacquard looms. Thousands of different programming languages have created, mainly in the computer field. Many programming languages require computation to be specified in an imperative form while other languages use forms of program specification such as the declarative form. The description of a language is usually split into the two components of syntax and semantics. Some languages are defined by a document while other languages have a dominant implementation that is treated as a reference. Some languages have both, with the language defined by a standard and extensions taken from the dominant implementation being common. A programming language is a notation for writing programs, which are specifications of a computation or algorithm, some, but not all, authors restrict the term programming language to those languages that can express all possible algorithms. For example, PostScript programs are created by another program to control a computer printer or display. More generally, a language may describe computation on some, possibly abstract. It is generally accepted that a specification for a programming language includes a description, possibly idealized. In most practical contexts, a programming language involves a computer, consequently, abstractions Programming languages usually contain abstractions for defining and manipulating data structures or controlling the flow of execution. Expressive power The theory of computation classifies languages by the computations they are capable of expressing, all Turing complete languages can implement the same set of algorithms. ANSI/ISO SQL-92 and Charity are examples of languages that are not Turing complete, markup languages like XML, HTML, or troff, which define structured data, are not usually considered programming languages. Programming languages may, however, share the syntax with markup languages if a computational semantics is defined, XSLT, for example, is a Turing complete XML dialect. Moreover, LaTeX, which is used for structuring documents. The term computer language is used interchangeably with programming language
5.
Assembly language
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Each assembly language is specific to a particular computer architecture. In contrast, most high-level programming languages are generally portable across multiple architectures, Assembly language may also be called symbolic machine code. Assembly language is converted into machine code by a utility program referred to as an assembler. The conversion process is referred to as assembly, or assembling the source code, Assembly time is the computational step where an assembler is run. Assembly language uses a mnemonic to represent each low-level machine instruction or opcode, typically also each architectural register, flag, depending on the architecture, these elements may also be combined for specific instructions or addressing modes using offsets or other data as well as fixed addresses. Many assemblers offer additional mechanisms to facilitate development, to control the assembly process. A macro assembler includes a facility so that assembly language text can be represented by a name. A cross assembler is an assembler that is run on a computer or operating system of a different type from the system on which the code is to run. Cross-assembling facilitates the development of programs for systems that do not have the resources to support software development, a microassembler is a program that helps prepare a microprogram, called firmware, to control the low level operation of a computer. A meta-assembler is a used in some circles for a program that accepts the syntactic and semantic description of an assembly language. An assembler program creates object code by translating combinations of mnemonics and syntax for operations and this representation typically includes an operation code as well as other control bits and data. The assembler also calculates constant expressions and resolves symbolic names for memory locations, the use of symbolic references is a key feature of assemblers, saving tedious calculations and manual address updates after program modifications. Most assemblers also include facilities for performing textual substitution – e. g. to generate common short sequences of instructions as inline. Some assemblers may also be able to some simple types of instruction set-specific optimizations. One concrete example of this may be the ubiquitous x86 assemblers from various vendors, most of them are able to perform jump-instruction replacements in any number of passes, on request. Like early programming languages such as Fortran, Algol, Cobol and Lisp, assemblers have been available since the 1950s, however, assemblers came first as they are far simpler to write than compilers for high-level languages. There may be several assemblers with different syntax for a particular CPU or instruction set architecture, despite different appearances, different syntactic forms generally generate the same numeric machine code, see further below. A single assembler may also have different modes in order to support variations in syntactic forms as well as their exact semantic interpretations, there are two types of assemblers based on how many passes through the source are needed to produce the executable program
6.
Open-source software
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Open-source software may be developed in a collaborative public manner. According to scientists who studied it, open-source software is a prominent example of open collaboration, a 2008 report by the Standish Group states that adoption of open-source software models has resulted in savings of about $60 billion per year to consumers. In the early days of computing, programmers and developers shared software in order to learn from each other, eventually the open source notion moved to the way side of commercialization of software in the years 1970-1980. In 1997, Eric Raymond published The Cathedral and the Bazaar and this source code subsequently became the basis behind SeaMonkey, Mozilla Firefox, Thunderbird and KompoZer. Netscapes act prompted Raymond and others to look into how to bring the Free Software Foundations free software ideas, the new term they chose was open source, which was soon adopted by Bruce Perens, publisher Tim OReilly, Linus Torvalds, and others. The Open Source Initiative was founded in February 1998 to encourage use of the new term, a Microsoft executive publicly stated in 2001 that open source is an intellectual property destroyer. I cant imagine something that could be worse than this for the software business, IBM, Oracle, Google and State Farm are just a few of the companies with a serious public stake in todays competitive open-source market. There has been a significant shift in the corporate philosophy concerning the development of FOSS, the free software movement was launched in 1983. In 1998, a group of individuals advocated that the free software should be replaced by open-source software as an expression which is less ambiguous. Software developers may want to publish their software with an open-source license, the Open Source Definition, notably, presents an open-source philosophy, and further defines the terms of usage, modification and redistribution of open-source software. Software licenses grant rights to users which would otherwise be reserved by law to the copyright holder. Several open-source software licenses have qualified within the boundaries of the Open Source Definition, the open source label came out of a strategy session held on April 7,1998 in Palo Alto in reaction to Netscapes January 1998 announcement of a source code release for Navigator. They used the opportunity before the release of Navigators source code to clarify a potential confusion caused by the ambiguity of the free in English. Many people claimed that the birth of the Internet, since 1969, started the open source movement, the Free Software Foundation, started in 1985, intended the word free to mean freedom to distribute and not freedom from cost. Since a great deal of free software already was free of charge, such software became associated with zero cost. The Open Source Initiative was formed in February 1998 by Eric Raymond and they sought to bring a higher profile to the practical benefits of freely available source code, and they wanted to bring major software businesses and other high-tech industries into open source. Perens attempted to open source as a service mark for the OSI. The Open Source Initiatives definition is recognized by governments internationally as the standard or de facto definition, OSI uses The Open Source Definition to determine whether it considers a software license open source
7.
Software release life cycle
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Usage of the alpha/beta test terminology originated at IBM. As long ago as the 1950s, IBM used similar terminology for their hardware development, a test was the verification of a new product before public announcement. B test was the verification before releasing the product to be manufactured, C test was the final test before general availability of the product. Martin Belsky, a manager on some of IBMs earlier software projects claimed to have invented the terminology, IBM dropped the alpha/beta terminology during the 1960s, but by then it had received fairly wide notice. The usage of beta test to refer to testing done by customers was not done in IBM, rather, IBM used the term field test. Pre-alpha refers to all activities performed during the project before formal testing. These activities can include requirements analysis, software design, software development, in typical open source development, there are several types of pre-alpha versions. Milestone versions include specific sets of functions and are released as soon as the functionality is complete, the alpha phase of the release life cycle is the first phase to begin software testing. In this phase, developers generally test the software using white-box techniques, additional validation is then performed using black-box or gray-box techniques, by another testing team. Moving to black-box testing inside the organization is known as alpha release, alpha software can be unstable and could cause crashes or data loss. Alpha software may not contain all of the features that are planned for the final version, in general, external availability of alpha software is uncommon in proprietary software, while open source software often has publicly available alpha versions. The alpha phase usually ends with a freeze, indicating that no more features will be added to the software. At this time, the software is said to be feature complete, Beta, named after the second letter of the Greek alphabet, is the software development phase following alpha. Software in the stage is also known as betaware. Beta phase generally begins when the software is complete but likely to contain a number of known or unknown bugs. Software in the phase will generally have many more bugs in it than completed software, as well as speed/performance issues. The focus of beta testing is reducing impacts to users, often incorporating usability testing, the process of delivering a beta version to the users is called beta release and this is typically the first time that the software is available outside of the organization that developed it. Beta version software is useful for demonstrations and previews within an organization
8.
Package manager
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A package manager deals with packages, distributions of software and data in archive files. Packages contain metadata, such as the name, description of its purpose, version number, vendor, checksum. Upon installation, metadata is stored in a package database. Package managers typically maintain a database of software dependencies and version information to prevent software mismatches and they work closely with software repositories, binary repository managers, and app stores. Package managers are designed to eliminate the need for manual installs, a software package is an archive file containing a computer program as well as necessary metadata for its deployment. The computer program can be in source code that has to be compiled, Package metadata include package description, package version, and dependencies. Package managers are charged with the task of finding, installing, maintaining or uninstalling software packages upon the users command, in these systems, complex relationships between different packages requiring different versions of libraries results in a challenge colloquially known as dependency hell. On Microsoft Windows systems, this is also called DLL hell when working with dynamically linked libraries, good package management is vital on these systems. System administrators may install and maintain software using other than package management software. For example, an administrator may download unpackaged source code, compile it. This may cause the state of the system to fall out of synchronization with the state of the package managers database. The local administrator will be required to take measures, such as manually managing some dependencies or integrating the changes into the package manager. There are tools available to ensure that locally compiled packages are integrated with the package management, particularly troublesome with software upgrades are upgrades of configuration files. There are exceptions to this that usually apply to kernel configuration, problems can be caused if the format of configuration files changes. For instance, if the old configuration file does not explicitly disable new options that should be disabled, some package managers, such as Debians dpkg, allow configuration during installation. In other situations, it is desirable to install packages with the configuration and then overwrite this configuration, for instance. This kind of pre-configured installation is also supported by dpkg, to give users more control over the kinds of software that they are allowing to be installed on their system, software is often downloaded from a number of software repositories. This process is called version pinning
9.
X86
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X86 is a family of backward-compatible instruction set architectures based on the Intel 8086 CPU and its Intel 8088 variant. The term x86 came into being because the names of several successors to Intels 8086 processor end in 86, many additions and extensions have been added to the x86 instruction set over the years, almost consistently with full backward compatibility. The architecture has been implemented in processors from Intel, Cyrix, AMD, VIA and many companies, there are also open implementations. In the 1980s and early 1990s, when the 8088 and 80286 were still in common use, today, however, x86 usually implies a binary compatibility also with the 32-bit instruction set of the 80386. An 8086 system, including such as 8087 and 8089. There were also terms iRMX, iSBC, and iSBX – all together under the heading Microsystem 80, however, this naming scheme was quite temporary, lasting for a few years during the early 1980s. Today, x86 is ubiquitous in both stationary and portable computers, and is also used in midrange computers, workstations, servers. A large amount of software, including operating systems such as DOS, Windows, Linux, BSD, Solaris and macOS, functions with x86-based hardware. There have been attempts, including by Intel itself, to end the market dominance of the inelegant x86 architecture designed directly from the first simple 8-bit microprocessors. Examples of this are the iAPX432, the Intel 960, Intel 860, however, the continuous refinement of x86 microarchitectures, circuitry and semiconductor manufacturing would make it hard to replace x86 in many segments. The table below lists processor models and model series implementing variations of the x86 instruction set, each line item is characterized by significantly improved or commercially successful processor microarchitecture designs. Such x86 implementations are seldom simple copies but often employ different internal microarchitectures as well as different solutions at the electronic, quite naturally, early compatible microprocessors were 16-bit, while 32-bit designs were developed much later. For the personal computer market, real quantities started to appear around 1990 with i386 and i486 compatible processors, other companies, which designed or manufactured x86 or x87 processors, include ITT Corporation, National Semiconductor, ULSI System Technology, and Weitek. Some early versions of these microprocessors had heat dissipation problems, AMD later managed to establish itself as a serious contender with the K6 set of processors, which gave way to the very successful Athlon and Opteron. There were also other contenders, such as Centaur Technology, Rise Technology, VIA Technologies energy efficient C3 and C7 processors, which were designed by the Centaur company, have been sold for many years. Centaurs newest design, the VIA Nano, is their first processor with superscalar and it was, perhaps interestingly, introduced at about the same time as Intels first in-order processor since the P5 Pentium, the Intel Atom. The instruction set architecture has twice been extended to a word size. In 1999-2003, AMD extended this 32-bit architecture to 64 bits and referred to it as x86-64 in early documents, Intel soon adopted AMDs architectural extensions under the name IA-32e, later using the name EM64T and finally using Intel 64
10.
Kernel (operating system)
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The kernel is a computer program that is the core of a computers operating system, with complete control over everything in the system. It is the first program loaded on start-up and it handles the rest of start-up as well as input/output requests from software, translating them into data-processing instructions for the central processing unit. It handles memory and peripherals like keyboards, monitors, printers, the critical code of the kernel is usually loaded into a protected area of memory, which prevents it from being overwritten by applications or other, more minor parts of the operating system. The kernel performs its tasks, such as running processes and handling interrupts, in contrast, everything a user does is in user space, writing text in a text editor, running programs in a GUI, etc. This separation prevents user data and kernel data from interfering with other and causing instability. The kernels interface is an abstraction layer. When a process makes requests of the kernel, it is called a system call, Kernel designs differ in how they manage these system calls and resources. A monolithic kernel runs all the operating instructions in the same address space. A microkernel runs most processes in space, for modularity. The kernel takes responsibility for deciding at any time which of the running programs should be allocated to the processor or processors. Random-access memory Random-access memory is used to both program instructions and data. Typically, both need to be present in memory in order for a program to execute, often multiple programs will want access to memory, frequently demanding more memory than the computer has available. The kernel is responsible for deciding which memory each process can use, input/output devices I/O devices include such peripherals as keyboards, mice, disk drives, printers, network adapters, and display devices. The kernel allocates requests from applications to perform I/O to an appropriate device, key aspects necessary in resource management are the definition of an execution domain and the protection mechanism used to mediate the accesses to the resources within a domain. Kernels also usually provide methods for synchronization and communication between processes called inter-process communication, finally, a kernel must provide running programs with a method to make requests to access these facilities. The kernel has full access to the memory and must allow processes to safely access this memory as they require it. Often the first step in doing this is virtual addressing, usually achieved by paging and/or segmentation, virtual addressing allows the kernel to make a given physical address appear to be another address, the virtual address. This allows every program to behave as if it is the one running
11.
Monolithic kernel
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A monolithic kernel is an operating system architecture where the entire operating system is working in kernel space and is alone in supervisor mode. The monolithic model differs from other operating system architectures in that it defines a high-level virtual interface over computer hardware. A set of primitives or system calls implement all operating system such as process management, concurrency. Device drivers can be added to the kernel as modules and this modularity of the operating system is at the binary level and not at the architecture level. Modular monolithic operating systems are not to be confused with the level of modularity inherent in Server-Client operating systems which use microkernels. Practically speaking, dynamically loading modules is simply a more flexible way of handling the operating system image at runtime — as opposed to rebooting with a different operating system image, the modules allow easy extension of the operating systems capabilities as required. Dynamically loadable modules incur a small overhead when compared to building the module into the system image. Namely, an unloaded module need not be stored in random access memory
12.
User interface
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The user interface, in the industrial design field of human–computer interaction, is the space where interactions between humans and machines occur. Examples of this concept of user interfaces include the interactive aspects of computer operating systems, hand tools, heavy machinery operator controls. The design considerations applicable when creating user interfaces are related to or involve such disciplines as ergonomics and psychology. Generally, the goal of user interface design is to produce a user interface makes it easy, efficient. This generally means that the needs to provide minimal input to achieve the desired output. Other terms for user interface are man–machine interface and when the machine in question is a computer human–computer interface, the user interface or human–machine interface is the part of the machine that handles the human–machine interaction. Membrane switches, rubber keypads and touchscreens are examples of the part of the Human Machine Interface which we can see. In complex systems, the interface is typically computerized. The term human–computer interface refers to this kind of system, in the context of computing the term typically extends as well to the software dedicated to control the physical elements used for human-computer interaction. The engineering of the interfaces is enhanced by considering ergonomics. The corresponding disciplines are human factors engineering and usability engineering, which is part of systems engineering, tools used for incorporating human factors in the interface design are developed based on knowledge of computer science, such as computer graphics, operating systems, programming languages. Nowadays, we use the graphical user interface for human–machine interface on computers. There is a difference between a user interface and an interface or a human–machine interface. A human-machine interface is typically local to one machine or piece of equipment, an operator interface is the interface method by which multiple equipment that are linked by a host control system is accessed or controlled. The system may expose several user interfaces to serve different kinds of users, for example, a computerized library database might provide two user interfaces, one for library patrons and the other for library personnel. The user interface of a system, a vehicle or an industrial installation is sometimes referred to as the human–machine interface. HMI is a modification of the original term MMI, in practice, the abbreviation MMI is still frequently used although some may claim that MMI stands for something different now. Another abbreviation is HCI, but is commonly used for human–computer interaction
13.
Command-line interface
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A program which handles the interface is called a command language interpreter or shell. The interface is implemented with a command line shell, which is a program that accepts commands as text input. Command-line interfaces to computer operating systems are widely used by casual computer users. Alternatives to the line include, but are not limited to text user interface menus, keyboard shortcuts. Examples of this include the Windows versions 1,2,3,3.1, and 3.11, DosShell, and Mouse Systems PowerPanel. Command-line interfaces are preferred by more advanced computer users, as they often provide a more concise. Programs with command-line interfaces are generally easier to automate via scripting, a program that implements such a text interface is often called a command-line interpreter, command processor or shell. Under most operating systems, it is possible to replace the shell program with alternatives, examples include 4DOS for DOS, 4OS2 for OS/2. For example, the default Windows GUI is a program named EXPLORER. EXE. These programs are shells, but not CLIs, application programs may also have command line interfaces. When a program is launched from an OS command line shell, interactive command line sessions, After launch, a program may provide an operator with an independent means to enter commands in the form of text. OS inter-process communication, Most operating systems support means of inter-process communication, Command lines from client processes may be redirected to a CLI program by one of these methods. Some applications support only a CLI, presenting a CLI prompt to the user, Some examples of CLI-only applications are, DEBUG Diskpart Ed Edlin Fdisk Ping Some computer programs support both a CLI and a GUI. In some cases, a GUI is simply a wrapper around a separate CLI executable file, in other cases, a program may provide a CLI as an optional alternative to its GUI. CLIs and GUIs often support different functionality, for example, all features of MATLAB, a numerical analysis computer program, are available via the CLI, whereas the MATLAB GUI exposes only a subset of features. The early Sierra games, like the first three Kings Quest games, used commands from a command line to move the character around in the graphic window. Early computer systems often used teleprinter machines as the means of interaction with a human operator, the computer became one end of the human-to-human teleprinter model. So instead of a human communicating with another human over a teleprinter, in time, the actual mechanical teleprinter was replaced by a glass tty, and then by a smart terminal
14.
Text-based user interface
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Text-based user interface, also called textual user interface or terminal user interface, is a retronym coined sometime after the invention of graphical user interfaces. TUIs display computer graphics in text mode, an advanced TUI may, like GUIs, use the entire screen area and accept mouse and other inputs. From text applications point of view, a screen can belong to one of three types, A genuine text mode display, controlled by a video adapter or the central processor itself. This is a condition for a locally running application on various types of personal computers. If not deterred by the system, a smart program may exploit the full power of a hardware text mode. Examples are xterm for X Window System and win32 console for Microsoft Windows and this usually supports programs which expect a real text mode display, but may run considerably slower. Certain functions of a text mode, such as an own font uploading. The communication capabilities usually become reduced to a line or its emulation, possibly with few ioctls as an out-of-band channel in such cases as Telnet. This is the worst case, because software restrictions hinder the use of capabilities of a display device. Under Linux and other Unix-like systems, a program easily accommodates to any of the three cases because the same interface controls the display and keyboard, also, specialized programming libraries help to output the text in a way appropriate to the given display device and interface to it. See below for a comparison to Windows, american National Standards Institute standard ANSI X3.64 defines a standard set of escape sequences that can be used to drive terminals to create TUIs. Escape sequences may be supported for all three mentioned in the above section, allowing random cursor movements and color changes. However, not all follow this standard, and many non-compatible. However, programmers soon learned that writing data directly to the buffer was far faster and simpler to program. This change in programming resulted in many DOS TUI programs. The win32 console environment is notorious for its emulation of certain EGA/VGA text mode features, particularly a random access to the text buffer, even if the application runs in a window. On the other hand, programs running under Windows have much control of the display and keyboard than Linux and DOS programs can have. Most often those used a blue background for the main screen, with white or yellow characters
15.
Software license
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A software license is a legal instrument governing the use or redistribution of software. Under United States copyright law all software is copyright protected, in code as also object code form. The only exception is software in the public domain, most distributed software can be categorized according to its license type. Two common categories for software under copyright law, and therefore with licenses which grant the licensee specific rights, are proprietary software and free, unlicensed software outside the copyright protection is either public domain software or software which is non-distributed, non-licensed and handled as internal business trade secret. Contrary to popular belief, distributed unlicensed software is copyright protected. Examples for this are unauthorized software leaks or software projects which are placed on public software repositories like GitHub without specified license. As voluntarily handing software into the domain is problematic in some international law domains, there are also licenses granting PD-like rights. Therefore, the owner of a copy of software is legally entitled to use that copy of software. Hence, if the end-user of software is the owner of the respective copy, as many proprietary licenses only enumerate the rights that the user already has under 17 U. S. C. §117, and yet proclaim to take away from the user. Proprietary software licenses often proclaim to give software publishers more control over the way their software is used by keeping ownership of each copy of software with the software publisher. The form of the relationship if it is a lease or a purchase, for example UMG v. Augusto or Vernor v. Autodesk. The ownership of goods, like software applications and video games, is challenged by licensed. The Swiss based company UsedSoft innovated the resale of business software and this feature of proprietary software licenses means that certain rights regarding the software are reserved by the software publisher. Therefore, it is typical of EULAs to include terms which define the uses of the software, the most significant effect of this form of licensing is that, if ownership of the software remains with the software publisher, then the end-user must accept the software license. In other words, without acceptance of the license, the end-user may not use the software at all, one example of such a proprietary software license is the license for Microsoft Windows. The most common licensing models are per single user or per user in the appropriate volume discount level, Licensing per concurrent/floating user also occurs, where all users in a network have access to the program, but only a specific number at the same time. Another license model is licensing per dongle which allows the owner of the dongle to use the program on any computer, Licensing per server, CPU or points, regardless the number of users, is common practice as well as site or company licenses
16.
Microsoft Windows
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Microsoft Windows is a metafamily of graphical operating systems developed, marketed, and sold by Microsoft. It consists of families of operating systems, each of which cater to a certain sector of the computing industry with the OS typically associated with IBM PC compatible architecture. Active Windows families include Windows NT, Windows Embedded and Windows Phone, defunct Windows families include Windows 9x, Windows 10 Mobile is an active product, unrelated to the defunct family Windows Mobile. Microsoft introduced an operating environment named Windows on November 20,1985, Microsoft Windows came to dominate the worlds personal computer market with over 90% market share, overtaking Mac OS, which had been introduced in 1984. Apple came to see Windows as an encroachment on their innovation in GUI development as implemented on products such as the Lisa. On PCs, Windows is still the most popular operating system, however, in 2014, Microsoft admitted losing the majority of the overall operating system market to Android, because of the massive growth in sales of Android smartphones. In 2014, the number of Windows devices sold was less than 25% that of Android devices sold and this comparison however may not be fully relevant, as the two operating systems traditionally target different platforms. As of September 2016, the most recent version of Windows for PCs, tablets, smartphones, the most recent versions for server computers is Windows Server 2016. A specialized version of Windows runs on the Xbox One game console, Microsoft, the developer of Windows, has registered several trademarks each of which denote a family of Windows operating systems that target a specific sector of the computing industry. It now consists of three operating system subfamilies that are released almost at the time and share the same kernel. Windows, The operating system for personal computers, tablets. The latest version is Windows 10, the main competitor of this family is macOS by Apple Inc. for personal computers and Android for mobile devices. Windows Server, The operating system for server computers, the latest version is Windows Server 2016. Unlike its clients sibling, it has adopted a strong naming scheme, the main competitor of this family is Linux. Windows PE, A lightweight version of its Windows sibling meant to operate as an operating system, used for installing Windows on bare-metal computers. The latest version is Windows PE10.0.10586.0, Windows Embedded, Initially, Microsoft developed Windows CE as a general-purpose operating system for every device that was too resource-limited to be called a full-fledged computer. The following Windows families are no longer being developed, Windows 9x, Microsoft now caters to the consumers market with Windows NT. Windows Mobile, The predecessor to Windows Phone, it was a mobile operating system
17.
Operating system
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An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. All computer programs, excluding firmware, require a system to function. Operating systems are found on many devices that contain a computer – from cellular phones, the dominant desktop operating system is Microsoft Windows with a market share of around 83. 3%. MacOS by Apple Inc. is in place, and the varieties of Linux is in third position. Linux distributions are dominant in the server and supercomputing sectors, other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can run one program at a time. Multi-tasking may be characterized in preemptive and co-operative types, in preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, e. g. Solaris, Linux, cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking, 32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem, a distributed operating system manages a group of distinct computers and makes them appear to be a single computer. The development of networked computers that could be linked and communicate with each other gave rise to distributed computing, distributed computations are carried out on more than one machine. When computers in a work in cooperation, they form a distributed system. The technique is used both in virtualization and cloud computing management, and is common in large server warehouses, embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy and they are able to operate with a limited number of resources. They are very compact and extremely efficient by design, Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is a system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could run different programs in succession to speed up processing
18.
Personal computer
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A personal computer is a multi-purpose electronic computer whose size, capabilities, and price make it feasible for individual use. PCs are intended to be operated directly by a end-user, rather than by an expert or technician. In the 2010s, PCs are typically connected to the Internet, allowing access to the World Wide Web, personal computers may be connected to a local area network, either by a cable or a wireless connection. In the 2010s, a PC may be, a multi-component desktop computer, designed for use in a location a laptop computer, designed for easy portability or a tablet computer. In the 2010s, PCs run using a system, such as Microsoft Windows, Linux. The very earliest microcomputers, equipped with a front panel, required hand-loading of a program to load programs from external storage. Before long, automatic booting from permanent read-only memory became universal, in the 2010s, users have access to a wide range of commercial software, free software and free and open-source software, which are provided in ready-to-run or ready-to-compile form. Since the early 1990s, Microsoft operating systems and Intel hardware have dominated much of the computer market, first with MS-DOS. Alternatives to Microsofts Windows operating systems occupy a minority share of the industry and these include Apples OS X and free open-source Unix-like operating systems such as Linux and Berkeley Software Distribution. Advanced Micro Devices provides the alternative to Intels processors. PC is an initialism for personal computer, some PCs, including the OLPC XOs, are equipped with x86 or x64 processors but not designed to run Microsoft Windows. PC is used in contrast with Mac, an Apple Macintosh computer and this sense of the word is used in the Get a Mac advertisement campaign that ran between 2006 and 2009, as well as its rival, Im a PC campaign, that appeared in 2008. Since Apples transition to Intel processors starting 2005, all Macintosh computers are now PCs, the “brain” may one day come down to our level and help with our income-tax and book-keeping calculations. But this is speculation and there is no sign of it so far, in the history of computing there were many examples of computers designed to be used by one person, as opposed to terminals connected to mainframe computers. Using the narrow definition of operated by one person, the first personal computer was the ENIAC which became operational in 1946 and it did not meet further definitions of affordable or easy to use. An example of an early single-user computer was the LGP-30, created in 1956 by Stan Frankel and used for science and it came with a retail price of $47, 000—equivalent to about $414,000 today. Introduced at the 1965 New York Worlds Fair, the Programma 101 was a programmable calculator described in advertisements as a desktop computer. It was manufactured by the Italian company Olivetti and invented by the Italian engineer Pier Giorgio Perotto, the Soviet MIR series of computers was developed from 1965 to 1969 in a group headed by Victor Glushkov
19.
IBM PC compatible
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IBM PC compatible computers are those similar to the original IBM PC, XT, and AT, able to run the same software and support the same expansion cards as those. Such computers used to be referred to as PC clones, or IBM clones, Columbia Data Products built the first clone of the IBM personal computer by a clean room implementation of its BIOS. Early IBM PC compatibles used the computer bus as the original PC. The IBM AT compatible bus was named the Industry Standard Architecture bus by manufacturers of compatible computers. The term IBM PC compatible is now a historical description only, only the Apple Macintosh classic Mac OS and macOS kept significant market share without compatibility with the IBM personal computer, so consumers are typically identified as being a PC or Mac user. IBM decided in 1980 to market a low-cost single-user computer as quickly as possible in response to Apple Computers success in the microcomputer market. On 12 August 1981, the first IBM PC went on sale, there were three operating systems available for it. The least expensive and most popular was PC DOS made by Microsoft, in a crucial concession, IBMs agreement allowed Microsoft to sell its own version, MS-DOS, for non-IBM computers. The only component of the original PC architecture exclusive to IBM was the BIOS and this software would run on any machine using MS-DOS or PC-DOS. Software that directly addressed the hardware instead of making standard calls was faster, however, software addressing IBM PC hardware in this way would not run on MS-DOS machines with different hardware. The 808x computer marketplace rapidly excluded all machines which were not hardware-, the 640 KB barrier on conventional system memory available to MS-DOS is a legacy of that period, other non-clone machines, while subject to a limit, could exceed 640 kB. Rumors of lookalike, compatible computers, created without IBMs approval, by June 1983 PC Magazine defined PC clone as a computer accommodate the user who takes a disk home from an IBM PC, walks across the room, and plugs it into the foreign machine. Because of a shortage of IBM PCs that year, many customers purchased clones instead, Columbia Data Products produced the first computer more or less compatible to the IBM PC standard during June 1982, soon followed by Eagle Computer. Compaq announced its first IBM PC compatible in November 1982, the Compaq Portable, the Compaq was the first sewing machine-sized portable computer that was essentially 100% PC-compatible. The company could not copy the BIOS directly as a result of the decision in Apple v. Franklin. Each computer would have its own Original Equipment Manufacturer version of MS-DOS, any software written for MS-DOS would operate on any MS-DOS computer, despite variations in hardware design. This expectation seemed reasonable in the marketplace of the time. Until then Microsoft was based primarily on computer languages such as BASIC, the established small system operating software was CP/M from Digital Research which was in use both at the hobbyist level and by the more professional of those using microcomputers
20.
Graphical user interface
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GUIs were introduced in reaction to the perceived steep learning curve of command-line interfaces, which require commands to be typed on a computer keyboard. The actions in a GUI are usually performed through direct manipulation of the graphical elements, beyond computers, GUIs are used in many handheld mobile devices such as MP3 players, portable media players, gaming devices, smartphones and smaller household, office and industrial controls. Designing the visual composition and temporal behavior of a GUI is an important part of application programming in the area of human–computer interaction. Its goal is to enhance the efficiency and ease of use for the logical design of a stored program. Methods of user-centered design are used to ensure that the language introduced in the design is well-tailored to the tasks. The visible graphical interface features of an application are sometimes referred to as chrome or GUI, typically, users interact with information by manipulating visual widgets that allow for interactions appropriate to the kind of data they hold. The widgets of an interface are selected to support the actions necessary to achieve the goals of users. A model–view–controller allows a structure in which the interface is independent from and indirectly linked to application functions. This allows users to select or design a different skin at will, good user interface design relates to users more, and to system architecture less. Large widgets, such as windows, usually provide a frame or container for the main presentation content such as a web page, smaller ones usually act as a user-input tool. A GUI may be designed for the requirements of a market as application-specific graphical user interfaces. By the 1990s, cell phones and handheld game systems also employed application specific touchscreen GUIs, newer automobiles use GUIs in their navigation systems and multimedia centers, or navigation multimedia center combinations. Sample graphical desktop environments A GUI uses a combination of technologies and devices to provide a platform that users can interact with, a series of elements conforming a visual language have evolved to represent information stored in computers. This makes it easier for people with few computer skills to work with, the most common combination of such elements in GUIs is the windows, icons, menus, pointer paradigm, especially in personal computers. The WIMP style of interaction uses a virtual device to represent the position of a pointing device, most often a mouse. Available commands are compiled together in menus, and actions are performed making gestures with the pointing device, a window manager facilitates the interactions between windows, applications, and the windowing system. The windowing system handles hardware devices such as pointing devices, graphics hardware, window managers and other software combine to simulate the desktop environment with varying degrees of realism. Smaller mobile devices such as personal assistants and smartphones typically use the WIMP elements with different unifying metaphors, due to constraints in space
21.
IBM PC DOS
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IBM PC DOS is a discontinued operating system for the IBM Personal Computer, manufactured and sold by IBM from the 1981 into the 2000s. Before version 6.1, PC DOS was an IBM-branded version of MS-DOS, from version 6.1 on, PC DOS became IBMs independent product. The IBM task force assembled to develop the PC decided that critical components of the machine, including the operating system and this radical break from company tradition of in-house development was one of the key decisions that made the IBM PC an industry standard. At that time private company Microsoft, founded five years before by Bill Gates, was selected for the operating system. IBM wanted Microsoft to retain ownership of whatever software it developed, according to task force member Jack Sams, The reasons were internal. We had a problem being sued by people claiming we had stolen their stuff. It could be expensive for us to have our programmers look at code that belonged to someone else because they would then come back and say we stole it. We had lost a series of suits on this, and so we didnt want to have a product which was clearly someone elses product worked on by IBM people and we went to Microsoft on the proposition that we wanted this to be their product. IBM first contacted Microsoft to look the company over in July 1980, negotiations continued over the next months, and the paperwork was officially signed in early November. Although IBM expected that most customers would use PC DOS, The IBM PC also supported CP/M-86, which became available six months after PC DOS, and UCSD p-System operating systems. IBMs expectation proved correct, one found that 96. 3% of PCs were ordered with the $40 PC-DOS compared to 3. 4% for the $240 CP/M-86. Microsoft first licensed, then purchased 86-DOS from Seattle Computer Products, ORear got 86-DOS to run on the prototype PC in February 1981. 86-DOS had to be converted from 8-inch to 5. 25-inch floppy disks and integrated with the BIOS, IBM had more people writing requirements for the computer than Microsoft had writing code. ORear often felt overwhelmed by the number of people he had to deal with at the ESD facility in Boca Raton, 86-DOS was rebranded IBM PC DOS1.0 for its August 1981 release with the IBM PC. The initial version of DOS was largely based on CP/M-801. x and most of its architecture, function calls, the most significant difference was the fact that it introduced a different file system, FAT12. Unlike all later DOS versions, the DATE and TIME commands were separate rather than part of COMMAND. COM. Single-sided 160 kilobyte 5.25 floppies were the only disk format supported, in late 1981 Paterson, now at Microsoft, began writing PC DOS1.10. It debuted in May 1982 along with the Revision B IBM PC, support for the new double-sided drives was added, allowing 320 kB per disk
22.
Intel 8086
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The 8086 is a 16-bit microprocessor chip designed by Intel between early 1976 and mid-1978, when it was released. The 8086 gave rise to the x86 architecture which eventually became Intels most successful line of processors, in 1972, Intel launched the 8008, the first 8-bit microprocessor. It implemented a set designed by Datapoint corporation with programmable CRT terminals in mind. The device needed several additional ICs to produce a computer, in part due to it being packaged in a small 18-pin memory package. Two years later, Intel launched the 8080, employing the new 40-pin DIL packages originally developed for calculator ICs to enable a separate address bus and it had an extended instruction set that was source compatible with the 8008 and also included some 16-bit instructions to make programming easier. Other well known 8-bit microprocessors that emerged during these years were Motorola 6800, General Instrument PIC16X, MOS Technology 6502, Zilog Z80, the 8086 project started in May 1976 and was originally intended as a temporary substitute for the ambitious and delayed iAPX432 project. It was an attempt to draw attention from the less-delayed 16- and 32-bit processors of other manufacturers and at the time to counter the threat from the Zilog Z80. The programming model and instruction set was based on the 8080 in order to make this possible, however, the 8086 design was expanded to support full 16-bit processing, instead of the fairly basic 16-bit capabilities of the 8080/8085. Instructions directly supporting nested ALGOL-family languages such as Pascal and PL/M were also added, according to principal architect Stephen P. Morse, this was a result of a more software centric approach than in the design of earlier Intel processors. Other enhancements included microcoded multiply and divide instructions and a bus structure better adapted to future coprocessors, the 8086 took a little more than two years from idea to working product, which was considered rather fast for a complex design in 1976–1978. The 8086 was sequenced using a mixture of random logic and microcode and was implemented using depletion-load nMOS circuitry with approximately 20,000 active transistors and it was soon moved to a new refined nMOS manufacturing process called HMOS that Intel originally developed for manufacturing of fast static RAM products. This was followed by HMOS-II, HMOS-III versions, and, eventually, the original chip measured 33 mm² and minimum feature size was 3.2 μm. The architecture was defined by Stephen P. Morse with some help, logic designer Jim McKevitt and John Bayliss were the lead engineers of the hardware-level development team and Bill Pohlman the manager for the project. All internal registers, as well as internal and external buses, are 16 bits wide. A 20-bit external address bus provides a 1 MB physical address space and this address space is addressed by means of internal memory segmentation. The data bus is multiplexed with the bus in order to fit all of the control lines into a standard 40-pin dual in-line package. It provides a 16-bit I/O address bus, supporting 64 KB of separate I/O space, the maximum linear address space is limited to 64 KB, simply because internal address/index registers are only 16 bits wide. Programming over 64 KB memory boundaries involves adjusting the segment registers, some of the control pins, which carry essential signals for all external operations, have more than one function depending upon whether the device is operated in min or max mode
23.
Floppy disk
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Floppy disks are read and written by a floppy disk drive. Floppy disks, initially as 8-inch media and later in 5¼-inch and 3½-inch sizes, were a form of data storage and exchange from the mid-1970s into the mid-2000s. These formats are usually handled by older equipment and these disks and associated drives were produced and improved upon by IBM and other companies such as Memorex, Shugart Associates, and Burroughs Corporation. The term floppy disk appeared in print as early as 1970, in 1976, Shugart Associates introduced the first 5¼-inch FDD. By 1978 there were more than 10 manufacturers producing such FDDs, there were competing floppy disk formats, with hard- and soft-sector versions and encoding schemes such as FM, MFM and GCR. The 5¼-inch format displaced the 8-inch one for most applications, the most common capacity of the 5¼-inch format in DOS-based PCs was 360 kB and in 1984 IBM introduced the 1.2 MB dual-sided floppy disk along with its PC-AT model. IBM started using the 720 kB double-density 3½-inch microfloppy disk on its Convertible laptop computer in 1986 and these disk drives could be added to older PC models. In 1988 IBM introduced a drive for 2.88 MB DSED diskettes in its top-of-the-line PS/2 models, throughout the early 1980s, limitations of the 5¼-inch format became clear. Originally designed to be practical than the 8-inch format, it was itself too large, as the quality of recording media grew. A number of solutions were developed, with drives at 2-, 2½-, 3-, 3½-, the large market share of the 5¼-inch format made it difficult for these new formats to gain significant market share. A variant on the Sony design, introduced in 1982 by a number of manufacturers, was then rapidly adopted. By the end of the 1980s, 5¼-inch disks had been superseded by 3½-inch disks, by the mid-1990s, 5¼-inch drives had virtually disappeared, as the 3½-inch disk became the predominant floppy disk. Floppy disks became ubiquitous during the 1980s and 1990s in their use with computers to distribute software, transfer data. Before hard disks became affordable to the population, floppy disks were often used to store a computers operating system. Most home computers from that period have a primary OS and BASIC stored as ROM, by the early 1990s, the increasing software size meant large packages like Windows or Adobe Photoshop required a dozen disks or more. In 1996, there were a five billion standard floppy disks in use. Then, distribution of packages was gradually replaced by CD-ROMs, DVDs. External USB-based floppy disk drives are available, many modern systems provide firmware support for booting from such drives
24.
86-DOS
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86-DOS is a discontinued operating system developed and marketed by Seattle Computer Products for its Intel 8086-based computer kit. Initially known as QDOS the name was changed to 86-DOS once SCP started licensing the operating system in 1980, 86-DOS had a command structure and application programming interface that imitated that of Digital Researchs CP/M operating system, which made it easy to port programs from the latter. The system was purchased by Microsoft and developed further as MS-DOS, 86-DOS was created because sales of the Seattle Computer Products 8086 computer kit, demonstrated in June 1979 and shipped in November, were languishing due to the absence of an operating system. The only software which SCP could sell with the board was Microsofts Standalone Disk BASIC-86, SCP wanted to offer the 8086-version of CP/M that Digital Research had announced, but its release date was uncertain. This was not the first time Digital Research had lagged behind hardware developments, in April 1980 SCP assigned 24-year-old Tim Paterson to develop a substitute for CP/M-86. At the same time he made a number of changes and enhancements to address what he saw as CP/Ms shortcomings. CP/M cached file system information in memory for speed, but this required a user to force an update to a disk before removing it, if the user forgot, Paterson took the safer but slower approach of updating the disk with each operation. CP/Ms PIP command, which copied files, supported several special file names that referred to hardware such as printers. Paterson built these names into the system as device files so that any program could use them. He gave his copying program the more intuitive name COPY, rather than implementing CP/Ms file system, he drew on Microsoft Standalone Disk BASIC-86s FAT filesystem. By mid-1980 SCP advertised 86-DOS, priced at $95 for owners of its $12908086 board, in October 1980, IBM was developing what would become the original IBM Personal Computer. CP/M was by far the most popular operating system in use at the time, IBMs representatives visited Digital Research and discussed licensing with Digital Researchs licensing representative, Dorothy Kildall, who hesitated to sign IBMs non-disclosure agreement. Although the NDA was later accepted, Digital Research would not accept IBMs proposal of $250,000 in exchange for as many copies as IBM could sell, insisting on the usual royalty-based plan. In later discussions between IBM and Bill Gates, Gates mentioned the existence of 86-DOS and IBM representative Jack Sams told him to get a license for it, Microsoft purchased a non-exclusive license for 86-DOS from Seattle Computer Products in December 1980 for $25,000. In May 1981, it hired Tim Paterson to port the system to the IBM PC, IBM watched the developments daily, submitted over 300 change requests before it accepted the product and wrote the user manual for it. In July 1981, a month before the PCs release, Microsoft purchased all rights to 86-DOS from SCP for $50,000, Microsoft licensed 86-DOS to IBM, and it became PC DOS1.0. This license also permitted Microsoft to sell DOS to other companies, the deal was spectacularly successful, and SCP later claimed in court that Microsoft had concealed its relationship with IBM in order to purchase the operating system cheaply. SCP ultimately received a 1 million dollar settlement payment, when Digital Research founder Gary Kildall examined PC DOS and found that it duplicated CP/Ms programming interface, he wanted to sue IBM, which at the time claimed that PC DOS was its own product
25.
Seattle Computer Products
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Seattle Computer Products was a Seattle, Washington microcomputer hardware company which was one of the first manufacturers of computer systems based on the 16-bit Intel 8086 processor. SCP shipped an operating system for that hardware about a year before the release of the PC, SCP was staffed partly by high-school students from nearby communities who soldered and assembled the computers. Some of them would work for Microsoft. Twenty-two-year-old Tim Paterson was hired in June 1978 by SCPs owner Rod Brock, Paterson had a prototype working by May 1979, and he took his computer over to Microsoft, who were working on an 8086 BASIC, which was working before the end of May. When the board began shipping in November, standalone Microsoft BASIC was offered as an option, digital Research, whose 8-bit CP/M operating system was the industry standard, was working on an 8086-compatible version called CP/M-86, but the delay in its release was costing SCP sales. In order to fill this void, Paterson wrote QDOS over a period starting in April 1980. QDOS0.11 was finished in August 1980, and SCP began shipping it in September 1980, the operating system was renamed to 86-DOS in December 1980. Realizing that Microsoft was making significant profit on the 86-DOS operating system, thanks to the deal with Microsoft, additional capital allowed Seattle Computer to expand its memory business into providing additional memory for PC products. The company had its best year in 1982, reaping more than a million dollars in profit on about $4 million in sales, by 1985, however, SCPs business was having difficulty trying to compete with offshore products, and Brock decided to sell the company. The only major asset SCP had left was the license it received from Microsoft when it signed over rights to 86-DOS. Brock planned to sell the license to the highest bidder, with a such as the Tandy Corporation in mind. After Microsoft objected to Brocks exaggerated interpretation of the agreement and informed Brock that his license was nontransferable, the ensuing lawsuit was highly technical and grew to fill hundreds of pages in the months leading up to trial. The trial began at the end of 1986 and lasted three weeks, an out-of-court settlement was reached while the jury was deliberating. Microsoft paid SCP $925,000 and reclaimed its license for DOS SCP went out of business in the late 80s as the market for Intel 8086 systems became dominated by PC compatible computers
26.
Digital Research
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Digital Research, Inc. was the company created by Dr. Gary Kildall to market and develop his CP/M operating system and related products. It was the first large company in the microcomputer world. Digital Research was based in Pacific Grove, California, the companys operating systems, starting with CP/M for 8080/Z80-based microcomputers, were the de facto standard of their era, as MS-DOS and Microsoft Windows came later. DRs product suite included the original CP/M and its various offshoots, DR-DOS which was a MS-DOS compatible version of CP/M, and MP/M, the first 16-bit system was CP/M-86, which was to be unsuccessful in competition with MS-DOS. There followed Concurrent CP/M, a version of the multi-tasking MP/M-86 featuring virtual consoles from which applications could be launched to run concurrently. Successive revisions of this system, which gradually supported MS-DOS applications, in May 1983 Digital Research announced that it would offer PC DOS versions of all of its languages and utilities. It remained influential, with $45 million in 1983 sales making Digital Research the fourth-largest microcomputer software company, jerry Pournelle warned later that year, however, that Many people of stature seem to have left or are leaving Digital Research. DR had better get its act together, in 1985, soon after the introduction of the Intel 80286, Digital Research introduced a real-time system, initially called Concurrent DOS286 and subsequently FlexOS. This exploited the greater memory addressing capability of the new CPU to provide a more flexible multi-tasking environment, there was a small but powerful set of system APIs, each with a synchronous and an asynchronous variant. Pipes were supported, and all named resources could be aliased by setting Environment variables and this system was to enjoy enduring favour in point-of-sale systems and was adopted as the basis for IBM4680 OS and IBM4690 OS. Digital Research was purchased by Novell in 1991, primarily for Novell to gain access to the operating system line. Digital Research produced a selection of programming language compilers and interpreters for their OS-supported platforms, including C, Pascal, COBOL, Forth, PL/I, PL/M, CBASIC, BASIC, and Logo. They also produced a version of the GKS graphics standard called GSX. Less known are their application programs, limited largely to the GSX-based DR DRAW, Dr. Halo for DOS, at the time IBM Personal Computer was being developed, Digital Researchs CP/M was the dominant operating system of the day. IBM asked DR to supply a version of CP/M written for the Intel 8086 microprocessor as the operating system for the PC. Digital Research, uneasy about making such an agreement with IBM, Microsoft seized this opportunity to supply an OS, in addition to other software for the new IBM PC. When the IBM PC arrived in late 1981, it came with PC DOS, which was developed from 86-DOS, by mid-1982, it was marketed as MS-DOS for use in hardware-compatible non-IBM computers. This one decision resulted in Microsoft becoming the name in computer software
27.
CP/M
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Initially confined to single-tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations and were migrated to 16-bit processors. The combination of CP/M and S-100 bus computers was loosely patterned on the MITS Altair and this computer platform was widely used in business through the late 1970s and into the mid-1980s. CP/M increased the size for both hardware and software by greatly reducing the amount of programming required to install an application on a new manufacturers computer. An important driver of innovation was the advent of low-cost microcomputers running CP/M, as independent programmers and hackers bought them. CP/M was displaced by MS-DOS soon after the 1981 introduction of the IBM PC, manufacturers of CP/M-compatible systems customized portions of the operating system for their own combination of installed memory, disk drives, and console devices. CP/M would also run on based on the Zilog Z80 processor since the Z80 was compatible with 8080 code. CP/M used the 7-bit ASCII set, the other 128 characters made possible by the 8-bit byte were not standardized. For example, one Kaypro used them for Greek characters, WordStar used the 8th bit as an end-of-word marker. The BIOS and BDOS were memory-resident, while the CCP was memory-resident unless overwritten by an application, a number of transient commands for standard utilities were also provided. The transient commands resided in files with the extension. COM on disk, the BIOS directly controlled hardware components other than the CPU and main memory. It contained functions such as input and output and the reading and writing of disk sectors. The BDOS implemented the CP/M file system and some input/output abstractions on top of the BIOS, the CCP took user commands and either executed them directly or loaded and started an executable file of the given name. Third-party applications for CP/M were also essentially transient commands, the BDOS, CCP and standard transient commands were the same in all installations of a particular revision of CP/M, but the BIOS portion was always adapted to the particular hardware. Adding memory to a computer, for example, meant that the CP/M system had to be reinstalled with an updated BIOS capable of addressing the additional memory, a utility was provided to patch the supplied BIOS, BDOS and CCP to allow them to be run from higher memory. Once installed, the system was stored in reserved areas at the beginning of any disk which would be used to boot the system. On start-up, the bootloader would load the system from the disk in drive A. By modern standards CP/M was primitive, owing to the constraints on program size. With version 1.0 there was no provision for detecting a changed disk, if a user changed disks without manually rereading the disk directory the system would write on the new disk using the old disks directory information, ruining the data stored on the disk
28.
IBM Personal Computer
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The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12,1981 and it was created by a team of engineers and designers under the direction of Don Estridge of the IBM Entry Systems Division in Boca Raton, Florida. IBM compatible became an important criterion for sales growth, only the Apple Macintosh family kept significant market share without compatibility with the IBM personal computer, International Business Machines, one of the worlds largest companies, had a 62% share of the mainframe computer market in 1981. Its share of the computer market, however, had declined from 60% in 1970 to 32% in 1980. In 1979 BusinessWeek asked, Is IBM just another stodgy, mature company, by 1981 its stock price had declined by 22%. IBMs earnings for the first half the year grew by 5. 3%—one third of the inflation rate—while those of minicomputer maker Digital Equipment Corporation grew by more than 35%. B. M, No longer dominates the computer business. IBM wished to avoid the outcome with the new personal computer industry, dominated by the Commodore PET, Atari 8-bit family, Apple II, Tandy Corporations TRS-80. With $150 million in sales by 1979 and projected growth of more than 40% in the early 1980s. The Japanese project, codenamed Go, ended before the 1981 release of the American-designed IBM PC codenamed Chess, whether IBM had waited too long to enter an industry in which Apple and others were already successful was unclear. An observer stated that IBM bringing out a computer would be like teaching an elephant to tap dance. Successful microcomputer company Vector Graphics fiscal 1980 revenue was $12 million, the company only sold through its internal sales force, had no experience with resellers or retail stores, and did not introduce the first product designed to work with non-IBM equipment until 1980. Another observer claimed that IBM made decisions so slowly that, when tested, as with other large computer companies, its new products typically required about four to five years for development. IBM had to learn how to develop, mass-produce. The potential importance to microcomputers of a company so prestigious, that a saying in American companies stated No one ever got fired for buying IBM, was nonetheless clear. InfoWorld, which described itself as The Newsweekly for Microcomputer Users, stated that for my grandmother, is far and away the media star, not because of its features, but because it exists at all. When the number eight company in the Fortune 500 enters the field, the influence of a personal computer made by a company whose name has literally come to mean computer to most of the world is hard to contemplate. The editorial acknowledged that some factions in our industry have looked upon IBM as the enemy, desktop sized programmable calculators by Hewlett Packard had evolved into the HP9830 BASIC language computer by 1972. In 1972–1973 a team led by Dr. SCAMP emulated an IBM1130 minicomputer to run APL\1130, in 1973 APL was generally available only on mainframe computers, and most desktop sized microcomputers such as the Wang 2200 or HP9800 offered only BASIC
29.
Multi-user
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Multi-user software is software that allows access by multiple users of a computer. Most batch processing systems for mainframe computers may also be considered multi-user, however, the term multitasking is more common in this context. An example is a Unix server where multiple remote users have access to the Unix shell prompt at the same time, another example uses multiple X Window sessions spread across multiple terminals powered by a single machine - this is an example of the use of thin client. Similar functions were available under MP/M, Concurrent DOS, Multiuser DOS and FlexOS. The operating system provides isolation of each users processes from other users, management systems are implicitly designed to be used by multiple users, typically one system administrator or more and an end-user community. Multi-user operating systems such as Unix sometimes have a user mode or runlevel available for emergency maintenance. Multiseat Interix in a Multi-User Windows TSE Environment paper about the Unix multi-user model and MS-Windows NT TSE
30.
Unix
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Among these is Apples macOS, which is the Unix version with the largest installed base as of 2014. Many Unix-like operating systems have arisen over the years, of which Linux is the most popular, Unix was originally meant to be a convenient platform for programmers developing software to be run on it and on other systems, rather than for non-programmer users. The system grew larger as the system started spreading in academic circles, as users added their own tools to the system. Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration and these concepts are collectively known as the Unix philosophy. By the early 1980s users began seeing Unix as a universal operating system. Under Unix, the system consists of many utilities along with the master control program. To mediate such access, the kernel has special rights, reflected in the division between user space and kernel space, the microkernel concept was introduced in an effort to reverse the trend towards larger kernels and return to a system in which most tasks were completed by smaller utilities. In an era when a standard computer consisted of a disk for storage and a data terminal for input and output. However, modern systems include networking and other new devices, as graphical user interfaces developed, the file model proved inadequate to the task of handling asynchronous events such as those generated by a mouse. In the 1980s, non-blocking I/O and the set of inter-process communication mechanisms were augmented with Unix domain sockets, shared memory, message queues, and semaphores. In microkernel implementations, functions such as network protocols could be moved out of the kernel, Multics introduced many innovations, but had many problems. Frustrated by the size and complexity of Multics but not by the aims and their last researchers to leave Multics, Ken Thompson, Dennis Ritchie, M. D. McIlroy, and J. F. Ossanna, decided to redo the work on a much smaller scale. The name Unics, a pun on Multics, was suggested for the project in 1970. Peter H. Salus credits Peter Neumann with the pun, while Brian Kernighan claims the coining for himself, in 1972, Unix was rewritten in the C programming language. Bell Labs produced several versions of Unix that are referred to as Research Unix. In 1975, the first source license for UNIX was sold to faculty at the University of Illinois Department of Computer Science, UIUC graduate student Greg Chesson was instrumental in negotiating the terms of this license. During the late 1970s and early 1980s, the influence of Unix in academic circles led to adoption of Unix by commercial startups, including Sequent, HP-UX, Solaris, AIX. In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4, in the 1990s, Unix-like systems grew in popularity as Linux and BSD distributions were developed through collaboration by a worldwide network of programmers
31.
Xenix
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Xenix is a discontinued version of the Unix operating system for various microcomputer platforms, licensed by Microsoft from AT&T Corporation in the late 1970s. The Santa Cruz Operation later acquired rights to the software. In the mid-to-late 1980s, Xenix was the most common Unix variant, Microsoft chairman Bill Gates said in 1996 that for a long time that company had the highest-volume AT&T Unix license. Bell Labs, the developer of Unix, was part of the regulated Bell System and it instead licensed the software to others. Because Microsoft was not able to license the UNIX name itself, Microsoft called Xenix a universal operating environment. The first version of Xenix was very close to the original UNIX version 7 source on the PDP-11, Microsoft said in 1981, and later versions were to incorporate its own fixes and improvements. The first port was for the Z8001 16-bit processor, the first customer ship was January 1981 for Central Data Corporation of Illinois, the first 8086 port was for the Altos Computer Systems non-PC-compatible 8600-series computers. Intel sold complete computers with Xenix under their Intel System 86 brand and this included processor boards like iSBC 86/12 and also MMU boards such as the iSBC309. The first Intel Xenix systems shipped in July 1982, seattle Computer Products also made 8086 computers bundled with Xenix, like their Gazelle II, which used the S-100 bus and was available in late 1983 or early 1984. There was also a port for IBM System 9000, SCO had initially worked on its own PDP-11 port of V7, called Dynix, but then struck an agreement with Microsoft for joint development and technology exchange on Xenix in 1982. In 1984, a port to the 68000-based Apple Lisa was jointly developed by SCO and Microsoft, the difficulty in porting to the various 8086 and Z8000-based machines, said Microsoft in its 1983 OEM directory, had been the lack of a standardized memory management unit and protection facilities. A generally available port to the unmapped Intel 8086/8088 architecture was done by The Santa Cruz Operation around 1983, SCO Xenix for the PC XT shipped sometime in 1984 and contained some enhancement from 4. 2BSD, it also supported the Micnet local area networking. The later 286 version of Xenix leveraged the integrated MMU present on this chip, the 286 Xenix was accompanied by new hardware from Xenix OEMs. For example, the Sperry PC/IT, an IBM PC AT clone, was advertised as capable of supporting eight simultaneous dumb terminal users under this version and it was followed by a System V.2 codebase in Xenix 5.0. Microsoft hopes that XENIX will become the choice for software production and exchange. Microsoft referred to its own MS-DOS as its single-user, single-tasking operating system, microsofts Chris Larson described MS-DOS2. 0s Xenix compatibility as the second most important feature. AT&T started selling System V, however, after the breakup of the Bell System, Microsoft, believing that it could not compete with Unixs developer, decided to abandon Xenix. The decision was not immediately transparent, which led to the term vaporware and it agreed with IBM to develop OS/2, and the Xenix team was assigned to that project
32.
Motorola 68000
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The Motorola 68000 is a 32-bit CISC microprocessor with a 16-bit external data bus, designed and marketed by Motorola Semiconductor Products Sector. After 38 years in production, the 68000 architecture is still in use, the 68000 grew out of the MACSS project, begun in 1976 to develop an entirely new architecture without backward compatibility. It would be a higher-power sibling complementing the existing 8-bit 6800 line rather than a compatible successor, in the end, the 68000 did retain a bus protocol compatibility mode for existing 6800 peripheral devices, and a version with an 8-bit data bus was produced. However, the designers focused on the future, or forward compatibility. For instance, the CPU registers are 32 bits wide, though few self-contained structures in the processor itself operate on 32 bits at a time. The MACSS team drew heavily on the influence of minicomputer processor design, such as the PDP-11 and VAX systems, in the mid 1970s, the 8-bit microprocessor manufacturers raced to introduce the 16-bit generation. National Semiconductor had been first with its IMP-16 and PACE processors in 1973–1975, Intel had worked on their advanced 16/32-bit Intel iAPX432 since 1975 and their Intel 8086 since 1976. Arriving late to the 16-bit arena afforded the new processor more transistors, 32-bit macroinstructions, the original MC68000 was fabricated using an HMOS process with a 3.5 µm feature size. Formally introduced in September 1979, Initial samples were released in February 1980, Initial speed grades were 4,6, and 8 MHz.10 MHz chips became available during 1981, and 12.5 MHz chips by June 1982. The 16.67 MHz 12F version of the MC68000, the fastest version of the original HMOS chip, was not produced until the late 1980s, tom Gunter, retired Corporate Vice President at Motorola, is known as the Father of the 68000. The 68000 was used in Microsoft Xenix systems as well as an early NetWare Unix-based Server, the 68000 was used in the first generation of desktop laser printers including the original Apple Inc. In 1982, the 68000 received an update to its ISA allowing it to virtual memory and to conform to the Popek. The updated chip was called the 68010, a further extended version which exposed 31 bits of the address bus was also produced, in small quantities, as the 68012. To support lower-cost systems and control applications with smaller sizes, Motorola introduced the 8-bit compatible MC68008. This was a 68000 with an 8-bit data bus and an address bus. After 1982, Motorola devoted more attention to the 68020 and 88000 projects, several other companies were second-source manufacturers of the HMOS68000. These included Hitachi, who shrank the size to 2.7 µm for their 12.5 MHz version, Mostek, Rockwell, Signetics, Thomson/SGS-Thomson. Toshiba was also a maker of the CMOS 68HC000
33.
Zilog Z8000
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The Z8000 is a 16-bit microprocessor introduced by Zilog in 1979. The architecture was designed by Bernard Peuto while the logic and physical implementation was done by Masatoshi Shima, the Z8000 was not Z80-compatible, and although it saw steady use well into the 1990s, it was not very widely used. However, the Z16C01 and Z16C02 Serial Communication Controllers still use the Z8000 core, although fundamentally a 16-bit architecture, some versions had 7-bit segment registers that extended the address space to 8 megabytes. The register set consisted of sixteen 16-bit general purpose registers, labeled R0 through R15 and these can be concatenated into eight 32-bit registers, labeled RR0/RR2/. /RR14, or into four 64-bit registers, labeled RQ0/RQ4/RQ8/RQ12. The first eight registers can be subdivided into sixteen 8-bit registers, labeled RL0 though RL7 for the lower byte, register R15 is designated as stack pointer. On the Z8001, register R14 is used for selecting the stack segment, there was both a user mode and a supervisor mode, selected by bit 14 in the flag register. In supervisor mode, the stack registers point to the system stack, in user mode, the stack registers point to the normal stack and all privileged instructions will generate a fault. Like the Zilog Z80, the Z8000 included built-in DRAM refresh circuitry, although an attractive feature for designers of the time, overall the Z8000 was not especially fast, had some bugs, and in the end it was overshadowed by the Intel x86 family. One notable use of the Z8000 series was by Namco in the design of its famous Pole Position series of racing videogames, two Z8002s were incorporated into the design. Indeed, an active order code and datasheet may still be located upon the Zilog website, the end of life notice was sent in 2012. The Zilog Z80000 was a 32-bit follow-on design, in the early 1980s, the Zilog Z8000 CPU was popular for desktop sized Unix machines. The onchip MMU reduced manufacturing cost by eliminating the need for additional support required to support virtual memory. These low-cost Unix systems allowed small businesses to run a true multi-user system and they usually had only RS232 serial ports and parallel printer ports instead of built in graphics, as was typical for servers of the time. Z8000-based computer systems included Zilogs own System 8000 series, as well as manufacturers, Jan 1980, C8000 from Onyx Systems, early Unix multi-user system. Other Z8000-based computer systems, Olivetti M20, M30, M40, M50, 1987-1989 the East German EAW produced the Workstation/Multiuser System P8000 based on the East German U8000 clone of the Z8000. The Z8000 can be found in rare but well-known computers. Some third parties also manufactured the Z8000 including AMD, SGS-Ates, Toshiba, the Zilog S8000 computer came out with a version of Unix called ZEUS. This version of Unix was not based on Xenix but on Interactives Unix, there may have been a Xenix version from some other company as, in 1979, Xenix was Intel 8088/8086 based
34.
LSI-11
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The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 had several innovative features, and was easier to program than its predecessors through the additional general-purpose registers. The PDP-11 replaced the PDP-8 in many applications, although both product lines lived in parallel for more than 10 years. In total, around 600,000 PDP-11s of all models were sold and its successor in the mid-range minicomputer niche was the 32-bit VAX-11, named as a nod to the PDP-11s popularity. The PDP-11 is considered by experts to be the most popular minicomputer ever. Design features of the PDP-11 influenced the design of most late-1970s computer systems including the Intel x86, design features of PDP-11 operating systems, as well as other operating systems from Digital Equipment, influenced the design of other operating systems such as CP/M and hence also MS-DOS. For a decade, the PDP-11 was the smallest system that could run Unix and it is commonly stated that the C programming language took advantage of several low-level PDP-11–dependent programming features, albeit not originally by design. In 1967–68, DEC engineers designed a 16-bit, word-addressed machine, management cancelled the project and some of the engineers later left DEC and produced it as the Data General Nova. A subsequent effort, code-named Desk Calculator, looked at a variety of options before choosing what became the 16-bit PDP-11, DECs previous PDP-8 and PDP-9 had 12- and 18-bit words, the PDP-11 family was announced in January 1970 and shipments began early that year. DEC sold over 170,000 PDP-11s in the 1970s, initially manufactured of small-scale transistor–transistor logic, a single-board large scale integration version of the processor was developed in 1975. A two-or-three-chip processor, the J-11 was developed in 1979, the last models of the PDP-11 line were the PDP-11/94 and -11/93 introduced in 1990. The PDP-11 processor architecture has an orthogonal instruction set. For example, instead of such as load and store. More complex instructions such as add likewise can have memory, register, input, most operands can apply any of eight addressing modes to eight registers. The addressing modes provide register, immediate, absolute, relative, deferred, and indexed addressing, use of relative addressing lets a machine-language program be position-independent. Early models of the PDP-11 had no dedicated bus for input/output, an input/output device determined the memory addresses to which it would respond, and specified its own interrupt vector and interrupt priority. DEC openly published the basic Unibus specifications, even offering prototyping bus interface circuit boards, the Unibus made the PDP-11 suitable for custom peripherals. Higher-performance members of the PDP-11 family, starting with the PDP-11/45 Unibus and 11/83 Q-bus systems, instead, memory was interfaced by dedicated circuitry and space in the CPU cabinet, while the Unibus continued to be used for I/O only
35.
Byte (magazine)
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Byte magazine was an American microcomputer magazine, influential in the late 1970s and throughout the 1980s because of its wide-ranging editorial coverage. Coverage was in-depth with much detail, rather than user-oriented. Print publication ceased in 1998 and online publication in 2013, Byte started in 1975, shortly after the first personal computers appeared as kits advertised in the back of electronics magazines. Byte was published monthly, with a yearly subscription price of $10. In 1975 Wayne Green was the editor and publisher of 73 and his ex-wife, on May 25th we made a deal with the publisher of a small computer hobby magazine to take over as editor of a new publication which would start in August. Carl Helmers published a series of six articles in 1974 that detailed the design and construction of his Experimenters Computer System, in January 1975 this became the monthly ECS magazine with 400 subscribers. The last issue was published on May 12,1975 and in June the subscribers were mailed a notice announcing Byte magazine, carl wrote to another hobbyist newsletter, Micro-8 Computer User Group Newsletter, and described his new job as editor of Byte magazine. I got a note in the mail about two weeks ago from Wayne Green, publisher of 73 Magazine essentially saying hello and why dont you come up, the net result of a follow up is the decision to create BYTE magazine using the facilities of Green Publishing Inc. I will end up with the focus for the magazine. Virginia Londner Green had returned to 73 in the December 1974 issue, the first five issues of Byte were published by Green Publishing and the name was changed to Byte Publications starting with the February 1976 issue. Carl Helmers was a co-owner of Byte Publications, the first four issues were produced in the offices of 73 and Wayne Green was listed as the publisher. One day in November 1975 Wayne came to work and found that the Byte magazine staff had moved out, the February 1976 issue of Byte has a short story about the move. After a start which reads like a light opera with an episode or two reminiscent of the Keystone Cops, Byte magazine finally has moved into separate offices of its own. Wayne Green was not happy about losing Byte magazine so he was going to start a new one called Kilobyte, Byte quickly trademarked KILOBYTE as a cartoon series in Byte magazine. The new magazine was called Kilobaud, there was competition and animosity between Byte Publications and 73 Inc. but both remained in the small town of Peterborough, New Hampshire. Byte was able to attract advertising and articles from many well-knowns, soon-to-be-well-knowns, articles in the first issue included Which Microprocessor For You. by Hal Chamberlin, Write Your Own Assembler by Dan Fylstra and Serial Interface by Don Lancaster. Advertisements from Godbout, MITS, Processor Technology, SCELBI, and Sphere appear, early articles in Byte were do-it-yourself electronic or software projects to improve small computers. A continuing feature was Ciarcias Circuit Cellar, a column in which electronic engineer Steve Ciarcia described small projects to modify or attach to a computer, Byte ran Microsofts first advertisement, as Micro-Soft, to sell a BASIC interpreter for 8080-based computers
36.
Computer multitasking
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In computing, multitasking is a concept of performing multiple tasks over a certain period of time by executing them concurrently. As a result, a computer executes segments of multiple tasks in a manner, while the tasks share common processing resources such as central processing units. Multitasking does not necessarily mean that multiple tasks are executing at exactly the same time, even on multiprocessor or multicore computers, which have multiple CPUs/cores so more than one task can be executed at once, multitasking allows many more tasks to be run than there are CPUs. In the case of a computer with a single CPU, only one task is said to be running at any point in time, multitasking solves the problem by scheduling which task may be the one running at any given time, and when another waiting task gets a turn. The act of reassigning a CPU from one task to one is called a context switch. Multiprogramming systems are designed to maximize CPU usage, in time-sharing systems, the running task is required to relinquish the CPU, either voluntarily or by an external event such as a hardware interrupt. Time sharing systems are designed to allow programs to execute apparently simultaneously. In real-time systems, some waiting tasks are guaranteed to be given the CPU when an event occurs. Real time systems are designed to control devices such as industrial robots. The term multitasking has become a term, as the same word is used in many other languages such as German, Italian, Dutch, Danish. In the early days of computing, CPU time was expensive, when the computer ran a program that needed access to a peripheral, the central processing unit would have to stop executing program instructions while the peripheral processed the data. The first computer using a system was the British Leo III owned by J. Lyons. During batch processing, several different programs were loaded in the memory. When the first program reached an instruction waiting for a peripheral, the context of program was stored away. The process continued until all programs finished running, multiprogramming doesnt give any guarantee that a program will run in a timely manner. Indeed, the very first program may very well run for hours without needing access to a peripheral. As there were no users waiting at a terminal, this was no problem, users handed in a deck of punched cards to an operator. Multiprogramming greatly reduced wait times when multiple batches were being processed, the expression time sharing usually designated computers shared by interactive users at terminals, such as IBMs TSO, and VM/CMS
37.
Breakup of the Bell System
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This effectively took the monopoly that was the Bell System and split it into entirely separate companies that would continue to provide telephone service. This divestiture was initiated by the filing in 1974 by the United States Department of Justice of an antitrust lawsuit against AT&T, AT&T was, at the time, the sole provider of telephone service throughout most of the United States. Furthermore, most telephonic equipment in the United States was produced by its subsidiary and this vertical integration led AT&T to have almost total control over communication technology in the country, which led to the antitrust case, United States v. AT&T. The plaintiff in the court complaint asked the court to order AT&T to divest ownership of Western Electric, feeling that it was about to lose the suit, AT&T proposed an alternative — the breakup of the biggest corporation in American history. It proposed that it retain control of Western Electric, Yellow Pages, the Bell trademark, Bell Labs and it also proposed that it be freed from a 1956 anti-trust consent decree that barred it from participating in the general sale of computers. In return, it proposed to give up ownership of the operating companies. This last concession, it argued, would achieve the Governments goal of creating competition in supplying telephone equipment and supplies to the operative companies. The settlement was finalized on January 8,1982, with changes ordered by the decree court, the regional holding companies got the Bell trademark, Yellow Pages. This divestiture reduced the value of AT&T by approximately 70%. The breakup of the Bell System resulted in creation of seven independent companies that were formed from the original twenty-two AT&T-controlled members of the System. At the time of the breakup, these companies were, NYNEX, acquired by Bell Atlantic in 1996, now part of Verizon Communications Pacific Telesis, acquired by SBC in 1997, now part of AT&T Inc. Both of these companies were monopolies in their areas, received Western Electric equipment and had agreements with AT&T whereby they were provided with long distance service. The breakup led to a surge of competition in the long distance telecommunications market by companies such as Sprint, one consequence of the breakup was that local residential service rates, which were formerly subsidized by long distance revenues, began to rise faster than the rate of inflation. Long-distance rates, meanwhile, fell due both to the end of this subsidy and increased competition, the FCC established a system of access charges where long distance networks paid the more expensive local networks both to originate and terminate a call. In this way, the subsidies of the Bell System became explicit post-divestiture. These access charges became a source of controversy as one company after another sought to arbitrage the network. In 2002 the FCC declared that Internet service providers would be treated as if they were local and this led to VoIP service providers arguing that they did not have to pay access charges, resulting in significant savings for VoIP calls. However, an FCC order issued in December 2011 declared that all VoIP services would have to pay the charges for nine years, another consequence of the divestiture was in how both national broadcast television and radio networks distributed their programming to their local affiliated stations
38.
AT&T Computer Systems
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AT&T Computer Systems is the generic name for American Telephone & Telegraphs unsuccessful attempt to compete in the computer business. In return for divesting the local Bell Operating Companies, AT&T was allowed to have a division to sell computer hardware and software. After divestiture, January 1,1984, American Telephone & Telegraph was required to put its computer business into a fully separated subsidiary called AT&T Information Systems. Software was developed in New Jersey locations, and software, hardware, in 1991, the AT&T Data Systems Group, with the three divisions was announced to the public. In 1992 the Terminals division was sold to Memorex-Telex, and the Printer division, by the mid-1990s, this left only AT&T Computer Systems. AT&T Computer Systems was the home of the UNIX System V operating system, the important System V Interface Definition was written, attempting to standardize the various flavors of Unix, and define the official interfaces which made up a UNIX operating system. In 1988, AT&T announced its intent to buy up to a 20% stake in Sun Microsystems, upset at their academic-minded supplier now turned competitor, the Gang of Seven founded the Open Software Foundation, each contributing source code from their UNIX SVR3 versions. AT&T founded the UNIX International organization as a counter-response to the OSF, throughout the 1980s and early 1990s, AT&T-CS produced many firsts in the computer world, besides the UNIX operating system itself. The 3B5 and 3B15 were the first computers to be designed with the 32-bit WE32000 microprocessor, the 3B5, 3B15, and 3B20S and 3B20D were aimed at the former AT&T subsidiaries the RBOCs. However, starting with the ATT-IS days, development of a version of this hardware commenced. The product line was started in 1982, with the introduction of the UNIX PC and this product was not a success, in part due to the high margin on the machines, AT&T sold the machine for $8,000 although their cost was approximately $4,000. The next product was the 3B2 product line and it ranged from a 3B2/200 unit, to a 3B2/1000, these machines were sold with System V Release 2, and later System V Release 3. The 3B2 was the platform for SVR3. The 3B2 was the first desktop supermicrocomputer with a 32-bit microprocessor, the model 300 and 400 series were uniprocessors. The 3B2 became the official porting base for UNIX System V Release 3, later versions were the first to introduce UNIX asymmetric multiprocessing and nearly symmetrical multiprocessing. The Falcon won the highly touted US Air Force Office Automation contract, initially estimated at $1.7 billion, because the 3B5/3B15 was a large minicomputer with only 1 CPU, it was sometimes referred to as the body without a brain. Also the small 3B2 had a design with less expansion capability. The Companion was developed, the first laptop computer to have a 32-bit CPU, both were so outrageous and ahead of their time, they were never marketed
