1.
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
2.
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
3.
Novell
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/noʊˈvɛl/ was a software and services company headquartered in Provo, Utah. It had been instrumental in making Utah Valley a focus for technology, Novell technology contributed to the emergence of local area networks, which displaced the dominant mainframe computing model and changed computing worldwide. The company began in 1979 in Orem, Utah as Novell Data Systems Inc. a hardware manufacturer producing CP/M-based systems, former Eyring Research Institute employee Dennis Fairclough was the member of the original team that started Novell Data Systems. It was co-founded by George Canova, Darin Field, and Jack Davis, victor V. Vurpillat brought the deal to Pete Musser, chairman of the board of Safeguard Scientifics, Inc. who provided the seed funding. The company initially did not do well, the microcomputer produced by the company was comparatively weak against performance by competitors. In order to compete on systems sales Novell Data Systems planned a program to more than one microcomputer to operate together. The former ERI employees Drew Major, Dale Neibaur and Kyle Powell, the Safeguard board then ordered Musser to shut Novell down. Davis left Novell Data Systems in November 1981, followed by Canova in March 1982, rubinstein and Dolin, along with Jack Messman, interviewed and hired Raymond Noorda. The required funding was obtained through an offering to Safeguard shareholders, managed by the Cleveland brokerage house, Prescott, Ball and Turben. Major, Neibaur and Powell continued to support Novell through their SuperSet Software Group, in January 1983, the companys name was shortened to Novell, Inc. and Raymond Noorda became the head of the firm. Later that same year, the company introduced its most significant product, a network interface card was developed for the IBM PC industry standard architecture bus. The server was using the first network operating system called ShareNet, later, ShareNet was ported to run on the Intel platform and renamed NetWare. The first commercial release of NetWare was version 1.5, Novell based its network protocol on Xerox Network Systems, and created its own standards from IDP and SPP, which it named Internetwork Packet Exchange and Sequenced Packet Exchange. File and print services ran on the NetWare Core Protocol over IPX, as did Routing Information Protocol, NetWare uses Novell DOS as a boot loader. Novell DOS is similar to MS-DOS and IBM PC DOS, but no license for DOS is required. Novell had already acquired Kanwal Rekhis company Excelan, which manufactured smart Ethernet cards and commercialized the Internet protocol TCP/IP, Novell did extremely well throughout the 1980s. It aggressively expanded its share by selling its expensive Ethernet cards at cost. By 1990, Novell had an almost monopolistic position in NOS for any business requiring a network, with this market leadership, Novell began to acquire and build services on top of its NetWare operating platform
4.
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
5.
Open-source model
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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
6.
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
7.
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
8.
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
9.
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
10.
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
11.
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
12.
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
13.
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
14.
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
15.
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
16.
Gary Kildall
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Gary Arlen Kildall was an American computer scientist and microcomputer entrepreneur who created the CP/M operating system and founded Digital Research, Inc. Kildall was one of the first people to see microprocessors as fully capable computers rather than equipment controllers and he also co-hosted the PBS TV show The Computer Chronicles. Although his career in computing spanned more than two decades, he is remembered in connection with IBMs unsuccessful attempt in 1980 to license CP/M for the IBM PC. Gary Kildall was born and grew up in Seattle, Washington and his father, Joseph Kildall, was a captain of Norwegian heritage. His mother Emma was half-Swedish—Garys grandmother was born in Långbäck, Sweden, in Skellefteå Municipality, Gary attended the University of Washington hoping to become a mathematics teacher, but became increasingly interested in computer technology. After receiving his degree, he fulfilled a draft obligation to the United States Navy by teaching at the Naval Postgraduate School in Monterey, being within an hours drive of Silicon Valley, Kildall heard about the first commercially available microprocessor, the Intel 4004. He bought one of the processors and began writing programs for it. To learn more about the processors, he worked at Intel as a consultant on his days off, Kildall briefly returned to UW and finished his doctorate in computer science in 1972, then resumed teaching at NPS. Intel lent him systems using the 8008 and 8080 processors, and in 1973, he developed the first high-level programming language for microprocessors, called PL/M. He created CP/M the same year to enable the 8080 to control a floppy drive and he demonstrated CP/M to Intel, but Intel had little interest and chose to market PL/M instead. Kildall and his wife Dorothy established a company, originally called Intergalactic Digital Research, Digital Research licensed CP/M for the IMSAI8080, a popular clone of the Altair 8800. As more manufacturers licensed CP/M, it became a de facto standard and had to support a number of hardware variations. In response, Kildall pioneered the concept of a BIOS, a set of programs stored in the computer hardware that enabled CP/M to run on different systems without modification. CP/Ms quick success took Kildall by surprise, and he was slow to update it for high density floppy disks, after hardware manufacturers talked about creating a rival operating system, Kildall started a rush project to develop CP/M2. By 1981, at the peak of its popularity, CP/M ran on 3,000 different computer models and DRI had $5.4 million in yearly revenues. IBM, presided by John R. Opel, approached Digital Research in 1980, at Bill Gates suggestion, before the IBM representatives would explain the purpose of their visit, they insisted that Dorothy sign a non-disclosure agreement. On the advice of DRI attorney Gerry Davis, Dorothy refused to sign the agreement without Garys approval, various reasons have been given for the two companies failing to reach an agreement. DRI, which had only a few products, might have been unwilling to sell its product to IBM for a one-time payment rather than its usual royalty-based plan
17.
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
18.
Intel 8080
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The Intel 8080 was the second 8-bit microprocessor designed and manufactured by Intel and was released in April 1974. It was an extended and enhanced variant of the earlier 8008 design, a slightly faster variant 8080A-1 became available later with clock frequency limit up to 3.125 MHz. The 8080 was successful enough that compatibility at the language level became a design requirement for the 8086 when design for it was started in 1976. This also means that the 8080 indirectly influenced the ubiquitous 32-bit and 64-bit x86 architectures of today, the Intel 8080 was the successor to the 8008. It used the basic instruction set and register model as the 8008. Every instruction in the 8008 has an equivalent instruction in the 8080, the 8080 also added a few 16-bit operations to its instruction set as well. Whereas the 8008 required the use of the HL register pair to indirectly access its 14-bit memory space, in addition, the internal 7-level push-down call stack of the 8008 was replaced by a dedicated 16-bit stack pointer register. The 8080s large 40-pin DIP packaging permitted it to provide a 16-bit address bus and it also has a 16-bit stack pointer to memory, and a 16-bit program counter. The processor maintains internal flag bits which indicates the results of arithmetic, conditional branch instructions test the various flag status bits. The flags can be copied as a group to the accumulator, the A accumulator and the flags together are called the PSW register or program status word. As with many other 8-bit processors, all instructions are encoded in a single byte, some of them are followed by one or two bytes of data, which can be an immediate operand, a memory address, or a port number. Like larger processors, it has automatic CALL and RET instructions for multi-level procedure calls and returns, there are also eight one-byte call instructions for subroutines located at the fixed addresses 00h, 08h, 10h. and 38h. These were intended to be supplied by external hardware in order to invoke a corresponding interrupt-service routine, the most sophisticated command is XTHL, which is used for exchanging the register pair HL with the value stored at the address indicated by the stack pointer. Most 8-bit operations can only be performed on the 8-bit accumulator, for 8-bit operations with two operands, the other operand can be either an immediate value, another 8-bit register, or a memory byte addressed by the 16-bit register pair HL. Direct copying is supported between any two 8-bit registers and between any 8-bit register and an HL-addressed memory byte, due to the regular encoding of the MOV instruction, there are redundant codes to copy a register into itself, which were of little use, except for delays. However, what would have been a copy from the HL-addressed cell into itself is used to encode the halt instruction. The XCHG instruction exchanges the values of the HL and DE register pairs, by adding HL to itself, it is possible to achieve the same result as a 16-bit arithmetical left shift with one instruction. The 8080 supported up to 256 input/output ports, accessed via dedicated I/O instructions—taking port addresses as operands and this I/O mapping scheme was regarded as an advantage, as it freed up the processors limited address space
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Zilog Z80
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The Z80 CPU is an 8-bit based microprocessor. It was introduced by Zilog in 1976 as the companys first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his employees at Zilog from early 1975 until March 1976. With the revenue from the Z80, the company built its own chip factories, the Zilog Z80 was a software compatible extension and enhancement of the Intel 8080 and, like it, was mainly aimed at embedded systems. In the early 1980s, the Z80 was the most commonly used CPU of all time, Zilog licensed the Z80 to the US-based Synertek and Mostek, that had helped them with initial production, as well as to a European second source manufacturer, SGS. The design was copied also by several Japanese, East European and Russian manufacturers and this enabled the Z80 to gain acceptance in the world market since large companies like NEC, Toshiba, Sharp, and Hitachi, started to manufacture the device. The Z80 came about when physicist Federico Faggin left Intel at the end of 1974 to found Zilog with Ralph Ungermann, at Fairchild Semiconductor, and later at Intel, Faggin had been working on fundamental transistor and semiconductor manufacturing technology. He also developed the design methodology used for memories and microprocessors at Intel and led the work on the Intel 4004. Masatoshi Shima, the logic and transistor level-designer of the 4004. By March 1976, Zilog had developed the Z80 as well as an accompanying assembler based development system for its customers, and by July 1976, early Z80s were manufactured by Synertek and Mostek, before Zilog had its own manufacturing factory ready, in late 1976. Masatoshi Shima designed most of the microarchitecture as well as the gate and transistor levels of the Z80 CPU, assisted by a number of engineers. CEO Federico Faggin was actually involved in the chip layout work. Faggin worked 80 hours a week in order to meet the tight schedule given by the financial investors, a non maskable interrupt which can be used to respond to power down situations and/or other high priority events. Two separate register files, which could be switched, to speed up response to interrupts such as fast asynchronous event handlers or a multitasking dispatcher. Although they were not intended as extra registers for general code, less hardware required for power supply, clock generation and interface to memory and I/O Single 5-volt power supply. A built-in DRAM refresh mechanism that would otherwise have to be provided by external circuitry, a special reset function which clears only the program counter so that a single Z80 CPU could be used in a development system such as an in-circuit emulator. The Z80 took over from the 8080 and its offspring, the 8085, in the processor market, perhaps a key to the initial success of the Z80 was the built-in DRAM refresh, and other features which allowed systems to be built with fewer support chips. For the original NMOS design, the specified upper frequency limit increased successively from the introductory 2.5 MHz, via the well known 4 MHz
20.
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
21.
Intel 8088
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The Intel 8088 microprocessor is a variant of the Intel 8086. Introduced on July 1,1979, the 8088 had an 8-bit external data bus instead of the 16-bit bus of the 8086, the 16-bit registers and the one megabyte address range were unchanged, however. In fact, according to the Intel documentation, the 8086 and 8088 have the execution unit —only the bus interface unit is different. The original IBM PC was based on the 8088, the 8088 was designed in Israel, at Intels Haifa laboratory, as were a large number of Intels processors. The prefetch queue of the 8088 was shortened to four bytes, from the 8086s six bytes, and these modifications of the basic 8086 design were one of the first jobs assigned to Intels then new design office and laboratory in Haifa, Israel. Later followed the 80C88, a fully static CHMOS design, which could operate with clock speeds from 0 to 8 MHz, there were also several other, more or less similar, variants from other manufacturers. For instance, the NEC V20 was a pin compatible and slightly faster variant of the 8088, successive NEC8088 compatible processors would run at up to 16 MHz. In 1984, Commodore International signed a deal to manufacture the 8088 for use in a licensed Dynalogic Hyperion clone, when announced, the list price of the 8088 was US $124.80. The 8088 is architecturally similar to the 8086. The main difference is there are only 8 data lines instead of the 8086s 16 lines. All of the pins of the device perform the same function as they do with the 8086 with two exceptions. First, pin 34 is no longer BHE, instead it outputs a maximum mode status, SSO. Combined with the IO/M and DT/R signals, the bus cycles can be decoded, the second change is the pin that signals if a memory access or input/output access is being made has had it sense reversed. The pin on the 8088 is IO/M, on the 8086 part it is IO/M. The reason for the reversal is that it makes the 8088 compatible with the 8085. 33–1 million instructions per second. The speed of the unit and the bus of the 8086 CPU was well balanced, with a typical instruction mix. Cutting down the bus to 8 bits made it a bottleneck in the 8088. With the speed of instruction fetch reduced by 50% in the 8088 as compared to the 8086, when the queue is empty, instructions take as long to complete as they take to fetch
22.
IBM
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International Business Machines Corporation is an American multinational technology company headquartered in Armonk, New York, United States, with operations in over 170 countries. The company originated in 1911 as the Computing-Tabulating-Recording Company and was renamed International Business Machines in 1924, IBM manufactures and markets computer hardware, middleware and software, and offers hosting and consulting services in areas ranging from mainframe computers to nanotechnology. IBM is also a research organization, holding the record for most patents generated by a business for 24 consecutive years. IBM has continually shifted its business mix by exiting commoditizing markets and focusing on higher-value, also in 2014, IBM announced that it would go fabless, continuing to design semiconductors, but offloading manufacturing to GlobalFoundries. Nicknamed Big Blue, IBM is one of 30 companies included in the Dow Jones Industrial Average and one of the worlds largest employers, with nearly 380,000 employees. Known as IBMers, IBM employees have been awarded five Nobel Prizes, six Turing Awards, ten National Medals of Technology, in the 1880s, technologies emerged that would ultimately form the core of what would become International Business Machines. On June 16,1911, their four companies were amalgamated in New York State by Charles Ranlett Flint forming a fifth company, the Computing-Tabulating-Recording Company based in Endicott, New York. The five companies had 1,300 employees and offices and plants in Endicott and Binghamton, New York, Dayton, Ohio, Detroit, Michigan, Washington, D. C. and Toronto. They manufactured machinery for sale and lease, ranging from commercial scales and industrial time recorders, meat and cheese slicers, to tabulators and punched cards. Thomas J. Watson, Sr. fired from the National Cash Register Company by John Henry Patterson, called on Flint and, Watson joined CTR as General Manager then,11 months later, was made President when court cases relating to his time at NCR were resolved. Having learned Pattersons pioneering business practices, Watson proceeded to put the stamp of NCR onto CTRs companies and his favorite slogan, THINK, became a mantra for each companys employees. During Watsons first four years, revenues more than doubled to $9 million, Watson had never liked the clumsy hyphenated title of the CTR and in 1924 chose to replace it with the more expansive title International Business Machines. By 1933 most of the subsidiaries had been merged into one company, in 1937, IBMs tabulating equipment enabled organizations to process unprecedented amounts of data, its clients including the U. S. During the Second World War the company produced small arms for the American war effort, in 1949, Thomas Watson, Sr. created IBM World Trade Corporation, a subsidiary of IBM focused on foreign operations. In 1952, he stepped down after almost 40 years at the company helm, in 1957, the FORTRAN scientific programming language was developed. In 1961, IBM developed the SABRE reservation system for American Airlines, in 1963, IBM employees and computers helped NASA track the orbital flight of the Mercury astronauts. A year later it moved its headquarters from New York City to Armonk. The latter half of the 1960s saw IBM continue its support of space exploration, on April 7,1964, IBM announced the first computer system family, the IBM System/360
23.
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
24.
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
25.
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
26.
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
27.
MS-DOS
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MS-DOS is a discontinued operating system for x86-based personal computers mostly developed by Microsoft. MS-DOS resulted from a request in 1981 by IBM for a system to use in its IBM PC range of personal computers. Microsoft quickly bought the rights to 86-DOS from Seattle Computer Products, IBM licensed and released it in August 1981 as PC DOS1.0 for use in their PCs. During its life, several competing products were released for the x86 platform and it was also the underlying basic operating system on which early versions of Windows ran as a GUI. It is a operating system, and consumes negligible installation space. MS-DOS was a form of 86-DOS – owned by Seattle Computer Products. This first version was shipped in August 1980, Microsoft, which needed an operating system for the IBM Personal Computer hired Tim Paterson in May 1981 and bought 86-DOS1.10 for $75,000 in July of the same year. Microsoft kept the number, but renamed it MS-DOS. They also licensed MS-DOS1. 10/1.14 to IBM, within a year Microsoft licensed MS-DOS to over 70 other companies. It was designed to be an OS that could run on any 8086-family computer, thus, there were many different versions of MS-DOS for different hardware, and there is a major distinction between an IBM-compatible machine and an MS-DOS machine. This design would have worked well for compatibility, if application programs had only used MS-DOS services to perform device I/O, Microsoft omitted multi-user support from MS-DOS because Microsofts Unix-based operating system, Xenix, was fully multi-user. After the breakup of the Bell System, however, AT&T Computer Systems started selling UNIX System V, believing that it could not compete with AT&T in the Unix market, Microsoft abandoned Xenix, and in 1987 transferred ownership of Xenix to the Santa Cruz Operation. On 25 March 2014, Microsoft made the code to SCP MS-DOS1.25, as an April Fools joke in 2015, Microsoft Mobile launched a Windows Phone application called MS-DOS Mobile which was presented as a new mobile operating system and worked similar to MS-DOS. Version 3.1 – Support for Microsoft Networks Version 3.2 – First version to support 3.5 inch,720 kB floppy drives and diskettes. Version 3.21 Version 3.22 – Version 3.25 Version 3.3 – First version to support 3.5 inch,1.44 MB floppy drives and diskettes, Version 3. 3a Version 3.31 – supports FAT16B and larger drives. MS-DOS4.0 and MS-DOS4.1 – A separate branch of development with additional multitasking features and it is unrelated to any later versions, including versions 4.00 and 4.01 listed below MS-DOS4. x – includes a graphical/mouse interface. It had many bugs and compatibility issues. Version 4.00 – First version to support a hard disk partition that is greater than 32 MiB. Version 4.01 – Microsoft rewritten Version 4.00 released under MS-DOS label, First version to introduce volume serial number when formatting hard disks and floppy disks
28.
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
29.
Pacific Grove, California
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Pacific Grove is a coastal city in Monterey County, California in the United States. The United States Census Bureau estimated its 2013 population at 15,504, Pacific Grove is located between Point Pinos and Monterey. Pacific Grove is known for its Victorian homes, Asilomar State Beach, the city is endowed with more historical houses per capita than anywhere else in California. Seventy-five percent of the homes in Pacific Grove are considered historical, some of them have been turned into bed and breakfast inns. The city is known as the location of the Point Pinos Lighthouse. The Pacific Grove Museum of Natural History and Pacific Grove Art Center are located in the historic downtown, Pacific Grove was also the main filming location for Roger Spottiswoodes 1989 film Turner & Hooch as well as A Summer Place, starring Sandra Dee. In prehistoric times the Rumsen were one of the linguistically distinct Ohlone groups of the Monterey Bay Area who inhabited the area now known as Pacific Grove and this tribe subsisted with hunting, fishing and gathering in what has been deduced as a biologically rich Monterey Peninsula. In time, the butterflies, fragrant pines and fresh sea air brought others to the Pacific Grove Retreat to rest, the initial camp meeting of the Pacific Coast branch of the Chautauqua Literary and Scientific Circle was held in Pacific Grove in June 1879. Modeled after the Methodist Sunday school teachers training camp established in 1874 at Chautauqua Lake, New York, in November 1879, after the summer campers returned home, Robert Louis Stevenson wandered into the deserted campgrounds, I have never been in any place so dreamlike. Indeed, it was not so much like a town as like a scene upon the stage by daylight. The Pacific Grove post office opened in 1886, closed later that year, Pacific Grove, like Carmel-by-the-Sea and Monterey, became an artists haven in the 1890s and subsequent period. Artists of the En plein air school in both Europe and the United States were seeking a venue which had natural beauty, so that Pacific Grove was a magnet for this movement. William Adam was an English painter who first moved to Monterey, at about the same time Eugen Neuhaus, a German painter, arrived in Pacific Grove with his new bride. The Asilomar Conference Grounds are located at the edge of Pacific Grove. Asilomar opened in 1913 as a YWCA summer retreat it now belongs to the California State Park System, thirteen buildings on these grounds were designed by the architect Julia Morgan, who also designed Hearst Castle. For a number of years, John Steinbeck lived in a cottage in Pacific Grove owned by his father, Ernest, the cottage still stands on a quiet side street at 147 11th St. without any plaque or special sign, virtually overlooked by most Steinbeck fans. Another Steinbeck related house is at 222 Central Ave, which was his grandmothers house, a golden statue of Steinbeck in the front yard stood for years before it was removed. In Steinbecks book Sweet Thursday, a chapter is dedicated to describing a rivalry that arose among the residents over the game of roque
30.
Monterey, California
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The City of Monterey in Monterey County is located on the southern edge of Monterey Bay, in the Northern Portion of Californias Central Coast. It stands at an elevation of 26 feet above sea level, the 2010 census recorded a population of 27,810. Monterey was the capital of Alta California under both Spain and Mexico and it was the only port of entry for taxable goods in California. In 1846 the U. S. flag was raised over the Customs House, the city had Californias first theater, public building, public library, publicly funded school, printing press, and newspaper. The city and surrounding area have attracted artists since the late 19th century, until the 1950s, there was an abundant fishery. Among Montereys notable present-day attractions are the Monterey Bay Aquarium, Cannery Row, Fishermans Wharf, long before the arrival of Spanish explorers, the Rumsen Ohlone tribe, one of seven linguistically distinct Ohlone groups in California, inhabited the area now known as Monterey. They subsisted by hunting, fishing and gathering food on and around the biologically rich Monterey Peninsula, researchers have found a number of shell middens in the area and, based on the archaeological evidence, concluded the Ohlones primary marine food consisted at various times of mussels and abalone. A number of sites have been located along about 12 miles of rocky coast on the Monterey Peninsula from the current site of Fishermans Wharf in Monterey to Carmel. In 1602, Spanish maritime explorer Sebastian Vizcaino recorded the name Bahía de Monterrey, Vizcaino landed at the southern end of the bay and described a great port, suitable for use as an anchorage by southbound Manila galleons. Vizcaino also noted and named the Point of Pines, all other uses of the name Monterey derive from Vizcainos name for the bay. Variants of the name are recorded as Monte Rey and Montery. In 1769, the first European land exploration of Alta California, for some reason, the explorers failed to recognize the place when they came to it on October 1,1769. The party continued north as far as San Francisco Bay before turning back, on the return journey, they camped near one of Montereys lagoons on November 27, still not convinced they had found the place Vizcaino had described. Franciscan missionary Juan Crespí noted in his diary, We halted in sight of the Point of Pines and camped near a lagoon which has rather muddy water. Portolá returned by land to Monterey the next year, having concluded that he must have been at Vizcainos Port of Monterey after all, the land party was met at Monterey by Junípero Serra who traveled by sea. Portolá erected the Presidio of Monterey to defend the port and, on June 3,1770, Portolá returned to Mexico, replaced in Monterey by Captain Pedro Fages, who had been third in command on the exploratory expeditions. Fages became the governor of Alta California, serving from 1770 to 1774. Serras missionary aims soon came into conflict with Fages and the soldiers, the existing wood and adobe building became the chapel for the Presidio
31.
Newbury, Berkshire
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Newbury /ˈnjuːbəri/ is a historic market town and the principal town in the west of Berkshire, England and has its own civil parish as well as the administrative headquarters of West Berkshire. It spans both sides of the River Kennet and the Kennet and Avon Canal, and has a town centre spread around its large market square. Newbury is famous for its racecourse, and as the headquarters of Vodafone UK, the town is located in the valley of the River Kennet,26 miles south of Oxford,25 miles north of Winchester,27 miles south east of Swindon and 20 miles west of Reading. Newbury lies on the edge of the picturesque Berkshire Downs, part of the North Wessex Downs Area of outstanding natural beauty and it lies in south central West Berkshire,3 miles north of the Hampshire/ West Berkshire county boundary. In the suburban village of Donnington lies the part-ruined Donnington Castle, to the south is a narrower range of hills including Walbury Hill and a few private landscape gardens and mansions such as Highclere Castle. Together with the town of Thatcham,3 miles distant. There was a Mesolithic settlement at Newbury, artefacts were recovered from the Greenham Dairy Farm in 1963, and the Faraday Road site in 2002. Additional material was found in excavations along the route of the Newbury Bypass, Newbury was founded late in the 11th century following the Norman conquest as a new borough, hence its name. Although there are references to the borough that predate the Domesday Survey it is not mentioned by name in the survey. However, its existence within the manor of Ulvritone is evident from the rise in value of that manor at a time when most manors were worth less than in Saxon times. In 1086 the Domesday Book assesses the borough as having land for 12 ploughs,2 mills, woodland for 25 pigs,11 villeins,11 bordars, and 51 enclosures rendering 70s 7d. Doubt has been cast over the existence of Newbury Castle, but the town did have connections and was visited a number of times by King John. Historically, the economic foundation was the cloth trade. This is reflected in the person of the 16th century cloth magnate, Jack of Newbury, the proprietor of what may well have been the first factory in England, and the later tale of the Newbury Coat. The latter was the outcome of a bet as to whether a suit could be produced by the end of the day from wool taken from a sheeps back at the beginning. The local legend was immortalized in a humorous novel by Elizabethan writer Thomas Deloney. Newbury was the site of two battles during the English Civil War, the First Battle of Newbury in 1643, the nearby Donnington Castle was reduced to a ruin in the aftermath of the second battle. The disruption of trade during the war, compounded by a collapse of the local cloth trade in the late 16th century
32.
Hungerford
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Hungerford is a historic market town and civil parish in Berkshire, England, centred 8 miles west of Newbury,9 miles east of Marlborough,30 miles northeast of Salisbury and 67 miles west of London. Its amenities include shops, cafés, restaurants, schools and sports teams or clubs in the national sports. Hungerford is an abbreviation and vowel shift from a Saxon name meaning Hanging Wood Ford. The town’s symbol is the star and crescent moon. The place does not occur in the Domesday Book of 1086, by 1241, it called itself a borough. In the late 14th century, John of Gaunt was medieval lord of the manor, during the English Civil War, the Earl of Essex and his army spent the night here in June 1644. In October of the year, the Earl of Manchester’s cavalry were also quartered in the town. Then, in the November, the King’s forces arrived in Hungerford on their way to Abingdon, during the Glorious Revolution of 1688, William of Orange was offered the Crown of England while staying at the Bear Inn in Hungerford. The Hungerford land south of the Kennet was for the centuries, until an 18th-century widespread growth in cultivation the area, st. Lawrences parish church stands next to the Kennet and Avon Canal. It was rebuilt in 1814–1816 by John Pinch the elder in Gothic Revival style, in the late 19th century, two policeman were shot by poachers in Eddington. Their memorial crosses still stand where they fell, the Hungerford massacre occurred on 19 August 1987. All of his victims were shot in the town or in nearby Savernake Forest, a report on this incident was commissioned by Home Secretary Douglas Hurd from the Chief Constable of Thames Valley Police, Colin Smith. It is one of three highly costly firearms atrocities in terms of lives since the invention of such rapid fire weapons, the other two being the Dunblane massacre and Cumbria shootings. The massacre led to the Firearms Act 1988, which banned the ownership of semi-automatic centre-fire rifles, the Hungerford Report had demonstrated that Ryans collection of weapons was legally licensed. Hungerford is a parish, covering the town of Hungerford. Parish council responsibilities are undertaken by Hungerford Town Council, which consists of fifteen councillors and committee members. The mayor is elected from amongst their numbers, the parish forms part of the district administered by the unitary authority of West Berkshire, and local government responsibilities are shared between the town council and unitary authority. Hungerford is part of the Newbury parliamentary constituency and its MP is the Conservative Richard Benyon, son of Sir William Benyon of Englefield House
33.
Compaq MS-DOS 3.31
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MS-DOS is a discontinued operating system for x86-based personal computers mostly developed by Microsoft. MS-DOS resulted from a request in 1981 by IBM for a system to use in its IBM PC range of personal computers. Microsoft quickly bought the rights to 86-DOS from Seattle Computer Products, IBM licensed and released it in August 1981 as PC DOS1.0 for use in their PCs. During its life, several competing products were released for the x86 platform and it was also the underlying basic operating system on which early versions of Windows ran as a GUI. It is a operating system, and consumes negligible installation space. MS-DOS was a form of 86-DOS – owned by Seattle Computer Products. This first version was shipped in August 1980, Microsoft, which needed an operating system for the IBM Personal Computer hired Tim Paterson in May 1981 and bought 86-DOS1.10 for $75,000 in July of the same year. Microsoft kept the number, but renamed it MS-DOS. They also licensed MS-DOS1. 10/1.14 to IBM, within a year Microsoft licensed MS-DOS to over 70 other companies. It was designed to be an OS that could run on any 8086-family computer, thus, there were many different versions of MS-DOS for different hardware, and there is a major distinction between an IBM-compatible machine and an MS-DOS machine. This design would have worked well for compatibility, if application programs had only used MS-DOS services to perform device I/O, Microsoft omitted multi-user support from MS-DOS because Microsofts Unix-based operating system, Xenix, was fully multi-user. After the breakup of the Bell System, however, AT&T Computer Systems started selling UNIX System V, believing that it could not compete with AT&T in the Unix market, Microsoft abandoned Xenix, and in 1987 transferred ownership of Xenix to the Santa Cruz Operation. On 25 March 2014, Microsoft made the code to SCP MS-DOS1.25, as an April Fools joke in 2015, Microsoft Mobile launched a Windows Phone application called MS-DOS Mobile which was presented as a new mobile operating system and worked similar to MS-DOS. Version 3.1 – Support for Microsoft Networks Version 3.2 – First version to support 3.5 inch,720 kB floppy drives and diskettes. Version 3.21 Version 3.22 – Version 3.25 Version 3.3 – First version to support 3.5 inch,1.44 MB floppy drives and diskettes, Version 3. 3a Version 3.31 – supports FAT16B and larger drives. MS-DOS4.0 and MS-DOS4.1 – A separate branch of development with additional multitasking features and it is unrelated to any later versions, including versions 4.00 and 4.01 listed below MS-DOS4. x – includes a graphical/mouse interface. It had many bugs and compatibility issues. Version 4.00 – First version to support a hard disk partition that is greater than 32 MiB. Version 4.01 – Microsoft rewritten Version 4.00 released under MS-DOS label, First version to introduce volume serial number when formatting hard disks and floppy disks
