William Henry Gates III is an American business magnate, author and humanitarian. He is best known as the principal founder of Microsoft Corporation. During his career at Microsoft, Gates held the positions of chairman, CEO and chief software architect, while being the largest individual shareholder until May 2014. In 1975, Gates and Paul Allen launched Microsoft, which became the world's largest PC software company. Gates led the company as chief executive officer until stepping down in January 2000, but he remained as chairman and created the position of chief software architect for himself. In June 2006, Gates announced that he would be transitioning from full-time work at Microsoft to part-time work and full-time work at the Bill & Melinda Gates Foundation, the private charitable foundation that he and his wife, Melinda Gates, established in 2000, he transferred his duties to Ray Ozzie and Craig Mundie. He stepped down as chairman of Microsoft in February 2014 and assumed a new post as technology adviser to support the newly appointed CEO Satya Nadella.
Gates is one of the best-known entrepreneurs of the personal computer revolution. He has been criticized for his business tactics; this opinion has been upheld by numerous court rulings. Since 1987, Gates has been included in the Forbes list of the world's wealthiest people, an index of the wealthiest documented individuals and ranking against those with wealth, not able to be ascertained. From 1995 to 2017, he held the Forbes title of the richest person in the world all but four of those years, held it from March 2014 to July 2017, with an estimated net worth of US$89.9 billion as of October 2017. However, on July 27, 2017, since October 27, 2017, he has been surpassed by Amazon founder and CEO Jeff Bezos, who had an estimated net worth of US$90.6 billion at the time. As of August 6, 2018, Gates had a net worth of $95.4 billion, making him the second-richest person in the world, behind Bezos. In his career and since leaving Microsoft, Gates pursued a number of philanthropic endeavors, he donated large amounts of money to various charitable organizations and scientific research programs through the Bill & Melinda Gates Foundation, reported to be the world's largest private charity.
In 2009, Gates and Warren Buffett founded The Giving Pledge, whereby they and other billionaires pledge to give at least half of their wealth to philanthropy. The foundation works to save lives and improve global health, is working with Rotary International to eliminate polio. Gates was born in Seattle, Washington, on October 28, 1955, he is the son of Mary Maxwell Gates. His ancestry includes English, German and Scots-Irish, his father was a prominent lawyer, his mother served on the board of directors for First Interstate BancSystem and the United Way. Gates' maternal grandfather was J. W. Maxwell, a national bank president. Gates has one older sister, a younger sister, Libby, he is the fourth of his name in his family, but is known as William Gates III or "Trey" because his father had the "II" suffix. The family lived in the Sand Point area of Seattle in a home, once damaged by a rare tornado when Gates was seven years old. Early on in his life, Gates observed; when Gates was young, his family attended a church of the Congregational Christian Churches, a Protestant Reformed denomination.
The family encouraged competition. There was always a reward for winning and there was always a penalty for losing". At 13, he enrolled in the Lakeside School, a private preparatory school and wrote his first software program; when Gates was in the eighth grade, the Mothers' Club at the school used proceeds from Lakeside School's rummage sale to buy a Teletype Model 33 ASR terminal and a block of computer time on a General Electric computer for the school's students. Gates took an interest in programming the GE system in BASIC, was excused from math classes to pursue his interest, he wrote his first computer program on this machine: an implementation of tic-tac-toe that allowed users to play games against the computer. Gates was fascinated by the machine; when he reflected back on that moment, he said, "There was just something neat about the machine." After the Mothers Club donation was exhausted, he and other students sought time on systems including DEC PDP minicomputers. One of these systems was a PDP-10 belonging to Computer Center Corporation, which banned four Lakeside students – Gates, Paul Allen, Ric Weiland, Kent Evans – for the summer after it caught them exploiting bugs in the operating system to obtain free computer time.
At the end of the ban, the four students offered to find bugs in CCC's software in exchange for extra computer time. Rather than use the system via Teletype, Gates went to CCC's offices and studied source code for various programs that ran on the system, including programs in Fortran and machine language; the arrangement with CCC continued until 1970. The following year, Information Sciences, Inc. hired the four Lakeside students to write a payroll program in COBOL, providing them computer time and royalties. After his administrators became aware of his programming abilities, Gates wrote the school's student information system software to schedule students in classes, he modified the code so that he was placed in classes with "a disproportionate number of interesting girls." He stated that "it
The IBM System/360 is a family of mainframe computer systems, announced by IBM on April 7, 1964, delivered between 1965 and 1978. It was the first family of computers designed to cover the complete range of applications, from small to large, both commercial and scientific; the design made a clear distinction between architecture and implementation, allowing IBM to release a suite of compatible designs at different prices. All but the incompatible Model 44 and the most expensive systems used microcode to implement the instruction set, which featured 8-bit byte addressing and binary and floating-point calculations; the launch of the System/360 family introduced IBM's Solid Logic Technology, a new technology, the start of more powerful but smaller computers. The slowest System/360 model announced in 1964, the Model 30, could perform up to 34,500 instructions per second, with memory from 8 to 64 KB. High performance models came later; the 1967 IBM System/360 Model 91 could do up to 16.6 million instructions per second.
The larger 360 models could have up to 8 MB of main memory, though main memory that big was unusual—a large installation might have as little as 256 KB of main storage, but 512 KB, 768 KB or 1024 KB was more common. Up to 8 megabytes of slower Large Capacity Storage was available; the IBM 360 was successful in the market, allowing customers to purchase a smaller system with the knowledge they would always be able to migrate upward if their needs grew, without reprogramming of application software or replacing peripheral devices. Many consider the design one of the most successful computers in history, influencing computer design for years to come; the chief architect of System/360 was Gene Amdahl, the project was managed by Fred Brooks, responsible to Chairman Thomas J. Watson Jr; the commercial release was piloted by another of Watson's lieutenants, John R. Opel, who managed the launch of IBM’s System 360 mainframe family in 1964. Application-level compatibility for System/360 software is maintained to the present day with the System z mainframe servers.
Contrasting with at-the-time normal industry practice, IBM created an entire new series of computers, from small to large, low- to high-performance, all using the same instruction set. This feat allowed customers to use a cheaper model and upgrade to larger systems as their needs increased without the time and expense of rewriting software. Before the introduction of System/360, business and scientific applications used different computers with different instruction sets and operating systems. Different-sized computers had their own instruction sets. IBM was the first manufacturer to exploit microcode technology to implement a compatible range of computers of differing performance, although the largest, models had hard-wired logic instead; this flexibility lowered barriers to entry. With most other vendors customers had to choose between machines they could outgrow and machines that were too powerful and thus too costly; this meant that many companies did not buy computers. IBM announced a series of six computers and forty common peripherals.
IBM delivered fourteen models, including rare one-off models for NASA. The least expensive model was the Model 20 with as little as 4096 bytes of core memory, eight 16-bit registers instead of the sixteen 32-bit registers of other System/360 models, an instruction set, a subset of that used by the rest of the range; the initial announcement in 1964 included Models 30, 40, 50, 60, 62, 70. The first three were low- to middle-range systems aimed at the IBM 1400 series market. All three first shipped in mid-1965; the last three, intended to replace the 7000 series machines, never shipped and were replaced with the 65 and 75, which were first delivered in November 1965, January 1966, respectively. Additions to the low-end included models 20, 22, 25; the Model 20 had several sub-models. The Model 22 was a recycled Model 30 with minor limitations: a smaller maximum memory configuration, slower I/O channels, which limited it to slower and lower-capacity disk and tape devices than on the 30; the Model 44 was a specialized model, designed for scientific computing and for real-time computing and process control, featuring some additional instructions, with all storage-to-storage instructions and five other complex instructions eliminated.
A succession of high-end machines included the Model 67, 85, 91, 95, 195. The 85 design was intermediate between the System/360 line and the follow-on System/370 and was the basis for the 370/165. There was a System/370 version of the 195; the implementations differed using different native data path widths, presence or absence of microcode, yet were compatible. Except where documented, the models were architecturally compatible; the 91, for example, was designed for scientific computing and provided out-of-order instruction execution, but lacked the decimal instruction set used in commercial applications. New features could be added without violating architectural definitions: the 65 had a dual-processor version with extensions for inter-CPU signalling. Models 44, 75, 91, 95, 195 were implemented with hardwired logic, rather than microcoded as
Altair BASIC is a discontinued interpreter for the BASIC programming language that ran on the MITS Altair 8800 and subsequent S-100 bus computers. It was Microsoft's first product, distributed by MITS under a contract. Altair BASIC was the start of the Microsoft BASIC product range. Bill Gates recalls that, when he and Paul Allen read about the Altair in the January 1975 issue of Popular Electronics, they understood that the price of computers would soon drop to the point that selling software for them would be a profitable business. Gates believed that, by providing a BASIC interpreter for the new computer, they could make it more attractive to hobbyists, they contacted MITS founder Ed Roberts, told him that they were developing an interpreter, asked whether he would like to see a demonstration. This followed the questionable engineering industry practice of a trial balloon, an announcement of a non-existent product to gauge interest. Roberts agreed to meet them for a demonstration in a few weeks, in March 1975.
Gates and Allen had neither an interpreter nor an Altair system on which to develop and test one. However, Allen had written an Intel 8008 emulator for their previous venture Traf-O-Data that ran on a PDP-10 time-sharing computer, he adapted this emulator based on the Altair programmer guide, they developed and tested the interpreter on Harvard's PDP-10. Harvard officials were not pleased when they found out, but there was no written policy that covered the use of this computer. Gates and Allen bought computer time from a timesharing service in Boston to complete their BASIC program debugging, they hired Harvard student Monte Davidoff to write floating-point arithmetic routines for the interpreter, a feature not available in many of its competitors. The finished interpreter, including its own I/O system and line editor, fit in only four kilobytes of memory, leaving plenty of room for the interpreted program. In preparation for the demo, they stored the finished interpreter on a punched tape that the Altair could read, Paul Allen flew to Albuquerque.
On final approach, Allen realized that they had forgotten to write a bootstrap program to read the tape into memory. Writing in 8080 machine language, Allen finished the program. Only when they loaded the program onto an Altair and saw a prompt asking for the system's memory size did Gates and Allen know that their interpreter worked on the Altair hardware, they made a bet on who could write the shortest bootstrap program, Gates won. Roberts agreed to distribute the interpreter, he hired Gates and Allen to maintain and improve it, causing Gates to take a leave of absence from Harvard. They produced several versions: the original 4K BASIC and 8K BASIC, Extended BASIC, Extended ROM BASIC, Disk BASIC; the smallest version, 4K BASIC, was able to run within a 4k RAM machine, leaving only about 790 bytes free for program code. To make the language fit in such a small space, the 4K version lacked string handling and stripped out a number of the mathematical functions; these were added back into the 8K BASIC, which had the string library, a larger set of math functions including RND for random numbers, boolean operators, PEEK and POKE.
The 8K version is the basis for most versions of BASIC during the home computer era. Extended BASIC added PRINT USING and basic disk commands, while Disk BASIC further extended the disk commands to allow raw I/O. In October 1975, 4K BASIC sold for $150, 8K BASIC for $200, Extended BASIC for $350; the prices were discounted to $60, $75, $150 for those who purchased "8K of Altair memory, an Altair I/O board." The language versions were available on cassette tape. As they expected, the Altair was popular with hobbyists such as the Homebrew Computer Club. Altair BASIC, as MITS' preferred BASIC interpreter, was popular. However, the hobbyists took a "share-alike" approach to software and thought nothing of copying the BASIC interpreter for other hobbyists. Homebrew member Dan Sokol was prolific. Gates responded in 1976 with a worded Open Letter to Hobbyists that accused the copiers of theft and declared that he could not continue developing computer software that people did not pay for. Many hobbyists reacted defensively to the letter.
Under the terms of the purchase agreement, MITS would receive the rights to the interpreter after it had paid a certain amount in royalties. However, Microsoft had developed versions of the interpreter for other systems such as the Motorola 6800; when they decided to leave MITS, a dispute arose over whether the full amount had been paid and whether the agreement applied to the other versions. Microsoft and MITS took the dispute to an arbitrator who, much to Roberts' surprise, decided in favor of Microsoft based on MITS failure to market the software with their "best efforts". BASIC interpreters remained the core of Microsoft's business until the early 1980s, when it shifted to MS-DOS. Microsoft Binary Format Freiberger, Paul. Fire in the Valley: The Making of the Personal Computer. New York, NY: McGraw Hill. ISBN 0-07-135892-7. Gates, Bill; the Road Ahead. New York: Viking. ISBN 0-670-77289-5. Cringely, Robert X.. Triumph of the Nerds. PBS, 1996. Bunnell, David. "Altair BASIC — Up and Running". Computer Notes.
Altair Users Group, MITS Inc. 1: 1, 3. Archived from the original on March 23, 2012. Retrieved 2007-04-18. Altair BASIC 3.2 - Annotated Disassembly Altair BASIC source disassembly, compiled by Reuben Harris and archived at archive.org Writing an Altair Basic, Interview with
Digital Equipment Corporation
Digital Equipment Corporation, using the trademark Digital, was a major American company in the computer industry from the 1950s to the 1990s. DEC was a leading vendor of computer systems, including computers and peripherals, their PDP and successor VAX products were the most successful of all minicomputers in terms of sales. DEC was acquired in June 1998 by Compaq, in what was at that time the largest merger in the history of the computer industry. At the time, Compaq was focused on the enterprise market and had purchased several other large vendors. DEC was a major player overseas. However, Compaq had little idea what to do with its acquisitions, soon found itself in financial difficulty of its own; the company subsequently merged with Hewlett-Packard in May 2002. As of 2007, PDP-11, VAX, AlphaServer systems were still produced under the HP name. From 1957 until 1992, DEC's headquarters were located in a former wool mill in Maynard, Massachusetts. DEC was acquired in June 1998 by Compaq, which subsequently merged with Hewlett-Packard in May 2002.
Some parts of DEC, notably the compiler business and the Hudson, Massachusetts facility, were sold to Intel. Focusing on the small end of the computer market allowed DEC to grow without its potential competitors making serious efforts to compete with them, their PDP series of machines became popular in the 1960s the PDP-8 considered to be the first successful minicomputer. Looking to simplify and update their line, DEC replaced most of their smaller machines with the PDP-11 in 1970 selling over 600,000 units and cementing DEC's position in the industry. Designed as a follow-on to the PDP-11, DEC's VAX-11 series was the first used 32-bit minicomputer, sometimes referred to as "superminis"; these systems were able to compete in many roles with larger mainframe computers, such as the IBM System/370. The VAX was a best-seller, with over 400,000 sold, its sales through the 1980s propelled the company into the second largest computer company in the industry. At its peak, DEC was the second largest employer in Massachusetts, second only to the Massachusetts State Government.
The rapid rise of the business microcomputer in the late 1980s, the introduction of powerful 32-bit systems in the 1990s eroded the value of DEC's systems. DEC's last major attempt to find a space in the changing market was the DEC Alpha 64-bit RISC instruction set architecture. DEC started work on Alpha as a way to re-implement their VAX series, but employed it in a range of high-performance workstations. Although the Alpha processor family met both of these goals, for most of its lifetime, was the fastest processor family on the market high asking prices were outsold by lower priced x86 chips from Intel and clones such as AMD. DEC was acquired in June 1998 by Compaq, in what was at that time the largest merger in the history of the computer industry. At the time, Compaq was focused on the enterprise market and had purchased several other large vendors. DEC was a major player overseas. However, Compaq had little idea what to do with its acquisitions, soon found itself in financial difficulty of its own.
The company subsequently merged with Hewlett-Packard in May 2002. As of 2007, some of DEC's product lines were still produced under the HP name. Beyond DECsystem-10/20, PDP, VAX and Alpha, DEC was well respected for its communication subsystem designs, such as Ethernet, DNA, DSA, its "dumb terminal" subsystems including VT100 and DECserver products. DEC's Research Laboratories conducted DEC's corporate research; some of them are still operated by Hewlett-Packard. The laboratories were: Western Research Laboratory in Palo Alto, California, US Systems Research Center in Palo Alto, California, US Network Systems Laboratory in Palo Alto, California, US Cambridge Research Laboratory in Cambridge, Massachusetts, US Paris Research Laboratory in Paris, France MetroWest Technology Campus in Maynard, Massachusetts, USSome of the former employees of DEC's Research Labs or DEC's R&D in general include: Gordon Bell: technical visionary, VP Engineering 1972–83. DEC supported the ANSI standards the ASCII character set, which survives in Unicode and the ISO 8859 character set family.
DEC's own Multinational Character Set had a large influence on ISO 8859-1 and, by extension, Unicode. The first versions of the C language and the Unix operating system ran on DEC's PDP series of computers, which were among the first commercially viable minicomputers, although for several years DEC itself did not encourage the use of Unix. DEC produced used and influential interactive ope
Transportation engineering or transport engineering is the application of technology and scientific principles to the planning, functional design and management of facilities for any mode of transportation in order to provide for the safe, rapid, convenient and environmentally compatible movement of people and goods transport. The planning aspects of transportation engineering relate to elements of urban planning, involve technical forecasting decisions and political factors. Technical forecasting of passenger travel involves an urban transportation planning model, requiring the estimation of trip generation, trip distribution, mode choice, route assignment. More sophisticated forecasting can include other aspects of traveler decisions, including auto ownership, trip chaining and the choice of residential or business location. Passenger trips are the focus of transportation engineering because they represent the peak of demand on any transportation system. A review of descriptions of the scope of various committees indicates that while facility planning and design continue to be the core of the transportation engineering field, such areas as operations planning, network analysis and policy analysis are important to those working in highway and urban transportation.
The National Council of Examiners for Engineering and Surveying list online the safety protocols, geometric design requirements, signal timing. Transportation engineering involves planning, construction and operation of transportation facilities; the facilities support air, railroad, pipeline and space transportation. The design aspects of transportation engineering include the sizing of transportation facilities, determining the materials and thickness used in pavement designing the geometry of the roadway. Before any planning occurs an engineer must take what is known as an inventory of the area or, if it is appropriate, the previous system in place; this inventory or database must include information on population, land use, economic activity, transportation facilities and services, travel patterns and volumes and ordinances, regional financial resources, community values and expectations. These inventories help the engineer create business models to complete accurate forecasts of the future conditions of the system.
Operations and management involve traffic engineering, so that vehicles move smoothly on the road or track. Older techniques include signs, signals and tolling. Newer technologies involve intelligent transportation systems, including advanced traveler information systems, advanced traffic control systems, vehicle infrastructure integration. Human factors are an aspect of transportation engineering concerning driver-vehicle interface and user interface of road signs and markings. Engineers in this specialization: Handle the planning, design and operation of highways and other vehicular facilities as well as their related bicycle and pedestrian realms Estimate the transportation needs of the public and secure the funding for projects Analyze locations of high traffic volumes and high collisions for safety and capacity Use engineering principles to improve the transportation system Utilize the three design controls, which are the drivers, the vehicles, the roadways themselves Railway engineers handle the design and operation of railroads and mass transit systems that use a fixed guideway.
Typical tasks include determining horizontal and vertical alignment design, station location and design, construction cost estimating. Railroad engineers can move into the specialized field of train dispatching which focuses on train movement control. Railway engineers work to build a cleaner and safer transportation network by reinvesting and revitalizing the rail system to meet future demands. In the United States, railway engineers work with elected officials in Washington, D. C. on rail transportation issues to make sure that the rail system meets the country's transportation needs. Port and harbor engineers handle the design and operation of ports, harbors and other maritime facilities. Airport engineers construct airports. Airport engineers must account for the impacts and demands of aircraft in their design of airport facilities; these engineers must use the analysis of predominant wind direction to determine runway orientation, determine the size of runway border and safety areas, different wing tip to wing tip clearances for all gates and must designate the clear zones in the entire port.
Media related to Transport engineering at Wikimedia Commons http://www.ite.org Institute of Transportation Engineers, a professional society for transportation engineers http://www.itsa.org ITS America http://www.asce.org ASCE
Seattle is a seaport city on the West Coast of the United States. It is the seat of Washington. With an estimated 730,000 residents as of 2018, Seattle is the largest city in both the state of Washington and the Pacific Northwest region of North America. According to U. S. Census data released in 2018, the Seattle metropolitan area’s population stands at 3.87 million, ranks as the 15th largest in the United States. In July 2013, it was the fastest-growing major city in the United States and remained in the Top 5 in May 2015 with an annual growth rate of 2.1%. In July 2016, Seattle was again the fastest-growing major U. S. city, with a 3.1% annual growth rate. Seattle is the northernmost large city in the United States; the city is situated on an isthmus between Puget Sound and Lake Washington, about 100 miles south of the Canada–United States border. A major gateway for trade with Asia, Seattle is the fourth-largest port in North America in terms of container handling as of 2015; the Seattle area was inhabited by Native Americans for at least 4,000 years before the first permanent European settlers.
Arthur A. Denny and his group of travelers, subsequently known as the Denny Party, arrived from Illinois via Portland, Oregon, on the schooner Exact at Alki Point on November 13, 1851; the settlement was moved to the eastern shore of Elliott Bay and named "Seattle" in 1852, in honor of Chief Si'ahl of the local Duwamish and Suquamish tribes. Today, Seattle has high populations of Native, Scandinavian and Asian Americans, as well as a thriving LGBT community that ranks 6th in the United States for population. Logging was Seattle's first major industry, but by the late 19th century, the city had become a commercial and shipbuilding center as a gateway to Alaska during the Klondike Gold Rush. Growth after World War II was due to the local Boeing company, which established Seattle as a center for aircraft manufacturing; the Seattle area developed into a technology center from the 1980s onwards with companies like Microsoft becoming established in the region. Internet retailer Amazon was founded in Seattle in 1994, major airline Alaska Airlines is based in SeaTac, serving Seattle's international airport, Seattle–Tacoma International Airport.
The stream of new software and Internet companies led to an economic revival, which increased the city's population by 50,000 between 1990 and 2000. Owing to its increasing population in the 21st century and the state of Washington have some of the highest minimum wages in the country, at $15 per hour for smaller businesses and $16 for the city's largest employers. Seattle has a noteworthy musical history. From 1918 to 1951, nearly two dozen jazz nightclubs existed along Jackson Street, from the current Chinatown/International District to the Central District; the jazz scene nurtured the early careers of Ray Charles, Quincy Jones, Ernestine Anderson, others. Seattle is the birthplace of rock musician Jimi Hendrix, as well as the origin of the bands Nirvana, Pearl Jam, Alice in Chains, Foo Fighters and the alternative rock movement grunge. Archaeological excavations suggest that Native Americans have inhabited the Seattle area for at least 4,000 years. By the time the first European settlers arrived, the people occupied at least seventeen villages in the areas around Elliott Bay.
The first European to visit the Seattle area was George Vancouver, in May 1792 during his 1791–95 expedition to chart the Pacific Northwest. In 1851, a large party led by Luther Collins made a location on land at the mouth of the Duwamish River. Thirteen days members of the Collins Party on the way to their claim passed three scouts of the Denny Party. Members of the Denny Party claimed land on Alki Point on September 28, 1851; the rest of the Denny Party set sail from Portland and landed on Alki point during a rainstorm on November 13, 1851. After a difficult winter, most of the Denny Party relocated across Elliott Bay and claimed land a second time at the site of present-day Pioneer Square, naming this new settlement Duwamps. Charles Terry and John Low remained at the original landing location and reestablished their old land claim and called it "New York", but renamed "New York Alki" in April 1853, from a Chinook word meaning "by and by" or "someday". For the next few years, New York Alki and Duwamps competed for dominance, but in time Alki was abandoned and its residents moved across the bay to join the rest of the settlers.
David Swinson "Doc" Maynard, one of the founders of Duwamps, was the primary advocate to name the settlement after Chief Seattle of the Duwamish and Suquamish tribes. The name "Seattle" appears on official Washington Territory papers dated May 23, 1853, when the first plats for the village were filed. In 1855, nominal land settlements were established. On January 14, 1865, the Legislature of Territorial Washington incorporated the Town of Seattle with a board of trustees managing the city; the Town of Seattle was disincorporated on January 18, 1867, remained a mere precinct of King County until late 1869, when a new petition was filed and the city was re-incorporated December 2, 1869, with a mayor–council government. The corporate seal of the City of Seattle carries the date "1869" and a likeness of Chief Sealth in left profile. Seattle has a history of boom-and-bust cycles, like many other cities near areas of extensive natural and mineral resources. Seattle has risen several times economically gone into precipitous decline, but it has used those periods to rebuild solid infrastructure
CP/M standing for Control Program/Monitor and Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/85-based microcomputers by Gary Kildall of Digital Research, Inc. Confined to single-tasking on 8-bit processors and no more than 64 kilobytes of memory 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, an early standard in the microcomputer industry. This computer platform was used in business through the late 1970s and into the mid-1980s. CP/M increased the market size for both hardware and software by reducing the amount of programming required to install an application on a new manufacturer's computer. An important driver of software innovation was the advent of low-cost microcomputers running CP/M, as independent programmers and hackers bought them and shared their creations in user groups. CP/M was displaced by DOS soon after the 1981 introduction of the IBM PC.
A minimal 8-bit CP/M system would contain the following components: A computer terminal using the ASCII character set An Intel 8080 or Zilog Z80 microprocessor The NEC V20 and V30 processors support an 8080-emulation mode that can run 8-bit CP/M on a PC DOS/MS-DOS computer so equipped, though any PC can run the 16-bit CP/M-86. At least 16 kilobytes of RAM, beginning at address 0 A means to bootstrap the first sector of the diskette At least one floppy disk driveThe only hardware system that CP/M, as sold by Digital Research, would support was the Intel 8080 Development System. Manufacturers of CP/M-compatible systems customized portions of the operating system for their own combination of installed memory, disk drives, console devices. CP/M would run on systems based on the Zilog Z80 processor since the Z80 was compatible with 8080 code. While the Digital Research distributed core of CP/M did not use any of the Z80-specific instructions, many Z80-based systems used Z80 code in the system-specific BIOS, many applications were dedicated to Z80-based CP/M machines.
On most machines the bootstrap was a minimal bootloader in ROM combined with some means of minimal bank switching or a means of injecting code on the bus. 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, Osborne machines used the 8th bit set to indicate an underlined character. WordStar used the 8th bit as an end-of-word marker. International CP/M systems most used the ISO 646 norm for localized character sets, replacing certain ASCII characters with localized characters rather than adding them beyond the 7-bit boundary. In the 8-bit versions, while running, the CP/M operating system loaded into memory had three components: Basic Input/Output System or BIOS, Basic Disk Operating System or BDOS, Console Command Processor or CCP; the BIOS and BDOS were memory-resident, while the CCP was memory-resident unless overwritten by an application, in which case it was automatically reloaded after the application finished running.
A number of transient commands for standard utilities were provided. The transient commands resided in files with the extension. COM on disk; the BIOS directly controlled hardware components other than main memory. It contained functions such as character 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 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 operating 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 operating system from the disk in drive A:. By modern standards CP/M was primitive. 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 disk's directory information, ruining the data stored on the disk. From version 1.1 or 1.2 onwards, changing a disk trying to write to it before its directory was read would cause a fatal error to be signalled. This avoided overwriting the disk but required a reboot and loss of the data, to be stored on disk; the majority of the complexity in CP/M was isolated in the BDOS, to a lesser extent, the CCP and transient commands. This meant that by porting the limited number of simple routines in the BIOS to a particular hardware platform, the entire OS would work.