1.
NeXT
–
NeXT was founded by Jobs after he was ousted at Apple, along with several co-workers. NeXT introduced the first NeXT Computer in 1988, and the smaller NeXTstation in 1990, the NeXT computers experienced relatively limited sales, with estimates of about 50,000 units shipped in total. Nevertheless, their innovative object-oriented NeXTSTEP operating system and development environment were highly influential, NeXT later released much of the NeXTSTEP system as a programming environment standard called OpenStep. NeXT withdrew from the business in 1993 to concentrate on marketing OPENSTEP for Mach, its own OpenStep implementation. NeXT also developed WebObjects, one of the first enterprise Web application frameworks, Apple purchased NeXT in 1997 for $429 million, and 1.5 million shares of Apple stock. As part of the agreement, Steve Jobs, Chairman and CEO of NeXT Software, returned to Apple, the founder promised to merge software from NeXT with Apples hardware platforms, eventually resulting in macOS, iOS, watchOS and tvOS. Parts of these systems incorporated the OPENSTEP foundation. In 1985, Apple co-founder Steve Jobs led Apples SuperMicro division, the Macintosh had been successful on university campuses partly because of the Apple University Consortium, which allowed students and institutions to buy the computers at a discount. The consortium had earned more than $50 million on computers by February 1984, while chairman, Jobs visited university departments and faculty members to sell Macintosh. Jobs met Paul Berg, a Nobel Laureate in chemistry, at a luncheon held in Silicon Valley to honor François Mitterrand, wet labs were prohibitively expensive for lower-level courses and were too complex to be simulated on personal computers of the time. Jobs was intrigued by Bergs concept of a workstation and contemplated starting a higher education company in the fall of 1985. Jobs division did not release upgraded versions of the Macintosh and most of the Macintosh Office, as a result, sales plummeted, and Apple was forced to write off millions of dollars in unsold inventory. Apples chief executive officer John Sculley ousted Jobs from his role at Apple. Later that year, Jobs began a struggle to regain control of the company. The board of directors sided with Sculley while Jobs took a visit to Western Europe. After several months of being sidelined, Jobs resigned from Apple on September 13,1985 and he told the board he was leaving to set up a new computer company, and that he would be taking several Apple employees from the SuperMicro division with him. He also told the board that his new company would not compete with Apple, Jobs named his new company Next, Inc. A number of former Apple employees followed him to Next, including Joanna Hoffman, Bud Tribble, George Crow, Rich Page, Susan Barnes, Susan Kare, and Danl Lewin
NeXT
–
This original NeXT Computer was used by
Tim Berners-Lee at
CERN, and became the world's first
web server and ran the
world's first web browser in 1990
NeXT
–
The NeXT logo designed by
Paul Rand
NeXT
–
A
NeXTstation with the original keyboard, mouse and the
NeXT MegaPixel monitor
NeXT
–
Career
2.
Fremont, California
–
Fremont is a city in Alameda County, California, United States. It was incorporated on January 23,1956, from the merger of five communities, Centerville, Niles, Irvington, Mission San Jose. The city is named after American explorer John Charles Frémont, located in the southeast section of the San Francisco Bay Area in the East Bay region primarily, Fremont has a population of around 230,000. It is the fourth most populous city in the San Francisco Bay Area, and it is the closest East Bay city to Silicon Valley, and is thus sometimes associated with it. The area consisting of Fremont, Newark, and Union City, is now known as the Tri-City Area, Fremont is home to the largest population of Afghan Americans in the United States. The recorded history of the Fremont area began on June 6,1795, the Mission was established at the site of the Ohlone village of Oroysom. On their second day in the area, the Mission party killed a bear in Niles Canyon. The first English-speaking visitor to Fremont was the renowned trapper and explorer Jedediah Smith in 1827, the Mission prospered, eventually reaching a population of 1,887 inhabitants in 1831. The influence of the missionaries declined after 1834, when the Mexican government enacted secularization, José de Jesus Vallejo, brother of Mariano Vallejo, was the grantee of the Rancho Arroyo de la Alameda Mexican land grant. His family was influential in the Fremont area in the colonial era. In 1846 they were visited by the towns namesake John C, Frémont, who mapped a trail through Mission Pass to provide access for American settlers into the southeastern San Francisco Bay Area. The Fremont area grew rapidly at the time of the California Gold Rush, a town called Mission San Jose grew up around the old mission, with its own post office from 1850. Agriculture dominated the economy with grapes, nursery plants and olives as leading crops, in 1868 the 6. 8-magnitude Hayward earthquake on the Hayward Fault collapsed buildings throughout the Fremont area, ruining Mission San José and its outbuildings. Until the 1906 San Francisco earthquake caused its destruction, the Fremont areas Palmdale Winery was the largest in California, the ruins of the Palmdale Winery are still visible near the Five Corners in Irvington. From 1912 to 1915 the Niles section of the Fremont area was the earliest home of Californias motion picture industry, Charlie Chaplin filmed several movies in the Fremont area, most notably The Tramp. Fremont was incorporated under the leadership of Wally Pond in 1956, when the Glenmoor Gardens Homeowners Association was incorporated, in March 1953, there were no more than 75 houses in the subdivision. It was probably the first such organization in the Fremont area, in its scope, the five-member board of directors was set up to oversee a full range of services, from police and fire protection to street maintenance. Fremont became more industrialized between 1953 and 1962, a boom in high-tech employment in the 1980s to the late 1990s, especially in the Warm Springs District, caused rapid development in the city and linked the city with the Silicon Valley
Fremont, California
–
A view of Mission Peak from
Fremont Central Park
Fremont, California
–
Niles Art Walk 2005.
Fremont, California
–
The main facade of the restored 1809 Mission San José chapel
Fremont, California
–
Lake Elizabeth of Fremont Central Park
3.
Workstation
–
A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are connected to a local area network. Workstations offered higher performance than mainstream personal computers, especially with respect to CPU and graphics, memory capacity, and multitasking capability. Typically, the factor is that of a desktop computer, consist of a high resolution display, a keyboard and a mouse at a minimum. Workstations were the first segment of the market to present advanced accessories. The increasing capabilities of mainstream PCs in the late 1990s have blurred the lines somewhat with technical/scientific workstations, perhaps the first computer that might qualify as a workstation was the IBM1620, a small scientific computer designed to be used interactively by a single person sitting at the console. One peculiar feature of the machine was that it lacked any actual arithmetic circuitry, to perform addition, it required a memory-resident table of decimal addition rules. This saved on the cost of logic circuitry, enabling IBM to make it inexpensive, the machine was code-named CADET and rented initially for $1000 a month. In 1965, IBM introduced the IBM1130 scientific computer, which was meant as the successor to the 1620, both of these systems came with the ability to run programs written in Fortran and other languages. Both the 1620 and the 1130 were built into roughly desk-sized cabinets, both were available with add-on disk drives, printers, and both paper-tape and punched-card I/O. A console typewriter for direct interaction was standard on each, early examples of workstations were generally dedicated minicomputers, a system designed to support a number of users would instead be reserved exclusively for one person. A notable example was the PDP-8 from Digital Equipment Corporation, regarded to be the first commercial minicomputer, Lisp Machines were commercialized beginning 1980 by companies like Symbolics, Lisp Machines, Texas Instruments and Xerox. The first computer designed for single-users, with high-resolution graphics facilities was the Xerox Alto developed at Xerox PARC in 1973, other early workstations include the Terak 8510/a, Three Rivers PERQ and the later Xerox Star. Meanwhile, DARPAs VLSI Project created several spinoff graphics products as well, notably the SGI3130 and it was not uncommon to differentiate the target market for the products, with Sun and Apollo considered to be network workstations, while the SGI machines were graphics workstations. As RISC microprocessors became available in the mid-1980s, these were adopted by many workstation vendors, workstations tended to be very expensive, typically several times the cost of a standard PC and sometimes costing as much as a new car. However, minicomputers sometimes cost as much as a house, additionally, workstations, given their more specialized nature, tend to have higher profit margins than commodity-driven PCs. Additionally, the companies that make the products tend to have very good repair/replacement plans, some low-cost workstations are still expensive by PC standards, but offer binary compatibility with higher-end workstations and servers made by the same vendor. This allows software development to take place on low-cost desktop machines, Graphics workstations often shipped with graphics accelerators
Workstation
–
Sun SPARCstation 10 with
CRT monitor, from the early 1990s
Workstation
–
Early
Xerox workstation
Workstation
–
HP 9000 model 425 workstation running
HP-UX 9 and
Visual User Environment (VUE)
Workstation
–
NeXTstation graphics workstation from 1990
4.
United States dollar
–
The United States dollar is the official currency of the United States and its insular territories per the United States Constitution. It is divided into 100 smaller cent units, the circulating paper money consists of Federal Reserve Notes that are denominated in United States dollars. The U. S. dollar was originally commodity money of silver as enacted by the Coinage Act of 1792 which determined the dollar to be 371 4/16 grain pure or 416 grain standard silver, the currency most used in international transactions, it is the worlds primary reserve currency. Several countries use it as their currency, and in many others it is the de facto currency. Besides the United States, it is used as the sole currency in two British Overseas Territories in the Caribbean, the British Virgin Islands and Turks and Caicos Islands. A few countries use the Federal Reserve Notes for paper money, while the country mints its own coins, or also accepts U. S. coins that can be used as payment in U. S. dollars. After Nixon shock of 1971, USD became fiat currency, Article I, Section 8 of the U. S. Constitution provides that the Congress has the power To coin money, laws implementing this power are currently codified at 31 U. S. C. Section 5112 prescribes the forms in which the United States dollars should be issued and these coins are both designated in Section 5112 as legal tender in payment of debts. The Sacagawea dollar is one example of the copper alloy dollar, the pure silver dollar is known as the American Silver Eagle. Section 5112 also provides for the minting and issuance of other coins and these other coins are more fully described in Coins of the United States dollar. The Constitution provides that a regular Statement and Account of the Receipts and that provision of the Constitution is made specific by Section 331 of Title 31 of the United States Code. The sums of money reported in the Statements are currently being expressed in U. S. dollars, the U. S. dollar may therefore be described as the unit of account of the United States. The word dollar is one of the words in the first paragraph of Section 9 of Article I of the Constitution, there, dollars is a reference to the Spanish milled dollar, a coin that had a monetary value of 8 Spanish units of currency, or reales. In 1792 the U. S. Congress passed a Coinage Act, Section 20 of the act provided, That the money of account of the United States shall be expressed in dollars, or units. And that all accounts in the offices and all proceedings in the courts of the United States shall be kept and had in conformity to this regulation. In other words, this act designated the United States dollar as the unit of currency of the United States, unlike the Spanish milled dollar the U. S. dollar is based upon a decimal system of values. Both one-dollar coins and notes are produced today, although the form is significantly more common
United States dollar
–
Series of 1917
$1 United States bill
United States dollar
–
Federal Reserve Notes
United States dollar
–
Spanish silver real or
peso of 1768
United States dollar
–
Obverse of rare 1934 $500 Federal Reserve Note, featuring a portrait of President
William McKinley.
5.
Operating system
–
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
Operating system
–
OS/360 was used on most IBM mainframe computers beginning in 1966, including computers used by the
Apollo program.
Operating system
Operating system
–
The
first server for the
World Wide Web ran on NeXTSTEP, based on BSD
6.
NeXTSTEP
–
NeXTSTEP is a discontinued object-oriented, multitasking operating system based on UNIX. Although relatively unsuccessful at the time, it attracted interest from computer scientists and it was also the platform on which Tim Berners-Lee created the first web browser. After the purchase of NeXT by Apple, it became the source of the operating systems macOS, iOS, watchOS and tvOS. Many bundled macOS applications, such as TextEdit, Mail and Chess, are descendants of NeXTSTEP applications, the toolkits offer considerable power, and are the canonical development system for all of the software on the machine. NeXTSTEPs user interface is considered to be refined and consistent and it introduced the idea of the Dock and the Shelf. Additional kits were added to the line to make the system more attractive. These include Portable Distributed Objects, which allow easy remote invocation, and Enterprise Objects Framework, the kits made the system particularly interesting to custom application programmers, and NeXTSTEP had a long history in the financial programming community. A preview release of NeXTSTEP was shown with the launch of the NeXT Computer on October 12,1988, the first full release, NeXTSTEP1.0, shipped on September 18,1989. NeXTSTEP was later modified to separate the underlying operating system from the higher-level object libraries, the result was the OpenStep API, which ran on multiple underlying operating systems, including NeXTs own OPENSTEP, Windows NT and SUN Solaris. NeXTSTEPs legacy stands today in the form of its direct descendents, from day one, the operating system of NeXTSTEP was built upon Mach/BSD. It was built on 4. 3BSD Tahoe and it changed to 4. 3BSD Reno after the release of NeXTSTEP3.0. It changed to 4. 4BSD during the development of Rhapsody, the first web browser, WorldWideWeb, and the first ever app store were all invented on the NeXTSTEP platform. Some features and keyboard shortcuts now commonly found in web browsers can be traced back to NeXTSTEP conventions, the basic layout options of HTML1.0 and 2.0 are attributable to those features available in NeXTs Text class. Other games based on the Doom engine such as Heretic and its sequel Hexen by Raven Software as well as Strife by Rogue Entertainment were also developed on NeXT hardware using ids tools. Altsys made a NeXTSTEP application called Virtuoso, version 2 of which was ported to Mac OS, the modern Notebook interface for Mathematica, and the advanced spreadsheet Lotus Improv, were developed using NeXTSTEP. The software that controlled MCIs Friends and Family calling plan program was developed using NeXTSTEP, about the time of the release of NeXTSTEP3.2, NeXT partnered with Sun Microsystems to develop OpenStep. It is the product of an effort to separate the underlying operating system from the higher-level object libraries to create a cross-platform object-oriented API standard derived from NeXTSTEP, the OpenStep API targets multiple underlying operating systems, including NeXTs own OPENSTEP. Implementations of that standard were released for Suns Solaris, Windows NT, NeXTs implementation is called OPENSTEP for Mach and its first release superseded NeXTSTEP3.3 on NeXT, Sun and Intel IA-32 systems
NeXTSTEP
–
NeXTSTEP
graphical user interface
7.
Central processing unit
–
The computer industry has used the term central processing unit at least since the early 1960s. The form, design and implementation of CPUs have changed over the course of their history, most modern CPUs are microprocessors, meaning they are contained on a single integrated circuit chip. An IC that contains a CPU may also contain memory, peripheral interfaces, some computers employ a multi-core processor, which is a single chip containing two or more CPUs called cores, in that context, one can speak of such single chips as sockets. Array processors or vector processors have multiple processors that operate in parallel, there also exists the concept of virtual CPUs which are an abstraction of dynamical aggregated computational resources. Early computers such as the ENIAC had to be rewired to perform different tasks. Since the term CPU is generally defined as a device for software execution, the idea of a stored-program computer was already present in the design of J. Presper Eckert and John William Mauchlys ENIAC, but was initially omitted so that it could be finished sooner. On June 30,1945, before ENIAC was made, mathematician John von Neumann distributed the paper entitled First Draft of a Report on the EDVAC and it was the outline of a stored-program computer that would eventually be completed in August 1949. EDVAC was designed to perform a number of instructions of various types. Significantly, the programs written for EDVAC were to be stored in high-speed computer memory rather than specified by the wiring of the computer. This overcame a severe limitation of ENIAC, which was the considerable time, with von Neumanns design, the program that EDVAC ran could be changed simply by changing the contents of the memory. Early CPUs were custom designs used as part of a larger, however, this method of designing custom CPUs for a particular application has largely given way to the development of multi-purpose processors produced in large quantities. This standardization began in the era of discrete transistor mainframes and minicomputers and has accelerated with the popularization of the integrated circuit. The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers, both the miniaturization and standardization of CPUs have increased the presence of digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in electronic devices ranging from automobiles to cellphones, the so-called Harvard architecture of the Harvard Mark I, which was completed before EDVAC, also utilized a stored-program design using punched paper tape rather than electronic memory. Relays and vacuum tubes were used as switching elements, a useful computer requires thousands or tens of thousands of switching devices. The overall speed of a system is dependent on the speed of the switches, tube computers like EDVAC tended to average eight hours between failures, whereas relay computers like the Harvard Mark I failed very rarely. In the end, tube-based CPUs became dominant because the significant speed advantages afforded generally outweighed the reliability problems, most of these early synchronous CPUs ran at low clock rates compared to modern microelectronic designs. Clock signal frequencies ranging from 100 kHz to 4 MHz were very common at this time, the design complexity of CPUs increased as various technologies facilitated building smaller and more reliable electronic devices
Central processing unit
–
An
Intel 80486DX2 CPU, as seen from above
Central processing unit
–
Bottom side of an Intel 80486DX2
Central processing unit
–
EDVAC, one of the first stored-program computers
Central processing unit
–
CPU,
core memory, and
external bus interface of a DEC
PDP-8 /I. Made of medium-scale integrated circuits.
8.
Motorola 68030
–
The Motorola 68030 is a 32-bit microprocessor in Motorolas 68000 family. The 68030 was the successor to the Motorola 68020, and was followed by the Motorola 68040, in keeping with general Motorola naming, this CPU is often referred to as the 030. The 68030 features 273,000 transistors with on-chip instruction and data caches of 256 bytes each and it also has an on-chip MMU but does not have a built in floating-point unit. The 68881 and the faster 68882 floating point unit chips could be used with the 68030, a lower cost version of the 68030, the Motorola 68EC030, was also released, lacking the on-chip MMU. It was commonly available in both 132 pin QFP and 128 pin PGA packages, the poorer thermal characteristics of the QFP package limited the full 68030 QFP variant to 33 MHz. The PGA 68030s included 40 MHz and 50 MHz versions, there was also a small supply of QFP packaged EC variants. Motorola used the process shrink to pack more hardware on the die, in case it was the MMU. The integration of the MMU made it more cost-effective than the 68020 with an external MMU, however, the 68030 can switch between synchronous and asynchronous buses without a reset. The 68030 also lacks some of the 68020s instructions but it lowers power draw by ~25%, when used with a 68020 bus, the 68030 did not differentiate itself in performance from the 68020 that it was derived from. However, the 68030 provides a synchronous bus interface which, if used. The finer manufacturing process allowed Motorola to scale the full-version processor to 50 MHz, the EC variety topped out at 40 MHz. It was also used in Unix workstations such as the Sun Microsystems Sun 3/80 desktop workstation, Laser printers, more recently, the 68030 core has also been adapted by Freescale into a microcontroller for embedded applications. The 68EC030 is a low cost version of the 68030, the difference between the two being that the 68EC030 does not have a memory management unit. The 68EC030 was used as the CPU of the Amiga 3000, one model of the Amiga 4000, and in the Cisco Systems 2500 Series router, a small-to-medium enterprise computer internetworking appliance. The 50 MHz speed is exclusive to the ceramic PGA package and this article is based on material taken from the Free On-line Dictionary of Computing prior to 1 November 2008 and incorporated under the relicensing terms of the GFDL, version 1.3 or later. 68030 images and descriptions at cpu-collection. de Official information about the Freescale MC68030 microcontroller
Motorola 68030
–
Motorola 68030 microprocessor
Motorola 68030
–
Motorola MC68030RC33B Die Image
9.
MHz
–
The hertz is the unit of frequency in the International System of Units and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide proof of the existence of electromagnetic waves. Hertz are commonly expressed in SI multiples kilohertz, megahertz, gigahertz, kilo means thousand, mega meaning million, giga meaning billion and tera for trillion. Some of the units most common uses are in the description of waves and musical tones, particularly those used in radio-. It is also used to describe the speeds at which computers, the hertz is equivalent to cycles per second, i. e. 1/second or s −1. In English, hertz is also used as the plural form, as an SI unit, Hz can be prefixed, commonly used multiples are kHz, MHz, GHz and THz. One hertz simply means one cycle per second,100 Hz means one hundred cycles per second, and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, the rate of aperiodic or stochastic events occur is expressed in reciprocal second or inverse second in general or, the specific case of radioactive decay, becquerels. Whereas 1 Hz is 1 cycle per second,1 Bq is 1 aperiodic radionuclide event per second, the conversion between a frequency f measured in hertz and an angular velocity ω measured in radians per second is ω =2 π f and f = ω2 π. This SI unit is named after Heinrich Hertz, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, the hertz is named after the German physicist Heinrich Hertz, who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission in 1930, the term cycles per second was largely replaced by hertz by the 1970s. One hobby magazine, Electronics Illustrated, declared their intention to stick with the traditional kc. Mc. etc. units, sound is a traveling longitudinal wave which is an oscillation of pressure. Humans perceive frequency of waves as pitch. Each musical note corresponds to a frequency which can be measured in hertz. An infants ear is able to perceive frequencies ranging from 20 Hz to 20,000 Hz, the range of ultrasound, infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtoHz into the terahertz range and beyond. Electromagnetic radiation is described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation is measured in kilohertz, megahertz, or gigahertz
MHz
–
Details of a
heartbeat as an example of a non-
sinusoidal periodic phenomenon that can be described in terms of hertz. Two complete cycles are illustrated.
MHz
–
A
sine wave with varying frequency
10.
Floating point unit
–
A floating-point unit is a part of a computer system specially designed to carry out operations on floating point numbers. Typical operations are addition, subtraction, multiplication, division, square root, some systems can also perform various transcendental functions such as exponential or trigonometric calculations, though in most modern processors these are done with software library routines. This could be an integrated circuit, an entire circuit board or a cabinet. Where floating-point calculation hardware has not been provided, floating point calculations are done in software, emulation can be implemented on any of several levels, in the CPU as microcode, as an operating system function, or in user space code. When only integer functionality is available the CORDIC floating point emulation methods are most commonly used, in most modern computer architectures, there is some division of floating-point operations from integer operations. This division varies significantly by architecture, some, like the Intel x86 have dedicated floating-point registers, in earlier superscalar architectures without general out-of-order execution, floating-point operations were sometimes pipelined separately from integer operations. Since the early 1990s, many microprocessors for desktops and servers have more than one FPU, the modular architecture of Bulldozer microarchitecture uses a special FPU named FlexFPU, which uses simultaneous multithreading. Each physical integer core, two per module, is threaded, in contrast with Intels Hyperthreading, where two virtual simultaneous threads share the resources of a single physical core. Some floating-point hardware only supports the simplest operations - addition, subtraction, but even the most complex floating-point hardware has a finite number of operations it can support - for example, none of them directly support arbitrary-precision arithmetic. When a CPU is executing a program calls for a floating-point operation that is not directly supported by the hardware. In systems without any floating-point hardware, the CPU emulates it using a series of simpler fixed-point arithmetic operations that run on the arithmetic logic unit. The software that lists the series of operations to emulate floating-point operations is often packaged in a floating-point library. In some cases, FPUs may be specialized, and divided between simpler floating-point operations and more complicated operations, like division, in some cases, only the simple operations may be implemented in hardware or microcode, while the more complex operations are implemented as software. In the 1980s, it was common in IBM PC/compatible microcomputers for the FPU to be separate from the CPU. It would only be purchased if needed to speed up or enable math-intensive programs, the IBM PC, XT, and most compatibles based on the 8088 or 8086 had a socket for the optional 8087 coprocessor. Other companies manufactured co-processors for the Intel x86 series, coprocessors were available for the Motorola 68000 family, the 68881 and 68882. These were common in Motorola 68020/68030-based workstations like the Sun 3 series, there are also add-on FPUs coprocessor units for microcontroller units /single-board computer, which serve to provide floating-point arithmetic capability. These add-on FPUs are host-processor-independent, possess their own programming requirements and are provided with their own integrated development environments
Floating point unit
–
An Intel 80287
11.
Motorola 56000
–
The Motorola DSP56000 is a family of digital signal processor chips produced by Motorola Semiconductor starting in 1986 and is still being produced in more advanced models in the 2010s. The 56k series was popular for a time in a number of computers, including the NeXT, Atari Falcon. Upgraded 56k versions are used today in audio gear, radars, communications devices. The 56000 was also used as the basis for the updated 96000, the DSP56000 uses fixed-point arithmetic, with 24-bit program words and 24-bit data words. It includes two 24-bit registers, which can also be referred to as a single 48-bit register and it also includes two 56-bit accumulators, each with an 8-bit extension, otherwise, the accumulators are similar to the other 24/48-bit registers. Being a Modified Harvard architecture processor, the 56k has three memory spaces+buses, a program memory space/bus and two data memory space/bus. 24 bits were selected as the word length because it gave the system a reasonable number range and precision for processing audio. 24 bits correspond to a large 144 dB dynamic range, sufficient in the 1980s when analog-to-digital converters, one example is ADSL applications, where filters typically require 20 bits of accuracy. The leftmost four bits are considered ample headroom for calculations, the processor is capable of carrying out 16.5 Million Instructions Per Second at the maximum specified clock speed of 33 MHz. and has hardware support for block-floating point FFT. It uses 5 V TTL levels and consumes approximately 0.4 W, in most designs the 56000 is dedicated to one single task, because digital signal processing using special hardware is mostly real-time and does not allow any interruption. For somewhat more mildly demanding tasks which are not time-critical, or more of a simple if-then type, to this end the 56800 series added a complete MCU which created a single-chip DSPcontroller solution, while the opposite occurred in the 68456—a 68000 with a 56000 on it. Core clock frequencies ranged up to 250 MHz, freescale Digital Signal Processors A56 freeware assembler for the 56000 architecture dev-docs. atariforge. org - Atari documentation archive Product-Longevity Program
Motorola 56000
–
Motorola XSP56001
12.
Digital signal processor
–
A digital signal processor is a specialized microprocessor, with its architecture optimized for the operational needs of digital signal processing. The goal of DSPs is usually to measure, filter or compress continuous real-world analog signals, DSPs often use special memory architectures that are able to fetch multiple data or instructions at the same time. Digital signal processing algorithms typically require a number of mathematical operations to be performed quickly and repeatedly on a series of data samples. Signals are constantly converted from analog to digital, manipulated digitally, many DSP applications have constraints on latency, that is, for the system to work, the DSP operation must be completed within some fixed time, and deferred processing is not viable. A specialized digital signal processor, however, will tend to provide a lower-cost solution, with performance, lower latency. For example, the SES-12 and SES-14 satellites from operator SES, the architecture of a digital signal processor is optimized specifically for digital signal processing. Most also support some of the features as a processor or microcontroller. Some useful features for optimizing DSP algorithms are outlined below, sometimes various sticky bits operation modes are available. DSPs can sometimes rely on supporting code to know about cache hierarchies and this is a tradeoff that allows for better performance. In addition, extensive use of DMA is employed, DSPs frequently use multi-tasking operating systems, but have no support for virtual memory or memory protection. Operating systems that use virtual memory require more time for context switching among processes, the AMD2901 bit-slice chip with its family of components was a very popular choice. There were reference designs from AMD, but very often the specifics of a design were application specific. These bit slice architectures would sometimes include a peripheral multiplier chip, examples of these multipliers were a series from TRW including the TDC1008 and TDC1010, some of which included an accumulator, providing the requisite multiply–accumulate function. In 1976, Richard Wiggins proposed the Speak & Spell concept to Paul Breedlove, Larry Brantingham, two years later in 1978 they produced the first Speak & Spell, with the technological centerpiece being the TMS5100, the industrys first digital signal processor. It also set other milestones, being the first chip to use Linear predictive coding to perform speech synthesis, in 1978, Intel released the 2920 as an analog signal processor. It had an on-chip ADC/DAC with a signal processor. In 1979, AMI released the S2811 and it was designed as a microprocessor peripheral, and it had to be initialized by the host. The S2811 was likewise not successful in the market, in 1980 the first stand-alone, complete DSPs – the NEC µPD7720 and AT&T DSP1 – were presented at the International Solid-State Circuits Conference 80
Digital signal processor
–
A digital signal processor chip found in a
guitar effects unit
13.
Megabyte
–
The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB, but sometimes MByte is used, the unit prefix mega is a multiplier of 1000000 in the International System of Units. Therefore, one megabyte is one million bytes of information and this definition has been incorporated into the International System of Quantities. However, in the computer and information fields, several other definitions are used that arose for historical reasons of convenience. A common usage has been to one megabyte as 1048576bytes. However, most standards bodies have deprecated this usage in favor of a set of binary prefixes, less common is a convention that used the megabyte to mean 1000×1024 bytes. The megabyte is commonly used to measure either 10002 bytes or 10242 bytes, the interpretation of using base 1024 originated as a compromise technical jargon for the byte multiples that needed to be expressed by the powers of 2 but lacked a convenient name. As 1024 approximates 1000, roughly corresponding to the SI prefix kilo-, in 1998 the International Electrotechnical Commission proposed standards for binary prefixes requiring the use of megabyte to strictly denote 10002 bytes and mebibyte to denote 10242 bytes. By the end of 2009, the IEC Standard had been adopted by the IEEE, EU, ISO, the Mac OS X10.6 file manager is a notable example of this usage in software. Since Snow Leopard, file sizes are reported in decimal units, base 21 MB =1048576 bytes is the definition used by Microsoft Windows in reference to computer memory, such as RAM. This definition is synonymous with the binary prefix mebibyte. Mixed 1 MB =1024000 bytes is the used to describe the formatted capacity of the 1.44 MB3. 5inch HD floppy disk. Semiconductor memory doubles in size for each address lane added to an integrated circuit package, the capacity of a disk drive is the product of the sector size, number of sectors per track, number of tracks per side, and the number of disk platters in the drive. Changes in any of these factors would not usually double the size, sector sizes were set as powers of two for convenience in processing. It was an extension to give the capacity of a disk drive in multiples of the sector size, giving a mix of decimal. Depending on compression methods and file format, a megabyte of data can roughly be, a 4 megapixel JPEG image with normal compression. Approximately 1 minute of 128 kbit/s MP3 compressed music,6 seconds of uncompressed CD audio. A typical English book volume in plain text format, the human genome consists of DNA representing 800 MB of data
Megabyte
–
1.44 MB
floppy disks can store 1,474,560 bytes of data. MB in this context means 1,000×1,024 bytes.
14.
Magneto-optical drive
–
A magneto-optical drive is a kind of optical disc drive capable of writing and rewriting data upon a magneto-optical disc. Both 130 mm and 90 mm form factors exist, the technology was introduced commercially in 1985. Although optical, they appear as hard drives to the operating system. Magneto-optical drives were common in countries, such as Japan because of the success of the Sony MiniDisc. Early drives are 130 mm and have the size of full-height 130 mm hard-drives,130 mm media looks similar to a CD-ROM enclosed in an old-style caddy, while 90 mm media is about the size of a regular 3½-inch floppy disk, but twice the thickness. The cases provide dust resistance, and the drives themselves have slots constructed in such a way that always appear to be closed. Original MO systems were WORM, and later systems were read/write, the disc consists of a ferromagnetic material sealed beneath a plastic coating. The only physical contact is during recording when a head is brought into contact with the side of the disc opposite to the laser. During reading, a laser projects a beam on the disk and, according to the state of the surface. During recording, laser power is increased to heat the material to the Curie point in a single spot and this enables an electromagnet positioned on the opposite side of the disc, to change the local magnetic polarization. The polarization is retained after the temperature drops, each write cycle requires both a pass to erase a region, and another pass to write information. Both passes use the laser to heat the recording layer, the field is used for actually changing the magnetic orientation of the recording layer. The electromagnet reverses polarity for writing, and the laser is pulsed to record spots of 1 over the region of 0. As a result of this process, it takes twice as long to write data as it does to read it. In 1996, Direct Overwrite technology was introduced for 90 mm discs eliminating the initial pass when writing. By default, magneto-optical drives verify information after writing it to the disc, using a magneto-optical disc is much more like using a diskette drive than a CD-RW drive. During a read cycle, the laser is operated at a power setting, emitting polarized light. The reflected light has a change in Kerr rotation and Kerr ellipticity which is measured by an analyzer, the 130 mm drives have been available in capacities from 650 MB to 9.2 GB
Magneto-optical drive
–
A Magneto-optical disc and the numerous rectangles on its surface.
Magneto-optical drive
–
A 130 mm 2.6GB magneto-optical disc.
Magneto-optical drive
–
A 230 MB Fujitsu 90 mm magneto-optical disc.
Magneto-optical drive
–
Minidiscs are magneto-optical discs used to store music.
15.
Hard disk
–
The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a manner, meaning that individual blocks of data can be stored or retrieved in any order. HDDs are a type of storage, retaining stored data even when powered off. Introduced by IBM in 1956, HDDs became the dominant secondary storage device for computers by the early 1960s. Continuously improved, HDDs have maintained this position into the era of servers. More than 200 companies have produced HDDs historically, though after extensive industry consolidation most current units are manufactured by Seagate, Toshiba, as of 2016, HDD production is growing, although unit shipments and sales revenues are declining. While SSDs have higher cost per bit, SSDs are replacing HDDs where speed, power consumption, small size, the primary characteristics of an HDD are its capacity and performance. Capacity is specified in unit prefixes corresponding to powers of 1000, the two most common form factors for modern HDDs are 3. 5-inch, for desktop computers, and 2. 5-inch, primarily for laptops. HDDs are connected to systems by standard interface cables such as PATA, SATA, Hard disk drives were introduced in 1956, as data storage for an IBM real-time transaction processing computer and were developed for use with general-purpose mainframe and minicomputers. The first IBM drive, the 350 RAMAC in 1956, was approximately the size of two medium-sized refrigerators and stored five million six-bit characters on a stack of 50 disks. In 1962 the IBM350 RAMAC disk storage unit was superseded by the IBM1301 disk storage unit, cylinder-mode read/write operations were supported, and the heads flew about 250 micro-inches above the platter surface. Motion of the head array depended upon a binary system of hydraulic actuators which assured repeatable positioning. The 1301 cabinet was about the size of three home refrigerators placed side by side, storing the equivalent of about 21 million eight-bit bytes, access time was about a quarter of a second. Also in 1962, IBM introduced the model 1311 disk drive, users could buy additional packs and interchange them as needed, much like reels of magnetic tape. Later models of removable pack drives, from IBM and others, became the norm in most computer installations, non-removable HDDs were called fixed disk drives. Some high-performance HDDs were manufactured with one head per track so that no time was lost physically moving the heads to a track, known as fixed-head or head-per-track disk drives they were very expensive and are no longer in production. In 1973, IBM introduced a new type of HDD code-named Winchester and its primary distinguishing feature was that the disk heads were not withdrawn completely from the stack of disk platters when the drive was powered down. Instead, the heads were allowed to land on an area of the disk surface upon spin-down
Hard disk
–
A 2.5-inch SATA hard drive
Hard disk
–
A disassembled and labeled 1997 HDD lying atop a mirror
Hard disk
–
Recording of single magnetisations of bits on a 200 MB HDD-platter (recording made visible using CMOS-MagView).
Hard disk
–
HDD with disks and motor hub removed exposing copper colored stator coils surrounding a bearing in the center of the spindle motor. Orange stripe along the side of the arm is thin printed-circuit cable, spindle bearing is in the center and the actuator is in the upper left
16.
NeXT MegaPixel Display
–
The NeXT MegaPixel Display was a range of CRT-based computer monitors manufactured and sold by NeXT for the NeXTcube and NeXTstation workstations, designed by Hartmut Esslinger/Frog Design Inc. The original MegaPixel Display was a monochrome 17 monitor displaying 4 brightness levels in a resolution of 1120 x 832 at 92 DPI at 68 Hz. It integrated a mono microphone, mono speaker, stereo RCA sockets, a 3. 5mm headphone socket, a unique feature was that the monitor was connected to the computer by a single 6 foot cable which provided power, video signals and the aforementioned signals. A severe problem with this setup was that the monitor could not be switched off completely while the computer was powered on, the screen could be switched black but the cathode heater always remained on. This led to extreme screen dimming after some years of use and this problem was later rectified with the now ultra rare 4000A model rated at 10,000 hours The display has a stand that allows in to be tilted. The stand also features two rollers that can be used to move the back and forth despite its heavy weight. The stand also provides a place for the keyboard when not in use, X17.3 x 14408 mm x 440 x 35450 lbs. NeXTComputers. org US Patent D312,629 monitor design US Patent D312,630 monitor and stand design US Patent D317,760 stand design US Patent D317,291 cable design
NeXT MegaPixel Display
–
The NeXT MegaPixel Display, sitting on top of a
NeXTstation with the original keyboard & mouse
17.
Computer display
–
A computer monitor or a computer display is an electronic visual display for computers. A monitor usually comprises the display device, circuitry, casing, the display device in modern monitors is typically a thin film transistor liquid crystal display or a flat panel LED display, while older monitors used a cathode ray tubes. It can be connected to the computer via VGA, DVI, HDMI, DisplayPort, Thunderbolt, LVDS or other proprietary connectors, originally, computer monitors were used for data processing while television receivers were used for entertainment. From the 1980s onwards, computers have used for both data processing and entertainment, while televisions have implemented some computer functionality. The common aspect ratio of televisions, and computer monitors, has changed from 4,3 to 16,10, to 16,9. Early electronic computers were fitted with a panel of light bulbs where the state of each particular bulb would indicate the state of a particular register bit inside the computer. This allowed the operating the computer to monitor the internal state of the machine. As early monitors were only capable of displaying a limited amount of information. Instead, a printer was the primary output device, while the monitor was limited to keeping track of the programs operation. Multiple technologies have used for computer monitors. Until the 21st century most used cathode ray tubes but they have largely superseded by LCD monitors. The first computer monitors used cathode ray tubes, high-resolution CRT displays were developed for specialized military, industrial and scientific applications but they were far too costly for general use. Either computer could be connected to the terminals of an ordinary color TV set or used with a purpose-made CRT color monitor for optimum resolution. In 1984 IBM introduced the Enhanced Graphics Adapter which was capable of producing 16 colors and had a resolution of 640 x 350, by the end of the 1980s color CRT monitors that could clearly display 1024 x 768 pixels were widely available and increasingly affordable. During the following decade maximum display resolutions gradually increased and prices continued to fall, CRT technology remained dominant in the PC monitor market into the new millennium partly because it was cheaper to produce and offered viewing angles close to 180 degrees. CRTs still offer some image quality advantages over LCDs but improvements to the latter have made much less obvious. There are multiple technologies that have used to implement liquid crystal displays. Commonly, the laptop would be offered with an assortment of display options at increasing price points, monochrome
Computer display
–
A fixed 19-inch (48 cm), 4:3 rack mount LCD monitor
Computer display
–
The area, height and width of displays with identical diagonal measurements vary dependent on
aspect ratio.
Computer display
–
A 1U stowable clamshell 19-inch (48 cm), 4:3 rack mount LCD monitor with keyboard
Computer display
–
A panel mount 19-inch (48 cm), 4:3 rack mount LCD monitor
18.
Grayscale
–
In photography and computing, a grayscale or greyscale digital image is an image in which the value of each pixel is a single sample, that is, it carries only intensity information. Images of this sort, also known as black-and-white, are composed exclusively of shades of gray, grayscale images are distinct from one-bit bi-tonal black-and-white images, which in the context of computer imaging are images with only two colors, black and white. Grayscale images have many shades of gray in between, but also they can be synthesized from a full color image, see the section about converting to grayscale. The intensity of a pixel is expressed within a range between a minimum and a maximum, inclusive. This range is represented in a way as a range from 0 and 1. This notation is used in papers, but this does not define what black or white is in terms of colorimetry. Another convention is to employ percentages, so the scale is then from 0% to 100%. This is used for an intuitive approach, but if only integer values are used, the range encompasses a total of only 101 intensities. Also, the notation is used in printing to denote how much ink is employed in halftoning. In computing, although the grayscale can be computed through rational numbers, image pixels are stored in binary, the precision provided by this format is barely sufficient to avoid visible banding artifacts, but very convenient for programming because a single pixel then occupies a single byte. Technical uses often require more levels, to full use of the sensor accuracy. Sixteen bits per sample is a convenient choice for such uses, the TIFF and the PNG image file formats support 16-bit grayscale natively, although browsers and many imaging programs tend to ignore the low order 8 bits of each pixel. No matter what pixel depth is used, the binary representations assume that 0 is black, a common strategy is to use the principles of photometry or, more broadly, colorimetry to match the luminance of the grayscale image to the luminance of the original color image. This also ensures that both images will have the absolute luminance, as can be measured in its SI units of candelas per square meter, in any given area of the image. Then, linear luminance is calculated as a sum of the three linear-intensity values. To encode grayscale intensity in linear RGB, each of the three primaries can be set to equal the calculated linear luminance Y, linear luminance typically needs to be gamma compressed to get back to a conventional non-linear representation. In practice, because the three components are then equal, it is only necessary to store these values once in sRGB-compatible image formats that support a single-channel representation. The ITU-R BT.709 standard used for HDTV developed by the ATSC uses different color coefficients, although these are numerically the same coefficients used in sRGB above, the effect is different because here they are being applied directly to gamma-compressed values
Grayscale
–
A sample grayscale image.
19.
Computer speaker
–
Computer speakers, or multimedia speakers, are speakers sold for use with computers, although usually capable of other audio uses, e. g. for an MP3 player. Most such speakers have an amplifier and consequently require a power source. The signal input connector is often a 3.5 mm jack plug, RCA connectors are used. Battery-powered wireless Bluetooth speakers require no connections at all, most computers have speakers of low power and quality built in, when external speakers are connected they disable the built-in speakers. Altec Lansing claims to have created the computer market in 1990. Computer speakers range widely in quality and in price, computer speakers sometimes packaged with computer systems are small, plastic, and have mediocre sound quality. Some computer speakers have equalization features such as bass and treble controls, more sophisticated computer speakers can have a subwoofer unit, to enhance bass output. The larger subwoofer enclosure usually contains the amplifiers for the subwoofer, some computer displays have rather basic speakers built-in. Laptop computers have built-in integrated speakers, usually small and of restricted sound quality to conserve space, instead of using a computer speaker for better sound, a computer can be connected to any external sound system, typically a high-power high-quality setup. It stores energy from the USB connection during quieter periods, delivering power for the peaks. The module is claimed to require less power most of the time, increasing laptop computer battery endurance, and delivering clean, unclipped sound peaks
Computer speaker
–
A pair of speakers for notebook computers that are powered and audio-connected to the computer via USB
20.
Ethernet
–
Ethernet /ˈiːθərnɛt/ is a family of computer networking technologies commonly used in local area networks, metropolitan area networks and wide area networks. It was commercially introduced in 1980 and first standardized in 1983 as IEEE802.3, over time, Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI and ARCNET. The original 10BASE5 Ethernet uses coaxial cable as a medium, while the newer Ethernet variants use twisted pair. Over the course of its history, Ethernet data transfer rates have increased from the original 2.94 megabits per second to the latest 100 gigabits per second. The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet, systems communicating over Ethernet divide a stream of data into shorter pieces called frames. As per the OSI model, Ethernet provides services up to, since its commercial release, Ethernet has retained a good degree of backward compatibility. Features such as the 48-bit MAC address and Ethernet frame format have influenced other networking protocols, the primary alternative for some uses of contemporary LANs is Wi-Fi, a wireless protocol standardized as IEEE802.11. Ethernet was developed at Xerox PARC between 1973 and 1974 and it was inspired by ALOHAnet, which Robert Metcalfe had studied as part of his PhD dissertation. In 1975, Xerox filed a patent application listing Metcalfe, David Boggs, Chuck Thacker, in 1976, after the system was deployed at PARC, Metcalfe and Boggs published a seminal paper. Metcalfe left Xerox in June 1979 to form 3Com and he convinced Digital Equipment Corporation, Intel, and Xerox to work together to promote Ethernet as a standard. The so-called DIX standard, for Digital/Intel/Xerox, specified 10 Mbit/s Ethernet, with 48-bit destination and source addresses and it was published on September 30,1980 as The Ethernet, A Local Area Network. Data Link Layer and Physical Layer Specifications, version 2 was published in November,1982 and defines what has become known as Ethernet II. Formal standardization efforts proceeded at the time and resulted in the publication of IEEE802.3 on June 23,1983. Ethernet initially competed with two largely proprietary systems, Token Ring and Token Bus, in the process, 3Com became a major company. 3Com shipped its first 10 Mbit/s Ethernet 3C100 NIC in March 1981, an Ethernet adapter card for the IBM PC was released in 1982, and, by 1985, 3Com had sold 100,000. Parallel port based Ethernet adapters were produced for a time, with drivers for DOS, by the early 1990s, Ethernet became so prevalent that it was a must-have feature for modern computers, and Ethernet ports began to appear on some PCs and most workstations. This process was sped up with the introduction of 10BASE-T and its relatively small modular connector. Since then, Ethernet technology has evolved to meet new bandwidth, in addition to computers, Ethernet is now used to interconnect appliances and other personal devices
Ethernet
–
A
Cat 5e connection on a
laptop, used for Ethernet
Ethernet
–
An
8P8C modular connector (
often called RJ45) commonly used on
Cat 5 cables in Ethernet networks
Ethernet
–
An Intel 82574L Gigabit Ethernet NIC, PCI Express x1 card
Ethernet
21.
Die-casting
–
Die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity. The mold cavity is created using two hardened steel dies which have been machined into shape and work similarly to an injection mold during the process. Most die castings are made from metals, specifically zinc, copper, aluminium, magnesium, lead, pewter. Depending on the type of metal being cast, a hot- or cold-chamber machine is used, the casting equipment and the metal dies represent large capital costs and this tends to limit the process to high-volume production. Manufacture of parts using die casting is relatively simple, involving only four main steps and it is especially suited for a large quantity of small- to medium-sized castings, which is why die casting produces more castings than any other casting process. Die castings are characterized by a good surface finish and dimensional consistency. Two variants are pore-free die casting, which is used to eliminate gas porosity defects, and direct injection die casting, Die casting equipment was invented in 1838 for the purpose of producing movable type for the printing industry. The first die casting-related patent was granted in 1849 for a small hand-operated machine for the purpose of mechanized printing type production, in 1885 Otto Mergenthaler invented the linotype machine, an automated type-casting device which became the prominent type of equipment in the publishing industry. The Soss die-casting machine, manufactured in Brooklyn, NY, was the first machine to be sold in the market in North America. Other applications grew rapidly, with die casting facilitating the growth of consumer goods, in 1966, General Motors released the Acurad process. The main die casting alloys are, zinc, aluminium, magnesium, copper, lead, specific die casting alloys include, Zamak, zinc aluminium, aluminium to, e. g. The Aluminum Association standards, AA380, AA384, AA386, AA390, and AZ91D magnesium. The following is a summary of the advantages of each alloy, Zinc, magnesium, the easiest metal to machine, excellent strength-to-weight ratio, lightest alloy commonly die cast. Silicon tombac, high-strength alloy made of copper, zinc and silicon, often used as an alternative for investment casted steel parts. Lead and tin, high density, extremely close dimensional accuracy, such alloys are not used in foodservice applications for public health reasons. Type metal, an alloy of lead, tin and antimony is used for casting hand-set type in letterpress printing, traditionally cast in hand jerk moulds now predominantly die cast after the industrialisation of the type foundries. Around 1900 the slug casting machines came onto the market and added further automation, maximum weight limits for aluminium, brass, magnesium and zinc castings are approximately 70 pounds,10 lb,44 lb, and 75 lb, respectively. The material used defines the minimum thickness and minimum draft required for a casting as outlined in the table below
Die-casting
–
An engine block with aluminium and magnesium die castings.
Die-casting
–
Open tooling and injection nozzle
Die-casting
–
Complete working cell
Die-casting
–
The ejector die half
22.
Magnesium
–
Magnesium is a chemical element with symbol Mg and atomic number 12. Magnesium is the ninth most abundant element in the universe and it is produced in large, aging stars from the sequential addition of three helium nuclei to a carbon nucleus. When such stars explode as supernovas, much of the magnesium is expelled into the medium where it may recycle into new star systems. Magnesium is the eighth most abundant element in the Earths crust and the fourth most common element in the Earth, making up 13% of the planets mass and it is the third most abundant element dissolved in seawater, after sodium and chlorine. Magnesium occurs naturally only in combination with elements, where it invariably has a +2 oxidation state. The free element can be produced artificially, and is highly reactive, the free metal burns with a characteristic brilliant-white light. The metal is now obtained mainly by electrolysis of magnesium salts obtained from brine, Magnesium is less dense than aluminium, and the alloy is prized for its combination of lightness and strength. Magnesium is the eleventh most abundant element by mass in the body and is essential to all cells. Magnesium ions interact with polyphosphate compounds such as ATP, DNA, hundreds of enzymes require magnesium ions to function. Magnesium compounds are used medicinally as common laxatives, antacids, elemental magnesium is a gray-white lightweight metal, two-thirds the density of aluminium. Magnesium has the lowest melting and the lowest boiling point 1,363 K of all the alkaline earth metals, Magnesium reacts with water at room temperature, though it reacts much more slowly than calcium, a similar group 2 metal. When submerged in water, hydrogen bubbles form slowly on the surface of the metal—though, if powdered, the reaction occurs faster with higher temperatures. Magnesiums reversible reaction with water can be harnessed to store energy, Magnesium also reacts exothermically with most acids such as hydrochloric acid, producing the metal chloride and hydrogen gas, similar to the HCl reaction with aluminium, zinc, and many other metals. Magnesium is highly flammable, especially when powdered or shaved into thin strips, flame temperatures of magnesium and magnesium alloys can reach 3,100 °C, although flame height above the burning metal is usually less than 300 mm. Once ignited, such fires are difficult to extinguish, with combustion continuing in nitrogen, carbon dioxide, Magnesium may also be used as an igniter for thermite, a mixture of aluminium and iron oxide powder that ignites only at a very high temperature. When burning in air, magnesium produces a light that includes strong ultraviolet wavelengths. Magnesium powder was used for illumination in the early days of photography. Later, magnesium filament was used in electrically ignited single-use photography flashbulbs, Magnesium powder is used in fireworks and marine flares where a brilliant white light is required
Magnesium
–
Magnesium, 12 Mg
Magnesium
–
Spectral lines of magnesium
Magnesium
–
Magnesium sheets and ingots
Magnesium
–
An unusual application of magnesium as an
illumination source while
wakeskating in 1931
23.
NeXTcube
–
The NeXTcube is a high-end workstation computer developed, manufactured, and sold by NeXT from 1990 until 1993. It superseded the original NeXT Computer workstation and is housed in a similar cube-shaped magnesium enclosure, the workstation runs the NeXTSTEP operating system and was launched with a US$10,000 list price. The NeXTcube was the successor to the original NeXT Computer and it differs from its predecessor in having a 25 MHz 68040 processor, larger hard disks in place of the magneto-optical drive, and an optional floppy disk drive. A33 MHz NeXTcube Turbo was produced later, NeXT released the NeXTdimension for the NeXTcube, a circuit board based on an Intel i860 processor, which offers 32-bit PostScript color display and video sampling features. The Pyro accelerator board increases the speed of a NeXTcube by replacing the standard 25 MHz processor with a 50 MHz one, NeXT character set old-computers. com — NeXTcube NeXTComputers. org Photo gallery of NeXT hardware
NeXTcube
–
The base NeXTcube model
NeXTcube
–
NeXTcube with original screen, keyboard and mouse.
24.
Mach (kernel)
–
Mach is a kernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computing. Mach is often mentioned as one of the earliest examples of a microkernel, however, not all versions of Mach are microkernels. Machs derivatives are the basis of the operating system kernels in GNU Hurd. The project at Carnegie Mellon ran from 1985 to 1994, ending with Mach 3.0, Mach was developed as a replacement for the kernel in the BSD version of Unix, so no new operating system would have to be designed around it. Experimental research on Mach appears to have ended, although Mach and these include NeXTSTEP and OpenStep, upon which macOS is based—all using the XNU operating system kernel which incorporates an earlier, non-microkernel, Mach as a major component. The Mach virtual memory management system was adopted in 4. 4BSD by the BSD developers at CSRG. Mach is the successor to Carnegie Mellons Accent kernel. The lead developer on the Mach project, Richard Rashid, has been working at Microsoft since 1991 in various top-level positions revolving around the Microsoft Research division. Another of the original Mach developers, Avie Tevanian, was head of software at NeXT. Rashid liked Giuses spelling Mach so much that it prevailed, a key concept in the original Unix operating system was the idea of a pipe. A pipe was an abstraction that allowed data to be moved from program to program using the command line, using pipes, users could link together multiple programs to complete tasks, feeding data through several small programs in turn. Pipes were built on the underlying input/output system and this system was, in turn, based on a model where drivers were expected to periodically block while they waited for tasks to complete. For instance, a driver might send a line of text to a line printer. In this case, the driver would indicate that it was blocked, in the pipes system the limited resource was memory, and when one program filled the memory assigned to the pipe, it would naturally block. Normally this would cause the program to run, emptying the pipe out again. However, the implementation of pipes as memory buffers meant data was being copied from program to program and this made the pipe concept unsuitable for tasks where quick turnaround or low latency was needed, as is the case in most device drivers. The operating system kernel and most core functionality was instead written as a large program. As the operating system added new functionality, the size and complexity of the kernel grew, Unix pipes offered a conceptual system that could be used to build arbitrarily complex solutions out of small interacting programs
Mach (kernel)
–
Academics
25.
Berkeley Software Distribution
–
Berkeley Software Distribution is a Unix operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995. Today the term BSD is often used non-specifically to refer to any of the BSD descendants which together form a branch of the family of Unix-like operating systems, operating systems derived from the original BSD code remain actively developed and widely used. Historically, BSD has been considered a branch of Unix, Berkeley Unix, because it shared the initial codebase, in the 1980s, BSD was widely adopted by vendors of workstation-class systems in the form of proprietary Unix variants such as DEC ULTRIX and Sun Microsystems SunOS. This can be attributed to the ease with which it could be licensed, FreeBSD, OpenBSD, NetBSD, Darwin, and PC-BSD. The earliest distributions of Unix from Bell Labs in the 1970s included the source code to the system, allowing researchers at universities to modify. A larger PDP-11/70 was installed at Berkeley the following year, using money from the Ingres database project, also in 1975, Ken Thompson took a sabbatical from Bell Labs and came to Berkeley as a visiting professor. He helped to install Version 6 Unix and started working on a Pascal implementation for the system, graduate students Chuck Haley and Bill Joy improved Thompsons Pascal and implemented an improved text editor, ex. Other universities became interested in the software at Berkeley, and so in 1977 Joy started compiling the first Berkeley Software Distribution, 1BSD was an add-on to Version 6 Unix rather than a complete operating system in its own right. Some thirty copies were sent out, some 75 copies of 2BSD were sent out by Bill Joy. 2. 9BSD from 1983 included code from 4. 1cBSD, the most recent release,2. 11BSD, was first issued in 1992. As of 2008, maintenance updates from volunteers are still continuing, a VAX computer was installed at Berkeley in 1978, but the port of Unix to the VAX architecture, UNIX/32V, did not take advantage of the VAXs virtual memory capabilities. 3BSD was also alternatively called Virtual VAX/UNIX or VMUNIX, and BSD kernel images were normally called /vmunix until 4. 4BSD, 4BSD offered a number of enhancements over 3BSD, notably job control in the previously released csh, delivermail, reliable signals, and the Curses programming library. In a 1985 review of BSD releases, John Quarterman et al, many installations inside the Bell System ran 4. 1BSD. 4. 1BSD was a response to criticisms of BSDs performance relative to the dominant VAX operating system, the 4. 1BSD kernel was systematically tuned up by Bill Joy until it could perform as well as VMS on several benchmarks. Back at Bell Labs,4. 1cBSD became the basis of the 8th Edition of Research Unix, to guide the design of 4. The committee met from April 1981 to June 1983, apart from the Fast File System, several features from outside contributors were accepted, including disk quotas and job control. Sun Microsystems provided testing on its Motorola 68000 machines prior to release, the official 4. 2BSD release came in August 1983. On a lighter note, it marked the debut of BSDs daemon mascot in a drawing by John Lasseter that appeared on the cover of the printed manuals distributed by USENIX
Berkeley Software Distribution
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BSD
Berkeley Software Distribution
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The
DEC VT100 terminal, widely used for
Unix timesharing
Berkeley Software Distribution
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The
VAX-11/780, a typical minicomputer used for early BSD timesharing systems
Berkeley Software Distribution
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VAX-11/780 internals
26.
Unix
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Among these is Apples macOS, which is the Unix version with the largest installed base as of 2014. Many Unix-like operating systems have arisen over the years, of which Linux is the most popular, Unix was originally meant to be a convenient platform for programmers developing software to be run on it and on other systems, rather than for non-programmer users. The system grew larger as the system started spreading in academic circles, as users added their own tools to the system. Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration and these concepts are collectively known as the Unix philosophy. By the early 1980s users began seeing Unix as a universal operating system. Under Unix, the system consists of many utilities along with the master control program. To mediate such access, the kernel has special rights, reflected in the division between user space and kernel space, the microkernel concept was introduced in an effort to reverse the trend towards larger kernels and return to a system in which most tasks were completed by smaller utilities. In an era when a standard computer consisted of a disk for storage and a data terminal for input and output. However, modern systems include networking and other new devices, as graphical user interfaces developed, the file model proved inadequate to the task of handling asynchronous events such as those generated by a mouse. In the 1980s, non-blocking I/O and the set of inter-process communication mechanisms were augmented with Unix domain sockets, shared memory, message queues, and semaphores. In microkernel implementations, functions such as network protocols could be moved out of the kernel, Multics introduced many innovations, but had many problems. Frustrated by the size and complexity of Multics but not by the aims and their last researchers to leave Multics, Ken Thompson, Dennis Ritchie, M. D. McIlroy, and J. F. Ossanna, decided to redo the work on a much smaller scale. The name Unics, a pun on Multics, was suggested for the project in 1970. Peter H. Salus credits Peter Neumann with the pun, while Brian Kernighan claims the coining for himself, in 1972, Unix was rewritten in the C programming language. Bell Labs produced several versions of Unix that are referred to as Research Unix. In 1975, the first source license for UNIX was sold to faculty at the University of Illinois Department of Computer Science, UIUC graduate student Greg Chesson was instrumental in negotiating the terms of this license. During the late 1970s and early 1980s, the influence of Unix in academic circles led to adoption of Unix by commercial startups, including Sequent, HP-UX, Solaris, AIX. In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4, in the 1990s, Unix-like systems grew in popularity as Linux and BSD distributions were developed through collaboration by a worldwide network of programmers
Unix
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Ken Thompson (sitting) and
Dennis Ritchie working together at a
PDP-11
Unix
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Evolution of Unix and Unix-like systems
Unix
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Ken Thompson and
Dennis Ritchie, principal developers of
Research Unix
Unix
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Photo from
USENIX 1984, including
Dennis Ritchie (center)
27.
War Memorial Opera House
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The War Memorial Opera House in San Francisco, California is located on the western side of Van Ness Avenue across from the rear facade of City Hall. It is part of the San Francisco War Memorial and Performing Arts Center and it has been the home of the San Francisco Opera since opening night in 1932. In 1927, $4 million in bonds were issued to finance the design. A colonnade of paired columns screens colossal arch-headed windows above a rusticated basement. The interior contains an entrance hall with a high barrel vaulted and coffered ceiling parallel to the street. The theater space is dominated by an aluminum and glass panel chandelier under a blue vault. The theater has 3,146 seats plus standing room for 200 behind the orchestra and this is smaller than the Metropolitan Opera and the Chicago Lyric Opera, but it follows the trend of larger capacity in American opera houses than the main European opera houses of the 19th century. The San Francisco Symphony performed most of its concerts in the house, RCA Victor recorded the orchestra here, under the direction of Pierre Monteux, from 1941 to 1952 and in a special stereophonic session in January 1960. The orchestra also made a few recordings for RCA with Enrique Jorda in 1957 and 1958, in later years, the orchestra used a special acoustical shell that was placed around the musicians, greatly enhancing acoustics for concerts. The orchestras final concert in the house was an all-Beethoven concert, after the bombing of Pearl Harbor, the house was regularly blacked out and performances were monitored by air raid wardens. In spring of 1945, the United Nations had its first conference there, the UN Charter was later drafted and signed in the Herbst Theatre next door. Six years later in 1951, the Treaty of San Francisco was drafted and signed here, during the years of Kurt Herbert Adlers general directorship, the inadequacies of the house became apparent as the season was expanded. In particular, there was a lack of space and rehearsal space. In 1974, The Pointer Sisters were the first pop act to perform at the theatre, in 1979 the backstage area was extended, followed in 1981 by the opening of a new wing built onto the house on the Franklin Street side. This gave spaces for sets, coaches, and dancers as well as administrative space. At the same time, the nearby Zellerbach Rehearsal Hall, with a stage the size as that of the Opera House, was opened as part of the complex which included the Louise M. Davies Symphony Hall. In 1989, the powerful Loma Prieta earthquake that shook the Bay Area caused major damage to the Opera House, at this time additional private donations were raised for extensive technical improvements. The organ is not needed with the completion of the nearby Davies Symphony Hall, an underground extension below the neighboring plaza to accommodate additional dressing rooms and backstage facilities
War Memorial Opera House
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War Memorial Opera House
War Memorial Opera House
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The lobby has staircases with overlooks at each end and entrances to the main level at left.
War Memorial Opera House
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Stage and proscenium
War Memorial Opera House
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War Memorial Opera House Dress Circle & Balcony levels
28.
San Francisco
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San Francisco, officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California. It is the birthplace of the United Nations, the California Gold Rush of 1849 brought rapid growth, making it the largest city on the West Coast at the time. San Francisco became a consolidated city-county in 1856, after three-quarters of the city was destroyed by the 1906 earthquake and fire, San Francisco was quickly rebuilt, hosting the Panama-Pacific International Exposition nine years later. In World War II, San Francisco was a port of embarkation for service members shipping out to the Pacific Theater. Politically, the city votes strongly along liberal Democratic Party lines, San Francisco is also the headquarters of five major banking institutions and various other companies such as Levi Strauss & Co. Dolby, Airbnb, Weebly, Pacific Gas and Electric Company, Yelp, Pinterest, Twitter, Uber, Lyft, Mozilla, Wikimedia Foundation, as of 2016, San Francisco is ranked high on world liveability rankings. The earliest archaeological evidence of habitation of the territory of the city of San Francisco dates to 3000 BC. Upon independence from Spain in 1821, the became part of Mexico. Under Mexican rule, the system gradually ended, and its lands became privatized. In 1835, Englishman William Richardson erected the first independent homestead, together with Alcalde Francisco de Haro, he laid out a street plan for the expanded settlement, and the town, named Yerba Buena, began to attract American settlers. Commodore John D. Sloat claimed California for the United States on July 7,1846, during the Mexican–American War, montgomery arrived to claim Yerba Buena two days later. Yerba Buena was renamed San Francisco on January 30 of the next year, despite its attractive location as a port and naval base, San Francisco was still a small settlement with inhospitable geography. The California Gold Rush brought a flood of treasure seekers, with their sourdough bread in tow, prospectors accumulated in San Francisco over rival Benicia, raising the population from 1,000 in 1848 to 25,000 by December 1849. The promise of fabulous riches was so strong that crews on arriving vessels deserted and rushed off to the gold fields, leaving behind a forest of masts in San Francisco harbor. Some of these approximately 500 abandoned ships were used at times as storeships, saloons and hotels, many were left to rot, by 1851 the harbor was extended out into the bay by wharves while buildings were erected on piles among the ships. By 1870 Yerba Buena Cove had been filled to create new land, buried ships are occasionally exposed when foundations are dug for new buildings. California was quickly granted statehood in 1850 and the U. S. military built Fort Point at the Golden Gate, silver discoveries, including the Comstock Lode in Nevada in 1859, further drove rapid population growth. With hordes of fortune seekers streaming through the city, lawlessness was common, and the Barbary Coast section of town gained notoriety as a haven for criminals, prostitution, entrepreneurs sought to capitalize on the wealth generated by the Gold Rush
San Francisco
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San Francisco and the
Golden Gate Bridge from
Marin Headlands
San Francisco
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Mission San Francisco de Asís (Mission Dolores)
San Francisco
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1853
United States Coast Survey Map
San Francisco
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Francis Samuel Marryat, Hilltop of San Francisco, California, Looking toward the Bay, 1849. M.& N. Hanhart Chromolithograph
29.
Steve Jobs
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Steven Paul Steve Jobs was an American entrepreneur, businessman, inventor, and industrial designer. He was the co-founder, chairman, and chief officer of Apple Inc. CEO and majority shareholder of Pixar, a member of The Walt Disney Companys board of directors following its acquisition of Pixar, and founder, chairman, Jobs and Apple co-founder Steve Wozniak are widely recognized as pioneers of the microcomputer revolution of the 1970s and 1980s. Jobs was born in San Francisco and adopted at birth, he was raised in the San Francisco Bay Area during the 1960s, Jobs briefly attended Reed College in 1972 before dropping out. He then decided to travel through India in 1974 seeking enlightenment, Jobss declassified FBI report stated that an acquaintance knew that Jobs had used the illegal drugs marijuana and LSD while he was in college. Jobs once told a reporter that taking LSD was one of the two or three most important things he did in his life, Jobs and Wozniak co-founded Apple in 1976 to sell Wozniaks Apple I personal computer. The visionaries gained fame and wealth a year later for the Apple II, in 1979, after a tour of PARC, Jobs saw the commercial potential of the Xerox Alto, which was mouse-driven and had a graphical user interface. This led to development of the unsuccessful Apple Lisa in 1983, following a long power struggle, Jobs was forced out of Apple in 1985. In addition, Jobs helped to initiate the development of the effects industry when he funded the spinout of the computer graphics division of George Lucass Lucasfilm in 1986. The new company, Pixar, would produce the first fully computer-animated film. In 1997, Apple merged with NeXT, within a few months of the merger, Jobs became CEO of his former company, reviving Apple at the verge of bankruptcy. Mac OS was also revamped into OS X, based on NeXTs NeXTSTEP platform, Jobs was diagnosed with a pancreatic neuroendocrine tumor in 2003 and died on October 5,2011 of respiratory arrest related to the tumor. Steve Jobss biological father, Abdulfattah John Jandali, was born into a Muslim household and grew up in Homs, Jandali is the son of a self-made millionaire who did not go to college and a mother who was a traditional housewife. While an undergraduate at the American University of Beirut, he was a student activist, although Jandali initially wanted to study law, he eventually decided to study economics and political science. He pursued a PhD in the subject at the University of Wisconsin, where he met Joanne Carole Schieble, a Catholic of Swiss and German descent. As a doctoral candidate, Jandali was an assistant for a course Schieble was taking. Mona Simpson, notes that her grandparents were not happy that their daughter was dating Jandali. But there are a lot of Arabs in Michigan and Wisconsin, Walter Isaacson, Steve Jobss official biographer, additionally states that Schiebles father threatened to cut Joanne off completely if she continued the relationship
Steve Jobs
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Jobs in 2007
Steve Jobs
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Childhood home of Steve Jobs in
Los Altos, California that served as the original site of
Apple Computer. The home was added to a list of historic Los Altos sites in 2013.
Steve Jobs
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Steve Jobs with
Wendell Brown at the launch of Brown's Hippo-C software for Macintosh, January 1984
Steve Jobs
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Steve Jobs's house in Palo Alto
30.
BYTE
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The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of used to encode a single character of text in a computer. The size of the byte has historically been hardware dependent and no standards existed that mandated the size. The de-facto standard of eight bits is a convenient power of two permitting the values 0 through 255 for one byte, the international standard IEC 80000-13 codified this common meaning. Many types of applications use information representable in eight or fewer bits, the popularity of major commercial computing architectures has aided in the ubiquitous acceptance of the 8-bit size. The unit symbol for the byte was designated as the upper-case letter B by the IEC and IEEE in contrast to the bit, internationally, the unit octet, symbol o, explicitly denotes a sequence of eight bits, eliminating the ambiguity of the byte. It is a respelling of bite to avoid accidental mutation to bit. Early computers used a variety of four-bit binary coded decimal representations and these representations included alphanumeric characters and special graphical symbols. S. Government and universities during the 1960s, the prominence of the System/360 led to the ubiquitous adoption of the eight-bit storage size, while in detail the EBCDIC and ASCII encoding schemes are different. In the early 1960s, AT&T introduced digital telephony first on long-distance trunk lines and these used the eight-bit µ-law encoding. This large investment promised to reduce costs for eight-bit data. The development of microprocessors in the 1970s popularized this storage size. A four-bit quantity is called a nibble, also nybble. The term octet is used to specify a size of eight bits. It is used extensively in protocol definitions, historically, the term octad or octade was used to denote eight bits as well at least in Western Europe, however, this usage is no longer common. The exact origin of the term is unclear, but it can be found in British, Dutch, and German sources of the 1960s and 1970s, and throughout the documentation of Philips mainframe computers. The unit symbol for the byte is specified in IEC 80000-13, IEEE1541, in the International System of Quantities, B is the symbol of the bel, a unit of logarithmic power ratios named after Alexander Graham Bell, creating a conflict with the IEC specification. However, little danger of confusion exists, because the bel is a used unit
BYTE
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Percentage difference between decimal and binary interpretations of the unit prefixes grows with increasing storage size
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