The megabyte is a multiple of the unit byte for digital information. Its recommended unit symbol is MB; the unit prefix mega is a multiplier of 1000000 in the International System of Units. Therefore, one megabyte is one million bytes of information; this definition has been incorporated into the International System of Quantities. However, in the computer and information technology fields, several other definitions are used that arose for historical reasons of convenience. A common usage has been to designate one megabyte as 1048576bytes, a measurement that conveniently expresses the binary multiples inherent in digital computer memory architectures. However, most standards bodies have deprecated this usage in favor of a set of binary prefixes, in which this quantity is designated by the unit mebibyte. Less common is a convention that used the megabyte to mean 1000×1024 bytes; the megabyte is 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 corresponding to the SI prefix kilo-, it was a convenient term to denote the binary multiple. In 1998 the International Electrotechnical Commission proposed standards for binary prefixes requiring the use of megabyte to 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 and NIST; the term megabyte continues to be used with different meanings: Base 10 1 MB = 1000000 bytes is the definition recommended by the International System of Units and the International Electrotechnical Commission IEC. This definition is used in networking contexts and most storage media hard drives, flash-based storage, DVDs, is consistent with the other uses of the SI prefix in computing, such as CPU clock speeds or measures of performance; the Mac OS X 10.6 file manager is a notable example of this usage in software. Since Snow Leopard, file sizes are reported in decimal units. In this convention, one thousand megabytes is equal to one gigabyte, where 1 GB is one billion bytes.
Base 2 1 MB = 1048576 bytes is the definition used by Microsoft Windows in reference to computer memory, such as RAM. This definition is synonymous with the unambiguous binary prefix mebibyte. In this convention, one thousand and twenty-four megabytes is equal to one gigabyte, where 1 GB is 10243 bytes. Mixed 1 MB = 1024000 bytes is the definition used to describe the formatted capacity of the 1.44 MB 3.5-inch HD floppy disk, which has a capacity of 1474560bytes. Semiconductor memory doubles in size for each address lane added to an integrated circuit package, which favors counts that are powers of two; the capacity of a disk drive is the product of the sector size, number of sectors per track, number of tracks per side, the number of disk platters in the drive. Changes in any of these factors would not double the size. Sector sizes were set as powers of two for convenience in processing, it was a natural extension to give the capacity of a disk drive in multiples of the sector size, giving a mix of decimal and binary multiples when expressing total disk capacity.
Depending on compression methods and file format, a megabyte of data can be: a 1 megapixel bitmap image with 256 colors stored without any compression. A 4 megapixel JPEG image with normal compression. 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. The parts that differentiate one person from another can be compressed to 4 MB. Timeline of binary prefixes Gigabyte § Consumer confusion Historical Notes About The Cost Of Hard Drive Storage Space the megabyte International Electrotechnical Commission definitions IEC prefixes and symbols for binary multiples
A DIN connector is an electrical connector, standardized in the early 1970s by the Deutsches Institut für Normung, the German national standards organization. There are DIN standards for a large number of different connectors, therefore the term "DIN connector" alone does not unambiguously identify any particular type of connector unless the document number of the relevant DIN standard is added; some DIN connector standards are: DIN 41524, for circular connectors used for audio signals or some digital signals like MIDI DIN 41612, rectangular connectors used to connect plug-in cards to a back plane or motherboard DIN 41652 D-subminiature connectors used for computer data and video DIN 41585 automotive coaxial connectorsIn the context of consumer electronics, the term "DIN connector" refers to a member of a family of circular connectors that were standardized by DIN for analog audio signals. Some of these connectors have been used in analog video applications, for power connections and for digital interfaces such as MIDI or the IBM AT computer keyboard.
The original DIN standards for these connectors are no longer in print and have been replaced with the equivalent international standard IEC 60130-9. While DIN connectors appear superficially similar to the professional XLR connectors, they are not compatible. All male connectors of this family of connectors feature a 13.2 mm diameter metal shield with a notch that limits the orientation in which plug and socket can mate. A range of connectors of the same form that differ only in their pin configuration exist and have been standardized in DIN 41524 / IEC/DIN EN 60130-9, DIN 45322, DIN 45329, DIN 45326 / IEC/DIN EN 60130-9, other standards for a range of different applications, including the following examples: The plugs consist of a circular shielding metal skirt protecting a number of straight round pins; the pins are 1.45 mm in diameter and spaced in a 7.0 mm diameter circle. The skirt is keyed to ensure that the plug is inserted with the correct orientation, to prevent damage to the pins.
The basic design ensures that the shielding is connected between socket and plug prior to any signal path connection being made. However, as the keying is consistent across all connectors, it does not prevent incompatible connectors from mating, which can lead to damage. Additionally, some "domino" 5-pin connectors had a keyway on opposing sides of the plug, allowing it to be reversed. If used as a headphone connector, that allowed the left and right channels to be transposed, if used as a serial data connection the transmit and receive lines could be crossed. There are seven common patterns, with any number of pins from three to eight. Three different five-pin connectors exist, known as 180°, 240°, domino/360°/270° after the angle of the arc swept between the first and last pin. There are two variations of the six-pin, seven-pin, eight-pin connectors. There is some limited compatibility. In addition to these connectors, there are connectors with 10, 12, 14 pins; some high-range equipment used seven-pin connectors where the outer two carried digital system data: if the connected equipment was incompatible, the outer two pins could be unscrewed from plugs so that they fitted into standard five-pin 180° sockets without data connections.
Screw-locking versions of this connector have been used in instrumentation, process control, professional audio. In North America, this variant is called a "small Tuchel" connector after one of the major manufacturers, now a division of Amphenol. Additional configurations up to 24 pins are offered in the same shell size. A version with a bayonet locking ring was used on portable tape recorders, dictation machines, lighting dimmers and controls through from the 1960s to the 1980s, an example being the microphone input connector and some others on the "Report" family of Uher tape recorders; the bayonet locking version is sometimes referred to by the trade name Preh. Belling Lee offered a version with a sprung-loaded collar which latched on insertion but required the collar to be pulled back to release the connector, similar to the LEMO B series connector; this connector was referred to as the "Bleecon", an example of its use being the Strand Tempus range of theatrical lighting dimmers and control desks.
A version with a pushbutton latch similar to that on an XLR cable mounted socket was available. Female connectors with screw-locking, Bleecon, or bayonet latching features are compatible with standard DIN plugs; some manufacturers offered panel-mounted jacks with potential-free auxiliary contacts that would open if a plug were inserted. A polarised two-pin unshielded connector, designed for connecting a loudspeaker to a power amplifier, is known as the DIN 41529 loudspeaker connector, it exists as a panel-mounting female version, line-mounted male and female versions. The male version has a central flat p
A motherboard is the main printed circuit board found in general purpose computers and other expandable systems. It holds and allows communication between many of the crucial electronic components of a system, such as the central processing unit and memory, provides connectors for other peripherals. Unlike a backplane, a motherboard contains significant sub-systems such as the central processor, the chipset's input/output and memory controllers, interface connectors, other components integrated for general purpose use and applications. Motherboard refers to a PCB with expansion capability and as the name suggests, this board is referred to as the "mother" of all components attached to it, which include peripherals, interface cards, daughtercards: sound cards, video cards, network cards, hard drives, or other forms of persistent storage; the term mainboard is applied to devices with a single board and no additional expansions or capability, such as controlling boards in laser printers, washing machines, mobile phones and other embedded systems with limited expansion abilities.
Prior to the invention of the microprocessor, the digital computer consisted of multiple printed circuit boards in a card-cage case with components connected by a backplane, a set of interconnected sockets. In old designs, copper wires were the discrete connections between card connector pins, but printed circuit boards soon became the standard practice; the Central Processing Unit and peripherals were housed on individual printed circuit boards, which were plugged into the backplane. The ubiquitous S-100 bus of the 1970s is an example of this type of backplane system; the most popular computers of the 1980s such as the Apple II and IBM PC had published schematic diagrams and other documentation which permitted rapid reverse-engineering and third-party replacement motherboards. Intended for building new computers compatible with the exemplars, many motherboards offered additional performance or other features and were used to upgrade the manufacturer's original equipment. During the late 1981s and early 1990s, it became economical to move an increasing number of peripheral functions onto the motherboard.
In the late 1980s, personal computer motherboards began to include single ICs capable of supporting a set of low-speed peripherals: keyboard, floppy disk drive, serial ports, parallel ports. By the late 1990s, many personal computer motherboards included consumer-grade embedded audio, video and networking functions without the need for any expansion cards at all. Business PCs, servers were more to need expansion cards, either for more robust functions, or for higher speeds. Laptop and notebook computers that were developed in the 1990s integrated the most common peripherals; this included motherboards with no upgradeable components, a trend that would continue as smaller systems were introduced after the turn of the century. Memory, network controllers, power source, storage would be integrated into some systems. A motherboard provides the electrical connections by which the other components of the system communicate. Unlike a backplane, it contains the central processing unit and hosts other subsystems and devices.
A typical desktop computer has its microprocessor, main memory, other essential components connected to the motherboard. Other components such as external storage, controllers for video display and sound, peripheral devices may be attached to the motherboard as plug-in cards or via cables. An important component of a motherboard is the microprocessor's supporting chipset, which provides the supporting interfaces between the CPU and the various buses and external components; this chipset determines, to an extent, the capabilities of the motherboard. Modern motherboards include: Sockets. In the case of CPUs in ball grid array packages, such as the VIA C3, the CPU is directly soldered to the motherboard. Memory Slots into which the system's main memory is to be installed in the form of DIMM modules containing DRAM chips A chipset which forms an interface between the CPU's front-side bus, main memory, peripheral buses Non-volatile memory chips containing the system's firmware or BIOS A clock generator which produces the system clock signal to synchronize the various components Slots for expansion cards Power connectors, which receive electrical power from the computer power supply and distribute it to the CPU, main memory, expansion cards.
As of 2007, some graphics cards require more power than the motherboard can provide, thus dedicated connectors have been introduced to attach them directly to the power supply. Connectors for hard drives SATA only. Disk drives connect to the power supply. Additionally, nearly all motherboards include logic and connectors to support used input devices, such as USB for mouse devices and keyboards. Early personal computers
Microsoft Windows is a group of several graphical operating system families, all of which are developed and sold by Microsoft. Each family caters to a certain sector of the computing industry. Active Windows families include Windows Embedded. Defunct Windows families include Windows Mobile and Windows Phone. Microsoft introduced an operating environment named Windows on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces. Microsoft Windows came to dominate the world's personal computer market with over 90% market share, overtaking Mac OS, introduced in 1984. Apple came to see Windows as an unfair encroachment on their innovation in GUI development as implemented on products such as the Lisa and Macintosh. On PCs, Windows is still the most popular operating system. However, in 2014, Microsoft admitted losing the majority of the overall operating system market to Android, because of the massive growth in sales of Android smartphones.
In 2014, the number of Windows devices sold was less than 25 %. This comparison however may not be relevant, as the two operating systems traditionally target different platforms. Still, numbers for server use of Windows show one third market share, similar to that for end user use; as of October 2018, the most recent version of Windows for PCs, tablets and embedded devices is Windows 10. The most recent versions for server computers is Windows Server 2019. A specialized version of Windows runs on the Xbox One video game console. Microsoft, the developer of Windows, has registered several trademarks, each of which denote a family of Windows operating systems that target a specific sector of the computing industry; as of 2014, the following Windows families are being developed: Windows NT: Started as a family of operating systems with Windows NT 3.1, an operating system for server computers and workstations. It now consists of three operating system subfamilies that are released at the same time and share the same kernel: Windows: The operating system for mainstream personal computers and smartphones.
The latest version is Windows 10. The main competitor of this family is macOS by Apple for personal computers and Android for mobile devices. Windows Server: The operating system for server computers; the latest version is Windows Server 2019. Unlike its client sibling, it has adopted a strong naming scheme; the main competitor of this family is Linux. Windows PE: A lightweight version of its Windows sibling, meant to operate as a live operating system, used for installing Windows on bare-metal computers, recovery or troubleshooting purposes; the latest version is Windows PE 10. Windows IoT: Initially, Microsoft developed Windows CE as a general-purpose operating system for every device, too resource-limited to be called a full-fledged computer. However, Windows CE was renamed Windows Embedded Compact and was folded under Windows Compact trademark which consists of Windows Embedded Industry, Windows Embedded Professional, Windows Embedded Standard, Windows Embedded Handheld and Windows Embedded Automotive.
The following Windows families are no longer being developed: Windows 9x: An operating system that targeted consumers market. Discontinued because of suboptimal performance. Microsoft now caters to the consumer market with Windows NT. Windows Mobile: The predecessor to Windows Phone, it was a mobile phone operating system; the first version was called Pocket PC 2000. The last version is Windows Mobile 6.5. Windows Phone: An operating system sold only to manufacturers of smartphones; the first version was Windows Phone 7, followed by Windows Phone 8, the last version Windows Phone 8.1. It was succeeded by Windows 10 Mobile; the term Windows collectively describes any or all of several generations of Microsoft operating system products. These products are categorized as follows: The history of Windows dates back to 1981, when Microsoft started work on a program called "Interface Manager", it was announced in November 1983 under the name "Windows", but Windows 1.0 was not released until November 1985.
Windows 1.0 was to achieved little popularity. Windows 1.0 is not a complete operating system. The shell of Windows 1.0 is a program known as the MS-DOS Executive. Components included Calculator, Cardfile, Clipboard viewer, Control Panel, Paint, Reversi and Write. Windows 1.0 does not allow overlapping windows. Instead all windows are tiled. Only modal dialog boxes may appear over other windows. Microsoft sold as included Windows Development libraries with the C development environment, which included numerous windows samples. Windows 2.0 was released in December 1987, was more popular than its predecessor. It features several improvements to the user memory management. Windows 2.03 changed the OS from tiled windows to overlapping windows. The result of this change led to Apple Computer filing a suit against Microsoft alleging infringement on Apple's copyrights. Windows 2.0
Switched-mode power supply
A switched-mode power supply is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like other power supplies, an SMPS transfers power from a DC or AC source to DC loads, such as a personal computer, while converting voltage and current characteristics. Unlike a linear power supply, the pass transistor of a switching-mode supply continually switches between low-dissipation, full-on and full-off states, spends little time in the high dissipation transitions, which minimizes wasted energy. Ideally, a switched-mode power supply dissipates no power. Voltage regulation is achieved by varying the ratio of on-to-off time. In contrast, a linear power supply regulates the output voltage by continually dissipating power in the pass transistor; this higher power conversion efficiency is an important advantage of a switched-mode power supply. Switched-mode power supplies may be smaller and lighter than a linear supply due to the smaller transformer size and weight.
Switching regulators are used as replacements for linear regulators when higher efficiency, smaller size or lighter weight are required. They are, more complicated. 1836 Induction coils use switches to generate high voltages. 1910 An inductive discharge ignition system invented by Charles F. Kettering and his company Dayton Engineering Laboratories Company goes into production for Cadillac; the Kettering ignition system is a mechanically-switched version of a flyback boost converter. Variations of this ignition system were used in all non-diesel internal combustion engines until the 1960s when it began to be replaced first by solid-state electronically-switched versions capacitive discharge ignition systems. 1926 On 23 June, British inventor Philip Ray Coursey applies for a patent in his country and United States, for his "Electrical Condenser". The patent mentions furnaces, among other uses. C. 1932 Electromechanical relays are used to stabilize the voltage output of generators. See Voltage regulator#Electromechanical regulators.
C. 1936 Car radios used electromechanical vibrators to transform the 6 V battery supply to a suitable B+ voltage for the vacuum tubes. 1959 Transistor oscillation and rectifying converter power supply system U. S. Patent 3,040,271 is filed by Joseph E. Murphy and Francis J. Starzec, from General Motors Company c. 1967 Bob Widlar of Fairchild Semiconductor designs the µA723 IC voltage regulator. One of its applications is as a switched mode regulator. 1970 Tektronix starts using High-Efficiency Power Supply in its 7000-series oscilloscopes produced from about 1970 to 1995. 1972 HP-35, Hewlett-Packard's first pocket calculator, is introduced with transistor switching power supply for light-emitting diodes, timing, ROM, registers. 1973 Xerox uses switching power supplies in the Alto minicomputer 1977 Apple II is designed with a switching mode power supply. "Rod Holt was brought in as product engineer and there were several flaws in Apple II that were never publicized. One thing Holt has to his credit is that he created the switching power supply that allowed us to do a lightweight computer".
1980 The HP8662A 10 kHz – 1.28 GHz synthesized signal generator went with a switched mode power supply. A linear regulator provides the desired output voltage by dissipating excess power in ohmic losses. A linear regulator regulates either output voltage or current by dissipating the excess electric power in the form of heat, hence its maximum power efficiency is voltage-out/voltage-in since the volt difference is wasted. In contrast, a switched-mode power supply changes output voltage and current by switching ideally lossless storage elements, such as inductors and capacitors, between different electrical configurations. Ideal switching elements have no resistance when "on" and carry no current when "off", so converters with ideal components would operate with 100% efficiency. For example, if a DC source, an inductor, a switch, the corresponding electrical ground are placed in series and the switch is driven by a square wave, the peak-to-peak voltage of the waveform measured across the switch can exceed the input voltage from the DC source.
This is because the inductor responds to changes in current by inducing its own voltage to counter the change in current, this voltage adds to the source voltage while the switch is open. If a diode-and-capacitor combination is placed in parallel to the switch, the peak voltage can be stored in the capacitor, the capacitor can be used as a DC source with an output voltage greater than the DC voltage driving the circuit; this boost converter acts like a step-up transformer for DC signals. A buck–boost converter works in a similar manner, but yields an output voltage, opposite in polarity to the input voltage. Other buck circuits exist to boost the average output current with a reduction of voltage. In an SMPS, the output current flow depends on the input power signal, the storage elements and circuit topologies used, on the pattern used to drive the switching elements; the spectral density of these switching waveforms has energy concentrated at high frequencies. As such, switching transients and rip
IBM Personal Computer XT
The IBM Personal Computer XT shortened to the IBM XT, PC XT, or XT, is a version of the IBM PC with a built-in hard drive. It was released as IBM Machine Type number 5160 on March 8, 1983. Apart from the hard drive, it was the same as the original PC, with only minor improvements; the XT was intended as an enhanced IBM PC for business users. Floppy-only models would replace the original model 5150 PC. A corresponding 3270 PC featuring 3270 terminal emulation was released in October 1983. XT stands for eXtended Technology; the IBM Personal Computer XT came with 128 KB of RAM, a 360 KB double-sided 5¼ inch floppy disk drive, a 10 MB Seagate ST-412 hard drive with Xebec 1210 Modified Frequency Modulation controller, an Asynchronous Adapter, a 130-watt power supply. The motherboard had an Intel 8088 microprocessor running at 4.77 MHz, with a socket for an optional 8087 math coprocessor. IBM recognized soon after the IBM PC's release in 1981 that its five 8-bit "I/O channel" expansion slots were insufficient.
An internal IBM publication stated in October 1981 about the number that "In my opinion, it could be a problem", reporting that others within IBM advised swapping cards if necessary. Every PC required at least a display adapter card and a floppy disk controller card, leaving only three slots available for a parallel printer port card, a serial port card, memory expansion boards, a 3rd-party hard disk controller card, a second display adapter card, or possible other special adapter cards; when IBM announced a successor product to the PC in early 1983, initial speculations were that it would be a next-generation machine based on the Intel 8086 or include other advanced features. When the XT was unveiled however, there was mild disappointment that the new machine was an incremental improvement of the PC based on the same 8088 CPU and would in fact not replace it at all. A BYTE Magazine article commented that "DOS 2.0 is more revolutionary and advanced than the computer itself." A Seagate ST-412 hard disk was standard equipment, the XT was not offered in a floppy-only model for its first two years on the market, although the standard ribbon cable with two floppy connectors was still included.
The only way to purchase an XT with factory-installed dual floppy drives was if the user bought the optional 5161 expansion chassis and placed the hard disk in that, which in effect amounted to purchasing two hard disks as the 5161 came with one standard. Unlike many hard disk systems on microcomputers at the time, the XT was able to boot directly off the drive and did not require a boot floppy. Aside from the hard disk, a serial port card was standard equipment on the XT, all other cards being optional. By the end of 1983, the XT was neck-and-neck with the original PC for sales and IBM were selling every one that they made; the XT had eight slots. Two were behind the floppy drive, shorter than the original PC's slots; the other six fit into the same space as the original PC's five slots. Most PC cards would not fit into the two short slots, some would not fit into the six standard-length, but narrower, slots cards with double boards on them; the floppy and hard drive adapters, the serial port card, nearly always a display adapter board occupied slots.
The basic specification was soon upgraded to have 256 KB of RAM as standard. Expansion slots could be used for memory expansion. Available Video cards were the Monochrome Display Adapter and Color Graphics Adapter, with Enhanced Graphics Adapter and Professional Graphics Controller becoming available in 1984; the XT had a desktop case similar to that of the IBM PC. It weighed 32 pounds and was 19.5 inches wide by 16 inches deep by 5.5 inches high. The power supply of the original XT sold in the US was configured for 120 V AC only and could not be used with 240 V mains supplies. XTs with 240 V-compatible power supplies were sold in international markets. Both were rated at 130 watts; the operating system sold with the XT was PC DOS 2.0 or, by the time the XT was discontinued in early 1987, DOS 3.2. Like the original PC, the XT came with IBM BASIC in its ROM. Despite the lack of a cassette port on XTs, IBM's licensing agreement with Microsoft forced them to include BASIC on all their PCs, the BASICA program, included with DOS depended on the BASIC ROM.
The XT BIOS displayed a memory count during the POST, unlike the PC. The XT was discontinued in the spring of 1987, replaced by the PS/2 Model 30. XT motherboards came in two different versions; the original had 64 KB of 4164 RAM socketed on it with further sockets to support up to 256 KB and any more RAM had to be put on an expansion card, of which the AST Research Six Pak was the most widespread and popular. XTs produced in 1983-84 shipped in 1985, 256k; the second version had 256 KB socketed on it and could accommodate the entire 640 KB. XTs used 4164 DRAMs only for the first 256k and the remainder of system memory consisted of larger 41256 DRAMs; as a result, it took only 44 RAM chips to reach 640 kB versus the 80 chips needed on the original model XT. There were two or three revisions of the motherboard with minor differences between them; the first version incorporates a 470 ohm resistor to fix a race condition between the CPU and DMA controller which created the possibility of the system locking up.
In the spring o
A microprocessor is a computer processor that incorporates the functions of a central processing unit on a single integrated circuit, or at most a few integrated circuits. The microprocessor is a multipurpose, clock driven, register based, digital integrated circuit that accepts binary data as input, processes it according to instructions stored in its memory, provides results as output. Microprocessors contain sequential digital logic. Microprocessors operate on symbols represented in the binary number system; the integration of a whole CPU onto a single or a few integrated circuits reduced the cost of processing power. Integrated circuit processors are produced in large numbers by automated processes, resulting in a low unit price. Single-chip processors increase reliability because there are many fewer electrical connections that could fail; as microprocessor designs improve, the cost of manufacturing a chip stays the same according to Rock's law. Before microprocessors, small computers had been built using racks of circuit boards with many medium- and small-scale integrated circuits.
Microprocessors combined this into a few large-scale ICs. Continued increases in microprocessor capacity have since rendered other forms of computers completely obsolete, with one or more microprocessors used in everything from the smallest embedded systems and handheld devices to the largest mainframes and supercomputers; the complexity of an integrated circuit is bounded by physical limitations on the number of transistors that can be put onto one chip, the number of package terminations that can connect the processor to other parts of the system, the number of interconnections it is possible to make on the chip, the heat that the chip can dissipate. Advancing technology makes more powerful chips feasible to manufacture. A minimal hypothetical microprocessor might include only an arithmetic logic unit, a control logic section; the ALU performs addition and operations such as AND or OR. Each operation of the ALU sets one or more flags in a status register, which indicate the results of the last operation.
The control logic retrieves instruction codes from memory and initiates the sequence of operations required for the ALU to carry out the instruction. A single operation code might affect many individual data paths and other elements of the processor; as integrated circuit technology advanced, it was feasible to manufacture more and more complex processors on a single chip. The size of data objects became larger. Additional features were added to the processor architecture. Floating-point arithmetic, for example, was not available on 8-bit microprocessors, but had to be carried out in software. Integration of the floating point unit first as a separate integrated circuit and as part of the same microprocessor chip sped up floating point calculations. Physical limitations of integrated circuits made such practices as a bit slice approach necessary. Instead of processing all of a long word on one integrated circuit, multiple circuits in parallel processed subsets of each data word. While this required extra logic to handle, for example and overflow within each slice, the result was a system that could handle, for example, 32-bit words using integrated circuits with a capacity for only four bits each.
The ability to put large numbers of transistors on one chip makes it feasible to integrate memory on the same die as the processor. This CPU cache has the advantage of faster access than off-chip memory and increases the processing speed of the system for many applications. Processor clock frequency has increased more than external memory speed, so cache memory is necessary if the processor is not delayed by slower external memory. A microprocessor is a general-purpose entity. Several specialized processing devices have followed: A digital signal processor is specialized for signal processing. Graphics processing units are processors designed for realtime rendering of images. Other specialized units exist for video machine vision. Microcontrollers integrate a microprocessor with peripheral devices in embedded systems. Systems on chip integrate one or more microprocessor or microcontroller cores. Microprocessors can be selected for differing applications based on their word size, a measure of their complexity.
Longer word sizes allow each clock cycle of a processor to carry out more computation, but correspond to physically larger integrated circuit dies with higher standby and operating power consumption. 4, 8 or 12 bit processors are integrated into microcontrollers operating embedded systems. Where a system is expected to handle larger volumes of data or require a more flexible user interface, 16, 32 or 64 bit processors are used. An 8- or 16-bit processor may be selected over a 32-bit processor for system on a chip or microcontroller applications that require low-power electronics, or are part of a mixed-signal integrated circuit with noise-sensitive on-chip analog electronics such as high-resolution analog to digital converters, or both. Running 32-bit arithmetic on an 8-bit chip could end up using more power, as the chip must execute software with multiple instructions. Thousands of items that were traditionally not computer-related inc