In computing, floating-point arithmetic is arithmetic using formulaic representation of real numbers as an approximation so as to support a trade-off between range and precision. For this reason, floating-point computation is found in systems which include small and large real numbers, which require fast processing times. A number is, in general, represented to a fixed number of significant digits and scaled using an exponent in some fixed base. A number that can be represented is of the following form: significand × base exponent, where significand is an integer, base is an integer greater than or equal to two, exponent is an integer. For example: 1.2345 = 12345 ⏟ significand × 10 ⏟ base − 4 ⏞ exponent. The term floating point refers to the fact that a number's radix point can "float"; this position is indicated as the exponent component, thus the floating-point representation can be thought of as a kind of scientific notation. A floating-point system can be used to represent, with a fixed number of digits, numbers of different orders of magnitude: e.g. the distance between galaxies or the diameter of an atomic nucleus can be expressed with the same unit of length.
The result of this dynamic range is that the numbers that can be represented are not uniformly spaced. Over the years, a variety of floating-point representations have been used in computers. In 1985, the IEEE 754 Standard for Floating-Point Arithmetic was established, since the 1990s, the most encountered representations are those defined by the IEEE; the speed of floating-point operations measured in terms of FLOPS, is an important characteristic of a computer system for applications that involve intensive mathematical calculations. A floating-point unit is a part of a computer system specially designed to carry out operations on floating-point numbers. A number representation specifies some way of encoding a number as a string of digits. There are several mechanisms. In common mathematical notation, the digit string can be of any length, the location of the radix point is indicated by placing an explicit "point" character there. If the radix point is not specified the string implicitly represents an integer and the unstated radix point would be off the right-hand end of the string, next to the least significant digit.
In fixed-point systems, a position in the string is specified for the radix point. So a fixed-point scheme might be to use a string of 8 decimal digits with the decimal point in the middle, whereby "00012345" would represent 0001.2345. In scientific notation, the given number is scaled by a power of 10, so that it lies within a certain range—typically between 1 and 10, with the radix point appearing after the first digit; the scaling factor, as a power of ten, is indicated separately at the end of the number. For example, the orbital period of Jupiter's moon Io is 152,853.5047 seconds, a value that would be represented in standard-form scientific notation as 1.528535047×105 seconds. Floating-point representation is similar in concept to scientific notation. Logically, a floating-point number consists of: A signed digit string of a given length in a given base; this digit string is referred to mantissa, or coefficient. The length of the significand determines the precision; the radix point position is assumed always to be somewhere within the significand—often just after or just before the most significant digit, or to the right of the rightmost digit.
This article follows the convention that the radix point is set just after the most significant digit. A signed integer exponent. To derive the value of the floating-point number, the significand is multiplied by the base raised to the power of the exponent, equivalent to shifting the radix point from its implied position by a number of places equal to the value of the exponent—to the right if the exponent is positive or to the left if the exponent is negative. Using base-10 as an example, the number 152,853.5047, which has ten decimal digits of precision, is represented as the significand 1,528,535,047 together with 5 as the exponent. To determine the actual value, a decimal point is placed after the first digit of the significand and the result is multiplied by 105 to give 1.528535047×105, or 152,853.5047. In storing such a number, the base need not be stored, since it will be the same for the entire range of supported numbers, can thus be inferred. Symbolically, this final value is: s b p − 1 × b e, where s is the
The Motorola 68008 is an 8/16/32-bit microprocessor made by Motorola. It is a version of the Motorola 68000 with an 8-bit external data bus, as well as a smaller address bus; the original 68000 had a 16-bit data bus. These large buses made it hard to design a low-cost system based on the 68000. A 16-bit data bus required twice as many memory chips as an 8-bit one; the 68008, introduced in 1982, was designed to work with low-cost 8-bit memory systems. Because of its smaller data bus, it was only about half as fast as a 68000 of the same clock speed. However, it was still faster than competing 8-bit microprocessors, because the 68008 internally was based on 32-bit data registers and a 16-bit data bus. Except for its smaller data and address buses, the 68008 behaved identically to the 68000 and had the same internal organization and microarchitecture; the 68008 was an HMOS chip with about 70 000 transistors. There were two distinct versions of the chip; the original version came in a 48-pin dual in-line package and had a 20-bit address bus, allowing it to use up to 1 megabyte of memory.
A version came in a 52-pin plastic leaded chip carrier. Few computer systems used the 68008 as the main processor. However, the 68008 was popular in embedded systems. Motorola ended production of the 68008 in 1996. A small 68008 design M68000 8-/16-/32-Bit Microprocessors User's Manual, Ninth Edition Kiwi - an 68k Homebrew Computer
MOS Technology 6502
The MOS Technology 6502 is an 8-bit microprocessor, designed by a small team led by Chuck Peddle for MOS Technology. When it was introduced in 1975, the 6502 was, by a considerable margin, the least expensive microprocessor on the market, it sold for less than one-sixth the cost of competing designs from larger companies, such as Motorola and Intel, caused rapid decreases in pricing across the entire processor market. Along with the Zilog Z80, it sparked a series of projects that resulted in the home computer revolution of the early 1980s. Popular home video game consoles and computers, such as the Atari 2600, Atari 8-bit family, Apple II, Nintendo Entertainment System, Commodore 64, Atari Lynx, BBC Micro and others, used the 6502 or variations of the basic design. Soon after the 6502's introduction, MOS Technology was purchased outright by Commodore International, who continued to sell the microprocessor and licenses to other manufacturers. In the early days of the 6502, it was second-sourced by Rockwell and Synertek, licensed to other companies.
In its CMOS form, developed by the Western Design Center, the 6502 family continues to be used in embedded systems, with estimated production volumes in the hundreds of millions. The 6502 was designed by many of the same engineers that had designed the Motorola 6800 microprocessor family. Motorola started the 6800 microprocessor project in 1971 with Tom Bennett as the main architect; the chip layout began in late 1972, the first 6800 chips were fabricated in February 1974 and the full family was released in November 1974. John Buchanan was the designer of the 6800 chip and Rod Orgill, who did the 6501, assisted Buchanan with circuit analyses and chip layout. Bill Mensch joined Motorola in June 1971 after graduating from the University of Arizona, his first assignment was helping define the peripheral ICs for the 6800 family and he was the principal designer of the 6820 Peripheral Interface Adapter. Motorola's engineers could run digital simulations on an IBM 370-165 mainframe computer. Bennett hired Chuck Peddle in 1973 to do architectural support work on the 6800 family products in progress.
He contributed in many areas, including the design of the 6850 ACIA. Motorola's target customers were established electronics companies such as Hewlett-Packard, Tektronix, TRW, Chrysler. In May 1972, Motorola's engineers began visiting select customers and sharing the details of their proposed 8-bit microprocessor system with ROM, RAM, parallel and serial interfaces. In early 1974, they provided engineering samples of the chips so that customers could prototype their designs. Motorola's "total product family" strategy did not focus on the price of the microprocessor, but on reducing the customer's total design cost, they offered development software on a timeshare computer, the "EXORciser" debugging system, onsite training and field application engineer support. Both Intel and Motorola had announced a $360 price for a single microprocessor; the actual price for production quantities was much less. Motorola offered a design kit containing the 6800 with six support chips for $300. Peddle, who would accompany the sales people on customer visits, found that customers were put off by the high cost of the microprocessor chips.
To lower the price, the IC chip size would have to shrink so that more chips could be produced on each silicon wafer. This could be done by removing inessential features in the 6800 and using a newer fabrication technology, "depletion-mode" MOS transistors. Peddle and other team members started outlining the design of an improved feature, reduced size microprocessor. At that time, Motorola's new semiconductor fabrication facility in Austin, was having difficulty producing MOS chips and mid 1974 was the beginning of a year-long recession in the semiconductor industry. Many of the Mesa, employees were displeased with the upcoming relocation to Austin. Motorola Semiconductor Products Division's management was overwhelmed with problems and showed no interest in Peddle's low-cost microprocessor proposal. Chuck Peddle was frustrated with Motorola's management for missing this new opportunity. In a November 1975 interview, Motorola's Chairman, Robert Galvin, agreed, he said, "We did not choose the right leaders in the Semiconductor Products division."
The division was reorganized and the management replaced. New group vice-president John Welty said, "The semiconductor sales organization lost its sensitivity to customer needs and couldn't make speedy decisions."Peddle began looking for a source of funding for this new project and found a small semiconductor company in Pennsylvania. In August 1974, Chuck Peddle, Bill Mensch, Rod Orgill, Harry Bawcom, Ray Hirt, Terry Holdt and Wil Mathys left Motorola to join MOS Technology. Of the seventeen chip designers and layout people on the 6800 team, seven left. There were 30 to 40 application engineers and system engineers on the 6800 team; that December, Gary Daniels transferred into the 6800 microprocessor group. Tom Bennett did not want to leave the Phoenix area so Daniels took over the microprocessor development in Austin, his first project was a "depletion-mode" version of the 6800. The faster parts were available in July 1976; this was followed by the 6802 which added 128 bytes of an on-chip clock oscillator circuit.
MOS Technology was formed in 1969 by three executives from General Instrument, Mort Jaffe, Don McLaughlin, John Pavinen, to produce metal-oxide-semiconductor integrated circuits. Allen-Br
Central processing unit
A central processing unit called a central processor or main processor, is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logic and input/output operations specified by the instructions. The computer industry has used the term "central processing unit" at least since the early 1960s. Traditionally, the term "CPU" refers to a processor, more to its processing unit and control unit, distinguishing these core elements of a computer from external components such as main memory and I/O circuitry; the form and implementation of CPUs have changed over the course of their history, but their fundamental operation remains unchanged. Principal components of a CPU include the arithmetic logic unit that performs arithmetic and logic operations, processor registers that supply operands to the ALU and store the results of ALU operations and a control unit that orchestrates the fetching and execution of instructions by directing the coordinated operations of the ALU, registers and other components.
Most modern CPUs are microprocessors, meaning they are contained on a single integrated circuit chip. An IC that contains a CPU may contain memory, peripheral interfaces, other components of a computer; some computers employ a multi-core processor, a single chip containing two or more CPUs called "cores". Array processors or vector processors have multiple processors that operate in parallel, with no unit considered central. There exists the concept of virtual CPUs which are an abstraction of dynamical aggregated computational resources. Early computers such as the ENIAC had to be physically rewired to perform different tasks, which caused these machines to be called "fixed-program computers". Since the term "CPU" is defined as a device for software execution, the earliest devices that could rightly be called CPUs came with the advent of the stored-program computer; the idea of a stored-program computer had been present in the design of J. Presper Eckert and John William Mauchly's ENIAC, but was 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. It was the outline of a stored-program computer that would be completed in August 1949. EDVAC was designed to perform a certain number of instructions of various types; the programs written for EDVAC were to be stored in high-speed computer memory rather than specified by the physical wiring of the computer. This overcame a severe limitation of ENIAC, the considerable time and effort required to reconfigure the computer to perform a new task. With von Neumann's design, the program that EDVAC ran could be changed by changing the contents of the memory. EDVAC, was not the first stored-program computer. Early CPUs were custom designs used as part of a sometimes distinctive computer. However, this method of designing custom CPUs for a particular application has 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 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, sometimes in toys. While von Neumann is most credited with the design of the stored-program computer because of his design of EDVAC, the design became known as the von Neumann architecture, others before him, such as Konrad Zuse, had suggested and implemented similar ideas; the so-called Harvard architecture of the Harvard Mark I, completed before EDVAC used a stored-program design using punched paper tape rather than electronic memory. The key difference between the von Neumann and Harvard architectures is that the latter separates the storage and treatment of CPU instructions and data, while the former uses the same memory space for both.
Most modern CPUs are von Neumann in design, but CPUs with the Harvard architecture are seen as well in embedded applications. Relays and vacuum tubes were used as switching elements; 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 rarely. In the end, tube-based CPUs became dominant because the significant speed advantages afforded 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 common at this time, limited by the speed of the switching de
The Z80 CPU is an 8-bit based microprocessor. It was introduced by Zilog in 1976 as the startup company's first product; the Z80 was conceived by Federico Faggin in late 1974 and developed by him and his then-11 employees at Zilog from early 1975 until March 1976, when the first working samples were delivered. With the revenue from the Z80, the company built its own chip factories and grew to over a thousand employees over the following two years; the Zilog Z80 was a software-compatible extension and enhancement of the Intel 8080 and, like it, was aimed at embedded systems. According to the designers, the primary targets for the Z80 CPU were products like intelligent terminals, high end printers and advanced cash registers as well as telecom equipment, industrial robots and other kinds of automation equipment; the Z80 was introduced on the market in July 1976 and came to be used in general desktop computers using CP/M and other operating systems as well as in the home computers of the 1980s.
It was common in military applications, musical equipment, such as synthesizers, in the computerized coin operated video games of the late 1970s and early 1980, the arcade machines or video game arcade cabinets. The Z80 was one of the most used CPUs in the home computer market from the late 1970s to the mid-1980s. Zilog licensed the Z80 to the US-based Synertek and Mostek, which had helped them with initial production, as well as to a European second source manufacturer, SGS; the design was copied by several Japanese, East European and Soviet manufacturers. This won the Z80 acceptance in the world market since large companies like NEC, Toshiba and Hitachi started to manufacture the device. In recent decades Zilog has refocused on the ever-growing market for embedded systems and the most recent Z80-compatible microcontroller family, the pipelined 24-bit eZ80 with a linear 16 MB address range, has been introduced alongside the simpler Z180 and Z80 products; the Z80 came about when physicist Federico Faggin left Intel at the end of 1974 to found Zilog with Ralph Ungermann.
At Fairchild Semiconductor, at Intel, Faggin had been working on fundamental transistor and semiconductor manufacturing technology. He developed the basic design methodology used for memories and microprocessors at Intel and led the work on the Intel 4004, the 8080 and several other ICs. Masatoshi Shima, the principal logic and transistor level-designer of the 4004 and the 8080 under Faggin's supervision, joined the Zilog team. By March 1976, Zilog had developed the Z80 as well as an accompanying assembler based development system for its customers, by July 1976, this was formally launched onto the market. Early Z80s were manufactured by Synertek and Mostek, before Zilog had its own manufacturing factory ready, in late 1976; these companies were chosen because they could do the ion implantation needed to create the depletion-mode MOSFETs that the Z80 design used as load transistors in order to cope with a single 5 Volt power supply. Faggin designed the instruction set to be binary compatible with the Intel 8080 so that most 8080 code, notably the CP/M operating system and Intel's PL/M compiler for 8080, would run unmodified on the new Z80 CPU.
Masatoshi Shima designed most of the microarchitecture as well as the gate and transistor levels of the Z80 CPU, assisted by a small number of engineers and layout people. CEO Federico Faggin was heavily involved in the chip layout work, together with two dedicated layout people. Faggin worked 80 hours a week in order to meet the tight schedule given by the financial investors, according to himself; the Z80 offered many improvements over the 8080: An enhanced instruction set including single-bit addressing, shifts/rotates on memory and registers other than the accumulator, rotate instructions for BCD number strings in memory, program looping, program counter relative jumps, block copy, block input/output, byte search instructions. The Z80 had better support for signed 8 - and 16-bit arithmetics. New IX and IY index registers with instructions for direct base+offset addressing A better interrupt system A more automatic and general vectorized interrupt system, mode 2 intended for Zilog's line of counter/timers, DMA and communications controllers, as well as a fixed vector interrupt system, mode 1, for simple systems with minimal hardware.
A non maskable interrupt which can be used to respond to power down situations or other high priority events. Two separate register files, which could be switched, to speed up response to interrupts such as fast asynchronous event handlers or a multitasking dispatcher. Although they were not intended as extra registers for general code, they were used that way in some applications. Less hardware required for power supply, clock generation and interface to memory and I/O Single 5-volt power supply. Single-phase 5 V clock. A built-in DRAM refresh mechanism. Non-multiplexed buses. A special reset function which clears only the program counter so that a single Z80 CPU could be used in a
Gyruss is a fixed shooter arcade game designed by Yoshiki Okamoto and released by Konami in 1983. Gyruss was licensed to Centuri in the United States for dedicated machines, before Konami released their own self-distributed conversion kits for the game. Parker Brothers released contemporary ports for home systems. An enhanced version for the Family Computer Disk System was released in 1988, released to the North American Nintendo Entertainment System in early 1989; the gameplay is similar to that of Galaga in a tube shooter format, with the player's ship facing into the screen and able to move around the perimeter of an implicit circle. Stars come into view at the centre of the screen and fly outward, giving the impression of the player's ship moving through space. Gyruss is the last game Yoshiki Okamoto designed for Konami, after Time Pilot. Due to pay disputes, he was fired after the release of this game, soon joined Capcom, where he would write 1942 and produce Street Fighter II; the majority of enemies are spaceships.
They appear either from the centre of the screen or from one of the edges, move in swirling patterns. They can destroy it by contact, they hover near the centre of the screen after completing their deployment pattern, fly outwards and shoot at the player. If not destroyed by the player, the enemy ships fly away one by one. There are several other types of enemies: satellites and laser beam generators; these appear intermittently and soon disappear of their own accord. Satellites materialise in a group of three just in front of the player after the ordinary enemy ships have finished deployment, they shoot at the player. If the player has the basic weapon when the satellites appear the middle one will be a sun-like object. If destroyed, the player's ship gets a better weapon. If the better weapon has been gained all satellites are identical. Asteroids fly straight outwards from the centre of the screen at regular intervals, they can not be destroyed. Laser beam generators fly straight outwards from the centre of the screen.
They consist of two generator segments with a laser beam between them. The player's ship is destroyed by contact with either the beam; the player begins the game "2 WARPS TO NEPTUNE". After completing each level, the player is one warp closer to a planet; each time a planet is reached, the player's ship is seen flying towards it and a short bonus round is played, where the player can shoot enemy ships for bonus points without worrying about being destroyed by them. After reaching Neptune, the player is three warps from Uranus, progresses through Saturn, Jupiter and Earth, taking three warps to reach each planet. Stage one and every 10th stage thereafter the enemies do not fire on the player when entering the screen. After completing Earth's bonus stage, the player must travel through the fast "3 WARPS TO NEPTUNE" level before returning to the start of the game; the game's background music is an electronic, uptempo arrangement of J. S. Bach's Toccata and Fugue in D minor, BWV 565. Gyruss uses stereo sound, which according to the bonus material for Konami Arcade Classics, was achieved by utilizing discrete audio circuits.
Parker Brothers released contemporary ports for the Atari 2600, Atari 5200, Atari 8-bit family, ColecoVision, Commodore 64. Gyruss was remade for the Family Computer Disk System in Japan, the Nintendo Entertainment System in North America, released by Konami's subsidiary Ultra Games; these versions include several major revisions. The player can use a super phaser attack in addition to the normal guns, which cost energy There are additional enemies, including boss fights when the player reaches each planet Bonus stages after each planet's boss is defeated, for a chance to gain additional powerups There is a definite ending to the game. In the NES version, it's a brief text about the Universe being at peace. In the FDS version, there is a full ending sequence with credits. In addition to the satellites providing the usual double guns and bonus points, they can provide extra phasers, a smart bomb, an extra life Instead of the arcade's 24 stages, there are 39, including Venus and the Sun; the player can enter the Konami code at the title screen for extra lives, but it must be entered in reverse.
This version of the game is included in the Majesco Entertainment TV Game Konami Collector's Series: Arcade Advanced and was released for Japanese mobile phones in 2004. Gyruss is included in the compilation Konami 80's Arcade Gallery, released for both the arcade and PlayStation, it is part of Konami Collector's Series: Arcade Advanced for the Game Boy Advance. The Konami Live! Plug and Play PC controller includes an emulated Gyruss with an online scoreboard, as well as five other Konami titles. Dance Dance Revolution Ultramix 2 contains a remix of the Gyruss music as a playable song. A bootleg arcade version exists with the name Venus. Gyruss was cloned as a mini-game in the games Grand Theft Auto: San Andreas and Contra: Legacy of War. Gyruss at the Killer List of Videogames Gyruss for the Atari 8-bit family at Atari Mania Gyruss at the Arcade History database The Centuri Arcade Database Gyruss at c64-wiki.com
Joust (video game)
Joust is an arcade game developed by Williams Electronics and released in 1982. While not the first game to feature two-player cooperative play, Joust was more successful than its predecessors and popularized the concept; the player joystick to control a knight riding a flying ostrich. The objective is to progress through levels by defeating groups of enemy knights riding buzzards. John Newcomer led the development team, which included Bill Pfutzenreuter, Janice Woldenberg-Miller, Python Anghelo, Tim Murphy, John Kotlarik. Newcomer aimed to create a flying game with cooperative two-player gameplay, but wanted to avoid a space theme, popular at the time; the game was well received in arcades and by critics, who praised the gameplay, the mechanics of which influenced titles by other developers. Joust was followed by a sequel four years and was ported to numerous home and portable platforms; the player controls a yellow knight riding a flying ostrich or stork, from a third-person perspective. Using the two-way directional joystick and the button for flapping the ostrich's wings, the player flies the knight amidst the floating rock platforms and above pools of lava.
The rate at which the player presses the button causes the ostrich to fly upward, hover, or descend. Players navigate the knight to collide with enemies. If the protagonist's jousting lance is higher than that of the enemy, the villain is defeated and vice versa. A collision of equal height results in the two knights bouncing off each other. A defeated enemy will turn into an egg that falls toward the bottom of the screen, which a player can collect for points. An egg that sits on a platform long enough will hatch into a new knight; the objective is to defeat groups of enemy knights riding buzzards that populate each level, referred to as a "wave". Upon completing a wave, a subsequent, more challenging wave begins; the game features three types of enemy knights—Bounder and Shadow Lord—that are worth different quantities of points. An indestructible pterodactyl appears after a predetermined time frame to hunt the heroes, as an incentive to complete the wave, it must be lanced in the center of the mouth when open to eliminate it for 1000 points.
There is another indestructible enemy, the Lava Troll, never seen except for its fire. When the player gets too low near the flames, a floating hand will grasp any knight/steed who approaches the lava pools, will drag them to a fiery demise unless the knight/steed breaks free by flapping out of the grasp. A second player, controlling a blue knight on a stork, can join the game; the two players can either cooperatively complete the waves or attack each other while competitively defeating enemies. Joust was developed with John Newcomer as the lead designer. Programmer Bill Pfutzenrueter and artists Janice Woldenberg-Miller and Python Anghelo assisted him. Tim Murphy and John Kotlarik handled the audio design; the game features amplified monaural raster graphics on a 19-inch color CRT monitor. Like other Williams arcade games, Joust was programmed in assembly language. A pack of three AA batteries provide power to save the game's settings and high scores when the machine is unplugged from an electrical outlet.
The cabinet artwork, by Anghelo, is stenciled on a wooden frame. Anghelo designed artwork for promotional materials. Following the success of the 1981 title Defender, Williams searched for new creative staff. Believing video games to be the future of entertainment, Newcomer left his job as a toy designer to work at the company who hired him to create game ideas as support for development staff. After a few days, he generated a list of ideas that included game ideas for The War of the Worlds and Joust, Newcomer's top two choices. Technical specifications dictated the selection. A development team was formed. Newcomer conceived Joust as a "flying game" with cooperative two-player gameplay. To that end, Newcomer made a list of things that could fly: machines and fictional characters. After evaluating the positive and negative of each idea, he chose birds, believing that they would have a wide appeal. Newcomer felt that birds were a good fit as he was familiar with fantasy and science fiction media featuring birds.
To further increase his understanding, Newcomer went to the library to study mythology. He felt; the first choice was an eagle. Instead, Newcomer chose an ostrich because he thought a flying ostrich was more believable than a running eagle. To differentiate between the first and second player characters, the developers picked a stork, believing the proportions were similar to an ostrich while the color difference would avoid confusion among players. Newcomer chose vultures as the main enemies, believ