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IBM 7080
The IBM 7080 was a variable word length BCD transistor computer in the IBM 700/7000 series commercial architecture line, introduced in August 1961, that provided an upgrade path from the vacuum tube IBM 705 computer. The 7080 weighed about . After the introduction of the IBM 7070, in June 1960, as an upgrade path for both the IBM 650 and IBM 705 computers, IBM realized that it was so incompatible with the 705 that few users of that system wanted to upgrade to the 7070. That prompted the development of the 7080, which was fully compatible with all models of the 705 and added many improvements. IBM 705 compatibility modes For backward compatibility with the IBM 705 the machine had two switches on the operator's control panel, ''705 I-II'' and ''40K memory'', that selected the mode the machine started in. *705 I mode — 20,000 characters (''705 I-II'' On, ''40K memory'' Off) **Indirect addressing is disabled **Communication channels are disabled *705 II mode — 40,000 characte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Word Length (computer Hardware)
In computing, a word is the natural unit of data used by a particular processor design. A word is a fixed-sized datum handled as a unit by the instruction set or the hardware of the processor. The number of bits or digits in a word (the ''word size'', ''word width'', or ''word length'') is an important characteristic of any specific processor design or computer architecture. The size of a word is reflected in many aspects of a computer's structure and operation; the majority of the registers in a processor are usually word-sized and the largest datum that can be transferred to and from the working memory in a single operation is a word in many (not all) architectures. The largest possible address size, used to designate a location in memory, is typically a hardware word (here, "hardware word" means the full-sized natural word of the processor, as opposed to any other definition used). Documentation for older computers with fixed word size commonly states memory sizes in words ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary-coded Decimal
In computing and electronic systems, binary-coded decimal (BCD) is a class of binary encodings of decimal numbers where each digit is represented by a fixed number of bits, usually four or eight. Sometimes, special bit patterns are used for a sign or other indications (e.g. error or overflow). In byte-oriented systems (i.e. most modern computers), the term ''unpacked'' BCD usually implies a full byte for each digit (often including a sign), whereas ''packed'' BCD typically encodes two digits within a single byte by taking advantage of the fact that four bits are enough to represent the range 0 to 9. The precise 4-bit encoding, however, may vary for technical reasons (e.g. Excess-3). The ten states representing a BCD digit are sometimes called '' tetrades'' (for the nibble typically needed to hold them is also known as a tetrade) while the unused, don't care-states are named , ''pseudo-decimals'' or ''pseudo-decimal digits''. BCD's main virtue, in comparison to binary posit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transistor Computer
A transistor computer, now often called a second-generation computer, is a computer which uses discrete transistors instead of vacuum tubes. The first generation of electronic computers used vacuum tubes, which generated large amounts of heat, were bulky and unreliable. A second-generation computer, through the late 1950s and 1960s featured circuit boards filled with individual transistors and magnetic core memory. These machines remained the mainstream design into the late 1960s, when integrated circuits started appearing and led to the third-generation computer. History The University of Manchester's experimental Transistor Computer was first operational in November 1953 and it is widely believed to be the first transistor computer to come into operation anywhere in the world. There were two versions of the Transistor Computer, the prototype, operational in 1953, and the full-size version, commissioned in April 1955. The 1953 machine had 92 point-contact transistors and 550 di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 700/7000 Series
The IBM 700/7000 series is a series of large-scale (Mainframe computer, mainframe) computer systems that were made by IBM through the 1950s and early 1960s. The series includes several different, incompatible processor architectures. The 700s use vacuum-tube logic and were made obsolete by the introduction of the transistor computer, transistorized 7000s. The 7000s, in turn, were eventually replaced with System/360, which was announced in 1964. However the 360/65, the first 360 powerful enough to replace 7000s, did not become available until November 1965. Early problems with OS/360 and the high cost of converting software kept many 7000s in service for years afterward. Architectures The IBM 700/7000 series has six completely different ways of storing data and instructions: *First scientific (36/18-bit words): IBM 701, 701 (Defense Calculator) *Later scientific (36-bit words, hardware floating-point): IBM 704, 704, IBM 709, 709, IBM 7040, 7040, IBM 7044, 7044, IBM 7090, 7090, I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Tube
A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type known as a thermionic tube or thermionic valve utilizes thermionic emission of electrons from a hot cathode for fundamental electronic functions such as signal amplifier, amplification and current rectifier, rectification. Non-thermionic types such as a vacuum phototube, however, achieve electron emission through the photoelectric effect, and are used for such purposes as the detection of light intensities. In both types, the electrons are accelerated from the cathode to the anode by the electric field in the tube. The simplest vacuum tube, the diode (i.e. Fleming valve), invented in 1904 by John Ambrose Fleming, contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through the device—fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 705
The IBM 700/7000 series is a series of large-scale (mainframe) computer systems that were made by IBM through the 1950s and early 1960s. The series includes several different, incompatible processor architectures. The 700s use vacuum-tube logic and were made obsolete by the introduction of the transistorized 7000s. The 7000s, in turn, were eventually replaced with System/360, which was announced in 1964. However the 360/65, the first 360 powerful enough to replace 7000s, did not become available until November 1965. Early problems with OS/360 and the high cost of converting software kept many 7000s in service for years afterward. Architectures The IBM 700/7000 series has six completely different ways of storing data and instructions: *First scientific (36/18- bit words): 701 (Defense Calculator) *Later scientific (36-bit words, hardware floating-point): 704, 709, 7040, 7044, 7090, 7094 *Commercial (variable-length character strings): 702, 705, 7080 * 1400 series ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 7070
IBM 7070 was a decimal-architecture intermediate data-processing system that was introduced by IBM in 1958. It was part of the IBM 700/7000 series, and was based on discrete transistors rather than the vacuum tubes of the 1950s. It was the company's first transistorized stored-program computer. The 7070 was expected to be a "common successor to at least the 650 and the 705". The 7070 was not designed to be instruction set compatible with the 650, as the latter had a second jump address in every instruction to allow optimal use of the drum, something unnecessary and wasteful in a computer with random-access core memory. As a result, a simulator was needed to run old programs. The 7070 was also marketed as an IBM 705 upgrade, but failed miserably due to its incompatibilities, including an inability to fully represent the 705 character set; forcing IBM to quickly introduce the IBM 7080 as a "transistorized IBM 705" that was fully compatible. The 7070 series stored data in words con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 650
The IBM 650 Magnetic Drum Data-Processing Machine is an early digital computer produced by IBM in the mid-1950s. It was the first mass produced computer in the world. Almost 2,000 systems were produced, the last in 1962, and it was the first computer to make a meaningful profit. The first one was installed in late 1954 and it was the most-popular computer of the 1950s. The 650 was marketed to business, scientific and engineering users as a general-purpose version of the IBM 701 and IBM 702 computers which were for scientific and business purposes respectively. It was also marketed to users of unit record equipment, punched card machines who were upgrading from Unit record equipment#Calculating, calculating punches, such as the IBM 604, to computers. Because of its relatively low cost and ease of Computer programming, programming, the 650 was used to pioneer a wide variety of applications, from modeling submarine crew performance to teaching high school and college students c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backward Compatibility
Backward compatibility (sometimes known as backwards compatibility) is a property of an operating system, product, or technology that allows for interoperability with an older legacy system, or with input designed for such a system, especially in telecommunications and computing. Modifying a system in a way that does not allow backward compatibility is sometimes called " breaking" backward compatibility. A complementary concept is forward compatibility. A design that is forward-compatible usually has a roadmap for compatibility with future standards and products. A related term from programming jargon is hysterical reasons or hysterical raisins (near-homophones for "historical reasons"), as the purpose of some software features may be solely to support older hardware or software versions. Usage In hardware A simple example of both backward and forward compatibility is the introduction of FM radio in stereo. FM radio was initially mono, with only one audio channel represented ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Punched Card Input/output
A computer punched card reader or just computer card reader is a computer input device used to read computer programs in either source or executable form and data from punched cards. A computer card punch is a computer output device that punches holes in cards. Sometimes computer punch card readers were combined with computer card punches and, later, other devices to form multifunction machines. It is a input device and also an output device. Most early computers, such as the ENIAC, and the IBM NORC, provided for punched card input/output. Card readers and punches, either connected to computers or in off-line card to/from magnetic tape configurations, were ubiquitous through the mid-1970s. Punched cards had been in use since the 1890s; their technology was mature and reliable. Card readers and punches developed for punched card machines were readily adaptable for computer use. Businesses were familiar with storing data on punched cards and keypunch machines were widely employe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 727
The IBM 727 Magnetic Tape Unit was announced for the IBM 701 and IBM 702 on September 25, 1953. It became IBM's standard tape drive for their early vacuum-tube era computer systems. Later vacuum-tube machines and first-generation transistor computers used the IBM 729-series tape drive. The 727 was withdrawn on May 12, 1971. The tape had seven parallel tracks – six for data and one to maintain parity. Tapes with character data ( BCD) were recorded in even parity. Binary tapes used odd parity. Aluminum strips were glued several feet from the ends of the tape to serve as logical beginning and end of tape markers. Write protection Write protection is any physical mechanism that prevents writing, modifying, or erasing data on a device. Most commercial software, audio and video on writeable media is write-protected when distributed. Examples * IBM -inch magnetic tape r ... was provided by a removable plastic ring in the back of the tape reel. References 727 Tape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
