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The Bendix G-15 computer was introduced in 1956 by the Bendix Corporation, Computer Division, Los Angeles, California. A computer is a Machine that manipulates data according to a list of instructions. Year 1956 ( MCMLVI) was a Leap year starting on Sunday (link will display full calendar of the Gregorian calendar. The Bendix Corporation was an American manufacturing and engineering company which during various times in its 60 year existence made brake systems aeronautical hydraulics Los Angeles (lɑˈsændʒələs los ˈaŋxeles in Spanish) is the largest City in the state of California and the American West It was about 5 by 3 by 3 ft (1. A foot (plural feet or foot; symbol or abbreviation ft or sometimes &prime – the prime symbol) is a non-SI unit 5m by 1m by 1m) and weighed about 950 lb (450 kg). The pound or pound-mass (abbreviation lb, lbm, or sometimes in the United States #) is a unit of Mass The base system, without peripherals, cost $49,500. A working model cost around $60,000. It could also be rented for $1,485 per month. It was meant for scientific and industrial markets. The series was gradually discontinued when Control Data Corporation took over the Bendix computer division in 1963. Control Data Corporation (CDC, was one of the pioneering Supercomputer firms Year 1963 ( MCMLXIII) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar.

The chief designer of the G-15 was Harry Huskey, who had worked with Alan Turing on the ACE in the United Kingdom and on the SWAC in the 1950s. Harry Douglas Huskey (born January 19, 1916) is an American computer designer pioneer Alan Mathison Turing, OBE, FRS (ˈt(jʊ(ərɪŋ (23 June 1912 &ndash 7 June 1954 was an English Mathematician The Automatic Computing Engine ( ACE) was an early Electronic stored-program Computer design produced by Alan Turing at the invitation of John The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located The SWAC ( Standards Western Automatic Computer) was an early electronic digital Computer built in 1950 by the U The 1950s Decade refers to the years of 1950 to 1959 inclusive He made most of the design while working as a professor at Berkeley, and other universities. The University of California Berkeley (also referred to as Cal, Berkeley and UC Berkeley) is a major research university located in Berkeley David C. Evans was one of the Bendix engineers on the G-15 project. David C Evans (1924–1998 was the founder of the Computer science department at University of Utah and co-founder (with Ivan Sutherland) of Evans He would later become famous for his work in computer graphics and for starting up Evans & Sutherland with Ivan Sutherland. Evans & Sutherland ( is a Computer firm involved in the Computer graphics field Ivan Edward Sutherland (born 1938 in Hastings, Nebraska) is an American Computer scientist and Internet pioneer

Contents

Architecture

The G-15 was a serial-architecture machine, one of several inspired by the ACE. A serial computer is typified by internally operating on one Bit or digit for each clock cycle. The Automatic Computing Engine ( ACE) was an early Electronic stored-program Computer design produced by Alan Turing at the invitation of John It used a magnetic drum to simulate the recirculating delay line memory of other serial designs. Drum memory is a magnetic Data storage device and was an early form of Computer memory widely used in the 1950s and into the 1960s invented by Gustav Tauschek Each track had a set of read and write heads; as soon as a bit was read off a track, it was re-written on the same track a certain distance away. The length of delay, and thus the number of words on a track, was determined by the spacing of the read and write heads, the delay corresponding to the time required for a section of the drum to travel from the write head to the corresponding read head. In Computing, " word " is a term for the natural unit of data used by a particular computer design Under normal operation, data was written back without change, but this data flow could be intercepted at any time, allowing the machine to update sections of a track as needed.

This arrangement allowed the designers to create "delay lines" of any desired length. In addition to the twenty "long lines" of 108 words each, there were several short lines of 4 words each. These short lines recycled at 27 times the rate of the long lines, allowing fast access to frequently needed data. Even the machine's accumulators were implemented as drum lines: three double-word and one single-word accumulator. In Computer architecture, a processor register is a small amount of storage available on the CPU whose contents can be accessed more quickly than storage This use of the drum rather than flip-flops for the registers helped to reduce tube count.

A consequence of this design was that, unlike other computers with magnetic drums, the G-15 did not retain its memory when it was shut off. The only permanent tracks were two timing tracks recorded on the drum at the factory. The second track was a backup as the tracks were liable to erasure if one of their amplifier tubes shorted.

The serial nature of the G-15's memory was carried over into the design of its arithmetic and control circuits. The adders worked on one digit at a time, and even the instruction word was designed to minimize the number of bits in an instruction that needed to be retained in flip-flops.

The G-15 had 180 vacuum tube packs and 300 germanium diodes. This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. Dioden2jpg|thumb|right|150px|Figure 2 Various semiconductor diodes [1] It had a total about about 450 tubes (mostly dual triodes). [2] Its magnetic drum memory held 2,160 words of twenty-nine bits. Drum memory is a magnetic Data storage device and was an early form of Computer memory widely used in the 1950s and into the 1960s invented by Gustav Tauschek In Computing, " word " is a term for the natural unit of data used by a particular computer design A bit is a binary digit, taking a value of either 0 or 1 Binary digits are a basic unit of Information storage and communication Average memory access time was 14. 5 milliseconds, but its instruction addressing architecture could reduce this dramatically for well-written programs. A millisecond (from Milli- and Second; abbreviation ms is one thousandth of a Second. Its addition time was 270 microseconds (not counting memory access time). Single-precision multiplication took 2,439 microseconds and double-precision multiplication took 16,700 microseconds. In Computing, single precision is a Computer numbering format that occupies one storage location in computer memory at a given address In Computing, double precision is a Computer numbering format that occupies two adjacent storage locations in computer memory

Peripherals

One of the G-15's primary output devices was the typewriter with an output speed of about 10 characters per second for numbers (and lower-case hex characters u-z) and about three characters per second for alphabetical characters. The machine's limited storage precluded much output of anything but numbers; occasionally, paper forms with pre-printed fields/labels were inserted into the typewriter. A faster typewriter unit was also available.

The high-speed photoelectric paper tape reader (250 'hexadecimal' digits per second on five-channel paper tape for the PR-1; 400 characters from 5-8 channel tape for the PR-2) read programs (and occasionally saved data) from tapes that were often mounted in cartridges for easy loading/unloading. Not unlike magnetic tape, the paper tape data was blocked into runs of 108 words or less since that was the maximum read size. A cartridge could contain many multiple blocks, up to 2500 words (~10 kilobytes). A kilobyte (derived from the SI prefix Kilo -, meaning 1000 is a unit of Information or Computer storage equal to either 1024

While the G-15 had an optional high-speed paper tape punch (the PTP-1 at 60 digits/second) for output, the standard punch operated at 17 hex characters/second (510 bytes/minute). A byte (pronounced "bite" baɪt is the basic unit of measurement of information storage in Computer science.

Optionally, the AN-1 "Universal Code Accessory" included the "35-4" Friden Flexowriter and HSR-8 paper tape reader and HSP-8 paper tape punch. The Friden Flexowriter, or flexowriter as on its nameplate was a Teleprinter, a heavy duty electric typewriter capable of being driven not only by a human typing The mechanical reader and punch could process paper tapes up to eight channels wide at 110 characters/second.

The CA-1 "Punched Card Coupler" could connect one or two IBM 026 card punches (which were more often used as manual devices) to read cards at 17 columns/second (ca. 12 full cards/minute) or punch cards at 11 columns/second (ca. eight full cards/minute). Partially-full cards were processed more quickly with an 80 column/second skip speed). The more expensive CA-2 Punched Card Coupler read and punched cards at a 100 card/minute rate.

The PA-3 pen plotter ran at one inch/second with 200 increments/inch on a paper roll one foot wide by 100 feet long. The optional retractable pen holder eliminated "retrace lines".

The MTA-2 could interface up to four drives for half-inch Mylar magnetic tapes which could store as many as 300,000 words (in blocks no longer than 108 words). The read/write rate was 430 hexadecimal digits/second; the bidirectional search speed was 2500 characters/second.

The DA-1 differential analyzer facilitated solution of differential equations. It contained 108 integrators and 108 constant multipliers, sporting 34 updates/second.

Software

A problem peculiar to machines with serial memory is the latency of the storage medium: instructions and data are not always immediately available and, in the worst case, one must wait for the complete recirculation of a delay line to obtain data from a given memory address. The problem was addressed in the G-15 by what the Bendix literature called "minimum-access coding. " Each instruction carried with it the address of the next instruction to be executed, allowing the programmer to arrange instructions such that when one instruction completed, the next instruction was about to appear under the read head for its line. Data could be staggered in a similar manner. To aid this process, the coding sheets included a table containing numbers of all addresses; the programmer would cross off each address as it was used.

A symbolic assembler, similar to the IBM 650's SOAP, was introduced in the late 1950's and included routines for minimum-access coding. The IBM 650 ( photo was one of IBM ’s early Computers and the world’s first mass-produced ( photo computer Other programming aids included a supervisor program, Intercom (a floating-point interpretive system ) and ALGO, an algebraic language designed from the 1958 Preliminary Report of the ALGOL committee. ALGO is an Algebraic Programming language developed between 1959 and 1961 for the Bendix G-15 Computer. ALGOL 58, originally known as IAL, is one of the family of ALGOL computer Programming languages It was an early compromise design soon superseded by Algol (β Per / Beta Persei known colloquially as the Demon Star, is a bright Star in the Constellation Perseus. Users also developed their own tools, and a variant of Intercom suited to the needs of civil engineers is said to have circulated.

Floating point was implemented in software. The 'Intercom' series of languages provided an easier to program virtual machine that operated in floating point. Instructions to Intercom 500, 550, and 1000 were numerical, six or seven digits in length. Instructions were stored sequentially; the beauty was convenience, not speed. Intercom 1000 even had an optional double-precision version.

Significance

The G-15 is sometimes described as the first personal computer, because it had the interpretive system Intercom. A personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated The title is disputed by other machines such as the LINC and the PDP-8 and some maintain that only microcomputers such as those which appeared in the 1970s can be called personal computers. The LINC (Laboratory Instrument Computer was a 12-bit, 2048-word Computer. The PDP-8 was the first successful commercial Minicomputer, produced by Digital Equipment Corporation (DEC in the 1960s Nevertheless, the machine's low acquisition and operating costs (and the fact that it did not require a dedicated operator) meant that organizations could allow users complete access to the machine.

Over 400 G-15s were manufactured. About 300 G-15s were installed in the United States and a few were sold in other countries such as Australia and Canada. The United States of America —commonly referred to as the For a topic outline on this subject see List of basic Australia topics. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page The machine found a niche in civil engineering, where it was used to solve cut and fill problems. Civil engineering is a professional engineering discipline that deals with the design construction and maintenance of the physical and naturally built Cut and Fill in earthmoving is the process of constructing a Railway, Road or Canal whereby the amount of material from cuts roughly matches Some have survived and have made their way to computer museums or science and technology museums around the world.

Huskey himself received one of the last production G15's, fitted with a gold-plated front panel.

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