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40-518: Development on the project began in March 1946 at Northrop Corporation with the goal of producing a subsonic cruise missile designated "MX-775", which came to be called the Snark. Northrop's parameters for this project were to create a guidance system that would allow a missile to hit a target at a distance of up to 5,000 miles (8,000 km) with a precision that would be 200 yards (180 m) better than

80-642: A "Northrop Corporation" located in El Segundo, California , which produced several successful designs, including the Northrop Gamma and Northrop Delta . However, labor difficulties led to the dissolution of the corporation by Douglas in 1937, and the plant became the El Segundo Division of Douglas Aircraft . Northrop still sought his own company, and so in 1939 he established the "Northrop Corporation" in nearby Hawthorne, California ,

120-432: A 100-card-per-minute rate. The PA-3 pen plotter runs at 1 inch per second with 200 increments per inch on a paper roll 1 foot wide by 100 feet long. The optional retractable pen-holder eliminates "retrace lines". The MTA-2 can interface up to four drives for half-inch Mylar magnetic tapes, which can store as many as 300,000 words (in blocks no longer than 108 words). The read/write rate is 430 hexadecimal digits per second;

160-551: A long and fruitless lawsuit between the two companies. Northrop continued to build much of the F-18 fuselage and other systems after this period, but also returned to the original F-5 design with yet another new engine to produce the F-20 Tigershark as a low-cost aircraft. This garnered little interest in the market, and the project was dropped. In 1985, Northrop bought northrop.com, the sixth .com domain created. Based on

200-436: A niche in civil engineering , where it was used to solve cut and fill problems. Some have survived and have made their way to computer museums or science and technology museums around the world. Huskey received one of the last production G15s, fitted with a gold-plated front panel. This was the first computer that Ken Thompson ever used. A Bendix G-15 was used at Fremont High School (Oakland Unified School District) in

240-757: A site located by co-founder Moye Stephens . The corporation ranked 100th among United States corporations in the value of World War II military production contracts. It was there that the P-61 Black Widow night fighter , the B-35 and YB-49 experimental flying wing bombers, the F-89 Scorpion interceptor , the SM-62 Snark intercontinental cruise missile , and the F-5 Freedom Fighter economical jet fighter (and its derivative,

280-480: 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 (to the extent of leveraging another one-word drum line used exclusively for generating address timing signals). The G-15 has 180 vacuum tube packs and 3000 germanium diodes . It has a total of about 450 tubes (mostly dual triodes). Its magnetic drum memory holds 2,160 words of twenty-nine bits . Average memory access time

320-767: Is 14.5 milliseconds , but its instruction addressing architecture can reduce this dramatically for well-written programs. Its addition time is 270 microseconds (not counting memory access time). Single-precision multiplication takes 2,439 microseconds and double-precision multiplication takes 16,700 microseconds. One of the G-15's primary output devices is the typewriter with an output speed of about 10 characters per second for numbers (and lower-case hexadecimal characters u-z) and about three characters per second for alphabetical characters. The machine's limited storage precludes much output of anything but numbers; occasionally, paper forms with pre-printed fields or labels were inserted into

360-608: Is a computer introduced in 1956 by the Bendix Corporation , Computer Division, Los Angeles , California. It is about 5 by 3 by 3 feet (1.52 m × 0.91 m × 0.91 m) and weighs about 966 pounds (438 kg). The G-15 has a drum memory of 2,160 29-bit words, along with 20 words used for special purposes and rapid-access storage. The base system, without peripherals, cost $ 49,500. A working model cost around $ 60,000 (equivalent to $ 672,411 in 2023). It could also be rented for $ 1,485 per month. It

400-455: Is about to appear under the read head for its line. Data can be staggered in a similar manner. To aid this process, the coding sheets include a table containing numbers of all addresses; the programmer can cross off each address as it is used. Bendix has an operating system of the same name. A symbolic assembler, similar to the IBM 650 's Symbolic Optimal Assembly Program (SOAP), was introduced in

440-430: Is implemented in software. The "Intercom" series of languages provide an easier to program virtual machine that operates in floating point. Instructions to Intercom 500, 550, and 1000 are numerical, six or seven digits in length. Instructions are stored sequentially; the beauty is convenience, not speed. Intercom 1000 even has an optional double-precision version. As mentioned above the machine uses hexadecimal numbers, but

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480-687: Is known for its development of the flying wing design, most successfully the B-2 Spirit stealth bomber. Jack Northrop founded 3 companies using his name. The first was the Avion Corporation in 1928, which was absorbed in 1929 by the United Aircraft and Transport Corporation as a subsidiary named "Northrop Aircraft Corporation" (and later became part of Boeing ). The parent company moved its operations to Kansas in 1931, and so Jack, along with Donald Douglas , established

520-634: Is now part of the collection at the Computer History Museum in Mountain View, California. Ultimately, the MADDIDA was never used in weaponry. Northrop ended up using a different analog computing system to guide the Snark missile, a system that was so dubious that many missiles were lost. A missile launched in 1956 went so far off course that it landed in north-eastern Brazil and was not found until 1983. Many of those connected with

560-1109: Is the maximum read size. A cartridge can contain many multiple blocks, up to 2500 words (~10 kilobytes ). While there is an optional high-speed paper tape punch (the PTP-1 at 60 digits per second) for output, the standard punch operates at 17 hex characters per second (510 bytes per minute). 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 mechanical reader and punch can process paper tapes up to eight channels wide at 110 characters per second. The CA-1 "Punched Card Coupler" can connect one or two IBM 026 card punches (which were more often used as manual devices) to read cards at 17 columns per second (approximately 12 full cards per minute) or punch cards at 11 columns per second (approximately 8 full cards per minute). Partially full cards were processed more quickly with an 80-column-per-second skip speed). The more expensive CA-2 Punched Card Coupler reads and punches cards at

600-737: The Computer Research Corporation (CRC), which in 1953 was sold to NCR . Max Palevsky , who later worked with the MADDIDA duplication team at Northrop, drew influence from the MADDIDA's design in his work in 1952–1956 building the Bendix G-15 , an early personal computer, for the Bendix Corporation . In March 1957, Palevsky begin work at Packard Bell , at a new affiliate of the company he started called Packard Bell Computer Corp. Palevsky continued gaining commercial support for digital computing, allowing design advancement to continue. He retired as Director and chairman of

640-416: The analog delay line implementation in other serial designs. Each track has a set of read and write heads; as soon as a bit was read off a track, it is re-written on the same track a certain distance away. The length of delay, and thus the number of words on a track, is 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

680-574: The 1964-65 school year for the senior seminar math class. Students were taught the fundamentals of programming. One such exercise was the calculation of a square root using the method of Newtonian approximation. A Bendix G-15 was still in use for the UC Berkeley extension summer class in programming, at Oakland Technical High School, in 1970. A Bendix G-15 was used at the Summer Science Program , at least in 1962 and 1963. One of

720-487: The 1970s, can be called personal computers. Nevertheless, the machine's low acquisition and operating costs, and the fact that it does 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 machine found

760-486: The German "vengeance" weapons V1 and V2 . However, the MADDIDA was never used in weaponry, and Northrop ultimately used a different analog computer as the guidance system for the Snark missile. Part of the project parameters involved developing the first digital data analyzer (DIDA). Physicist Floyd Steele , who had reportedly in 1946 already demonstrated a working DIDA before the press in 1946 in his Los Angeles home,

800-900: The P-600, and eventually the YF-17 Cobra , which lost the competition to the General Dynamics F-16 Fighting Falcon . Nevertheless, the YF-17 Cobra was modified with help from McDonnell Douglas to become the McDonnell Douglas F/A-18 Hornet in order to fill a similar lightweight design competition for the US Navy . Northrop intended to sell a de-navalized version as the F-18L, but the basic F-18A continued to outsell it, leading to

840-405: The bidirectional search speed is 2500 characters per second. The DA-1 differential analyzer facilitates solution of differential equations. It contains 108 integrators and 108 constant multipliers, sporting 34 updates per second. 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,

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880-514: The executive committee of Xerox in May 1972. While Xerox would eventually drop personal computing, the Xerox prototypes would influence Steve Jobs and Steve Wozniak in their 1979 tour of the Xerox facility Northrop Corporation Northrop Corporation was an American aircraft manufacturer from its formation in 1939 until its 1994 merger with Grumman to form Northrop Grumman . The company

920-556: The experimentation with flying wings the company developed the B-2 Spirit stealth bomber of the 1990s. In 1994, partly due to the loss of the Advanced Tactical Fighter contract to Lockheed Corporation and the removal of their proposal from consideration for the Joint Strike Fighter competition , the company bought Grumman to form Northrop Grumman . Bendix G-15 The Bendix G-15

960-569: The integrators were specified by writing an appropriate pattern of bits onto one of the tracks. In contrast to the prior ENIAC and UNIVAC I computers, which used electrical pulses to represent bits , the MADDIDA was the first computer to represent bits using voltage levels. It was also the first computer whose entire logic was specified in Boolean algebra . These features were an advancement from earlier digital computers that still had analog circuitry components. The original MADDIDA prototype

1000-486: The late 1950s and includes routines for minimum-access coding. Other programming aids include a supervisor program, a floating-point interpretive system named "Intercom", and ALGO , an algebraic language designed from the 1958 Preliminary Report of the ALGOL committee. 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 arithmetic

1040-459: The machine must wait for the complete recirculation of a delay line to obtain data from a given memory address. The problem is addressed in the G-15 by what the Bendix literature calls "minimum-access coding". Each instruction carries with it the address of the next instruction to be executed, allowing the programmer to arrange instructions such that when one instruction completes, the next instruction

1080-463: The program commented in jest "That the Caribbean was full of 'Snark infested waters'". After the MADDIDA design team left Northrop in 1950, another team, which included Max Palevsky , was hired to duplicate the machine for commercial distribution. By the end of 1952, six MADDIDAs had been delivered and installed, making it the bestselling commercial digital computer in the world at the time. One of

1120-439: The rate of the long lines, allowing fast access to frequently needed data. Even the machine's accumulators are implemented as drum lines: three double-word lines are used for intermediate storage and double-precision addition, multiplication, and division in addition to a one single-word accumulator. This use of the drum rather than flip-flops for the registers helped to reduce vacuum tube count. A consequence of this design

1160-598: The six was sold to the Navy Electronics Laboratory (see above photo). While developing the MADDIDA, the design team came to realize that a digital differential analyzer could be run on a general-purpose digital computer through the use of an appropriate problem-oriented language (POL) , such as Dynamo . A year after the first MADDIDA was demonstrated, Steele and the MADDIDA design team left Northrop, along with Irving S. Reed , in order to develop general-purpose computers. On July 16, 1950, they formed

1200-520: The successful T-38 Talon trainer) were developed and built. The F-5 was so successful that Northrop spent much of the 1970s and 1980s attempting to duplicate its success with similar lightweight designs. Their first attempt to improve the F-5 was the N-300 , which featured much more powerful engines and moved the wing to a higher position to allow for increased ordnance that the higher power allowed. The N-300

1240-531: The teaching assistants, a graduate student at UCLA, reported that one was used to check syntax of Fortran programs before they could be submitted to the 7094. The son of the engineer who arranged the use of the computer was a student in 1963. The program began as a six week residential science enrichment course for advanced rising high-school seniors, at the Thacher School in Ojai, CA, as a collaboration between

Magnetic Drum Digital Differential Analyzer - Misplaced Pages Continue

1280-563: 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 and unloading. Not unlike magnetic tape, the paper tape data are blocked into runs of 108 words or less since that

1320-700: The user never has to deal with this in normal programming. The user programs use the decimal numbers while the OS resides in the higher addresses. The G-15 is sometimes described as the first personal computer , because it has the Intercom interpretive system. The title is disputed by other machines, such as the LGP-30 (shipped in late 1956), and the DEC LINC (March 1962) and PDP-8 (March 1965), while some maintain that only microcomputers, such as those which appeared in

1360-456: The write head to the corresponding read head. Under normal operation, data are written back without change, but this data flow can be intercepted at any time, allowing the machine to update sections of a track as needed. This arrangement allows the designers to create "delay lines" of any desired length. In addition to the twenty "long lines" of 108 words each, there are four more short lines of four words each. These short lines recycle at 27 times

1400-456: Was Lord Kelvin 's tide-predicting machine , an analog computer completed in 1873. Steele hired Donald Eckdahl, Hrant (Harold) Sarkinssian, and Richard Sprague to work on the MADDIDA's germanium diode logic circuits and also to do magnetic recording. Together, this group developed the MADDIDA prototype between 1946 and 1949. The MADDIDA had 44 integrators implemented using a magnetic drum with six storage tracks. The interconnections of

1440-594: Was further developed into the P-530 with even larger engines, this time featuring a small amount of "bypass" ( turbofan ) to improve cooling and allow the engine bay to be lighter, as well as much more wing surface. The P-530 also included radar and other systems considered necessary on modern aircraft. When the Light Weight Fighter program was announced, the P-530 was stripped of much of its equipment to become

1480-523: Was hired as conceptual leader of the design group. Steele developed the concept for the DIDA, which would entail implementing an analog computer using only digital elements. When the decision was made to use magnetic drum memory (MAD) for the DIDA, the name was lengthened to MADDIDA (pronounced "Mad Ida"). In his design for MADDIDA, Steele was influenced by the analog computer invented in 1927 by Vannevar Bush , which had digital components. Another influence

1520-651: Was meant for scientific and industrial markets. The series was gradually discontinued when Control Data Corporation took over the Bendix computer division in 1963. 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. He made most of the design while working as a professor at Berkeley (where his graduate students included Niklaus Wirth ), and other universities. David C. Evans

1560-493: Was one of the Bendix engineers on the G-15 project. He would later become famous for his work in computer graphics and for starting up Evans & Sutherland with Ivan Sutherland . The G-15 was inspired by the Automatic Computing Engine (ACE). It is a serial-architecture machine , in which the main memory is a magnetic drum . It uses the drum as a recirculating delay-line memory , in contrast to

1600-459: Was that, unlike other computers with magnetic drums, the G-15 does not retain its memory when it is shut off. The only permanent tracks are two timing tracks recorded on the drum at the factory. The second track is a backup, as the tracks are liable to erasure if one of their amplifier tubes shorted out. The serial nature of the G-15's memory was carried over into the design of its arithmetic and control circuits. The adders work on one binary digit at

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