Babbage’s Difference Engine and other historic computers
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Babbage Difference Engine No. 2
Babbage Difference Engine No. 2
Charles Babbage designed the first automatic computing engines, but none of his creations was ever fully built.
In 2002, London’s Science Museum completed the first fully-functional Difference Engine. A duplicate machine was constructed for Nathan Myhrvold, tech millionaire and former chief technology officer at Microsoft. That second machine is on display at the Computer History Museum in Mountain View, CA.
The photos in this gallery were taken by Jitze Couperus in January, 2010 during a visit to the museum. Mr. Couperus has graciously allowed us to republish his photos of Babbage’s Difference Engine and Royal McBee LGP-30 and Control Data Corporation (CDC) 6600.
Photo credit: Jitze Couperus
Polynomial calculations
Polynomial calculations
Babbage designed his difference engine to calculate and tabulate the value of seventh order polynomials to 31 decimal places. His intent was to eliminate the possibility of human error when calculating printed mathematical tables.
Photo credit: Jitze Couperus
Difference Engine No. 2 specifications
Difference Engine No. 2 specifications
According to the Computer History Museum, Difference Engine No. 2 has 8,000 parts, weighs five tons, and measures 11 feet long.
Photo credit: Jitze Couperus
Difference Engine power source
Difference Engine power source
Difference Engine No. 2 is operated by cranking a handle.
Photo credit: Jitze Couperus
Gears and cams
Gears and cams
Each engine cycle (four cracks of the handle) produces one result.
Photo credit: Jitze Couperus
Seven vertical counting mechanisms
Seven vertical counting mechanisms
Difference Engine No. 2 had seven vertical counting mechanisms. Each with a column of 31 numbered gears.
Photo credit: Jitze Couperus
Adding across columns
Adding across columns
These small brass arms allow the machine to carry the calculation across the seven columns.
Photo credit: Jitze Couperus
Gears, wheels, and counterweights
Gears, wheels, and counterweights
Photo credit: Jitze Couperus
Another crank handle
Another crank handle
Photo credit: Jitze Couperus
Crank handle second view
Crank handle second view
Photo credit: Jitze Couperus
Output printer
Output printer
Babbage designed the machine to produce printed mathematical tables. Difference Engine No. 2 has an output printer that prints each 31 digit results in ink. The machines also imprints the results in a soft material (such as plaster). The plaster cast would then be used to make a printing plate.
Photo credit: Jitze Couperus
Setting the machine's input parameters
Setting the machine's input parameters
Photo credit: Jitze Couperus
Double checking the settings
Double checking the settings
Photo credit: Jitze Couperus
Turning the crank
Turning the crank
As the crank is turned, the machine being calculating the results.
Photo credit: Jitze Couperus
Electrodata E-205 (1954)
Electrodata E-205 (1954)
From the Computer History Museum’s description:
“The vacuum-tube based E-205 used a rotating magnetic drum for main memory.”
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
Royal McBee LGP-30 (1956)
Royal McBee LGP-30 (1956)
The LGP-30 was originally manufactured by Royal McBee, a typewriter company. Royal McBee eventually sold their computer division to Control Data Corporation (CDC).
Featured in Ed Nather’s “The Story of Mel”, the LGP-30 has secured a place in hacker lore.
From the Computer History Museum’s description:
“The LGP-30 was a small drum-based computer marketed to engineering, scientific and educational users.”
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
Little Character (1958)
Little Character (1958)
Built for the Control Data Corporation (CDC) in 1958, Seymour Cray’s Little Character was designed to show that a computer could be built from modular circuit boards. It was used as a prototype for the CDC 160 and CDC 1604 computers.
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
Zuse Z23 (1961)
Zuse Z23 (1961)
From the Computer History Museum’s description:
“The Z23 contained both a magnetic drum and a small magnetic core memory. Inventor Konrad Zuse began development of the Z23 in 1958 and the first machine was delivered three years later.”
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
CDC 160A (1962)
CDC 160A (1962)
According to the Computer History Museum, the CDC 160A, had 32K memory, ran at a speed of 78,125 Add/s, and cost $110,000.
“It came with a high-speed paper-tape reader, paper tape punch, and a typewriter. A FORTRAN compiler was also available for those who wanted to write their own programs.”
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
CDC 6600 (1964)
CDC 6600 (1964)
From the Computer History Museum’s description:
“Designed by Seymour Cray, [the CDC 6600] executed about three million instructions per second and remained the fastest machine for five years, until Cray produced his next supercomputer, the 7600.”
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
CDC 6600 wiring (1964)
CDC 6600 wiring (1964)
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
CDC 7600 (1971)
CDC 7600 (1971)
From the Computer History Museum’s description:
“About five times faster than the CDC 6600, scientific and government institutions primarily used both machines to execute large mathematical programs written in FORTRAN.”
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
ETA-10 (1986)
ETA-10 (1986)
From the Computer History Museum’s description:
“The ETA-10 incorporated 44-layer CMOS boards that were cooled by liquid nitrogen.”
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
Cray Y-MP (1988)
Cray Y-MP (1988)
From the Computer History Museum’s description:
“The Cray Y-MP was the first supercomputer to successfully reach the one gigaflop (one billion floating point operations per second) operational milestone.”
For more information, check out the Computer History Museum’s description of this machine.
Photo credit: Jitze Couperus
