Marchant Calculator
Encyclopedia
The Marchant Calculating Machine Co. was founded in 1911 by Rodney and Alfred Marchant in Oakland, California
.
The company built mechanical, and then electromechanical calculator
s which had a reputation for reliability. First models were similar to the Odhner arithmometer
. In 1918, employee Carl Friden
designed a new model in response to patent challenges. It was a great success, and Friden became the chief designer until he left in 1934 to found his own company. In 1958 the company was acquired by the Smith Corona
typewriter
company in a diversification move that proved unsound; the company, which was now known as SCM, tried to stay competitive by introducing the SCM Cogito 240SR electronic calculator (designed by Manhattan Project
veteran Stan Frankel
) in 1965. Within a few years a tidal wave of cheaper electronic calculators had devastated their business, and by the mid 1980s, SCM's typewriter business, too, had been ruined by the advent of inexpensive personal computer
s used as word processor
s.
in the corresponding column of the keyboard. A '1' in the keyboard caused its dial to move the slowest, while a '9', the fastest. Probably the only other such machine was the European Mercedes Euklid, which had a very different (and apparently much simpler) design.
Carrying to the next higher order was done (effectively) by a 10:1 gear ratio
, rather like traditional watthour-meter
dials. This was probably unique in a calculator.
While running consecutive 'add' cycles to develop a product in multiplication
, much of the mechanism was running at constant speeds. All other mechanical calculators had result dials that moved only at one speed, but for different amounts of time, naturally for longer times when larger digits were to be entered. They started quickly, ran at one speed, and stopped quickly. (They also had mechanisms to prevent overshoot (known as coasting) when they stopped.)
In the Marchant, each column had its own mechanism that might be described as a nine-speed pre-selector transmission. Once engaged, that was what made the dials move at speeds proportional to the digit in that column. This meant that the machine contained, in all, several hundred individual gears.
Carries from lower-order digits came in via one planetary differential per dial. If one held down the + bar, in neighboring columns to the left (with zeros for them in the keyboard), one could see two or maybe three higher-order dials moving at the speeds one would expect.
Watthour meter dials, like the hour hand of a clock, make no attempt to point to the correct digit, if the dial to the right is between, for example, 3 and 7, or so. Such misalignment would be intolerable in a calculator's dials, so each of the Marchant's dials had a constant-lead ("snail") cam
attached. Omitting important details, this cam determined the amount of movement needed to realign the result dials. That correction was applied by a second spur-gear differential, again, one per dial.
Some calculators that had been serviced had dials that were mispositioned by (probably) 3.6 degrees; the gears weren't quite meshed correctly when reassembled.
The calculator was very complicated compared to, for example the Friden STW, a machine notable for its relative internal simplicity. Much of the Marchant's control mechanism was beneath the keys, and had about 25 "layers" of levers, linkages, latches, and such. It had three driveshaft
s, extending across the mechanism. Most other calculators had only one.
Any other mechanical calculator capable of fully automatic division
(and there were many), subtracted
until the accumulator went into overdraft ("subtracted one time too many"), then added once to restore the value in the accumulator. The Marchant, however, contained a chain of analog comparators
to anticipate the overdraft, and prepare for the next quotient digit.
The Marchant mechanism, internally, differed profoundly in many respects from other makes of calculators of the same general variety. By virtue of sophistication (and complexity), it gained a considerable speed advantage, compared to other designs.
Oakland, California
Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...
.
The company built mechanical, and then electromechanical calculator
Calculator
An electronic calculator is a small, portable, usually inexpensive electronic device used to perform the basic operations of arithmetic. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators.The first solid-state electronic...
s which had a reputation for reliability. First models were similar to the Odhner arithmometer
Odhner Arithmometer
The Odhner Arithmometer was a very successful pinwheel calculator invented in Russia in 1873 by W. T. Odhner, a Swedish immigrant. Its industrial production officially started in 1890 in Odhner's Saint Petersburg workshop...
. In 1918, employee Carl Friden
Carl Friden
Carl Friden was the Swedish born American mechanical engineer and businessman who founded the Friden Calculating Machine Company .-Background:...
designed a new model in response to patent challenges. It was a great success, and Friden became the chief designer until he left in 1934 to found his own company. In 1958 the company was acquired by the Smith Corona
Smith Corona
Smith Corona or the SCM Corporation is a US typewriter and calculator company. Once a large U.S. manufacturer, the company experienced sales declines in typewriters in the mid-1980s due to the introduction of PC-based word processing...
typewriter
Typewriter
A typewriter is a mechanical or electromechanical device with keys that, when pressed, cause characters to be printed on a medium, usually paper. Typically one character is printed per keypress, and the machine prints the characters by making ink impressions of type elements similar to the pieces...
company in a diversification move that proved unsound; the company, which was now known as SCM, tried to stay competitive by introducing the SCM Cogito 240SR electronic calculator (designed by Manhattan Project
Manhattan Project
The Manhattan Project was a research and development program, led by the United States with participation from the United Kingdom and Canada, that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army...
veteran Stan Frankel
Stan Frankel
Stanley Phillips "Stan" Frankel was an American computer scientist. He was born in Los Angeles, attended graduate school at the University of Rochester, received his PhD in physics from the University of California, Berkeley, and began his career as a post-doc student under J. Robert Oppenheimer...
) in 1965. Within a few years a tidal wave of cheaper electronic calculators had devastated their business, and by the mid 1980s, SCM's typewriter business, too, had been ruined by the advent of inexpensive personal computer
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
s used as word processor
Word processor
A word processor is a computer application used for the production of any sort of printable material....
s.
Calculator design
The first Marchant calculators differed greatly from their later Silent Speed Proportional Gears machines, which were by far the fastest of their type, running at 1,300 cycles per minute. These machines are of considerable technical interest, and are far better known than the earliest ones. Their mechanical design was very unusual in that their result dials (sums, differences, and products) moved at speeds proportional to the digitNumerical digit
A digit is a symbol used in combinations to represent numbers in positional numeral systems. The name "digit" comes from the fact that the 10 digits of the hands correspond to the 10 symbols of the common base 10 number system, i.e...
in the corresponding column of the keyboard. A '1' in the keyboard caused its dial to move the slowest, while a '9', the fastest. Probably the only other such machine was the European Mercedes Euklid, which had a very different (and apparently much simpler) design.
Carrying to the next higher order was done (effectively) by a 10:1 gear ratio
Gear ratio
The gear ratio of a gear train is the ratio of the angular velocity of the input gear to the angular velocity of the output gear, also known as the speed ratio of the gear train. The gear ratio can be computed directly from the numbers of teeth of the various gears that engage to form the gear...
, rather like traditional watthour-meter
Electricity meter
An electricity meter or energy meter is a device that measures the amount of electric energy consumed by a residence, business, or an electrically powered device....
dials. This was probably unique in a calculator.
While running consecutive 'add' cycles to develop a product in multiplication
Multiplication
Multiplication is the mathematical operation of scaling one number by another. It is one of the four basic operations in elementary arithmetic ....
, much of the mechanism was running at constant speeds. All other mechanical calculators had result dials that moved only at one speed, but for different amounts of time, naturally for longer times when larger digits were to be entered. They started quickly, ran at one speed, and stopped quickly. (They also had mechanisms to prevent overshoot (known as coasting) when they stopped.)
In the Marchant, each column had its own mechanism that might be described as a nine-speed pre-selector transmission. Once engaged, that was what made the dials move at speeds proportional to the digit in that column. This meant that the machine contained, in all, several hundred individual gears.
Carries from lower-order digits came in via one planetary differential per dial. If one held down the + bar, in neighboring columns to the left (with zeros for them in the keyboard), one could see two or maybe three higher-order dials moving at the speeds one would expect.
Watthour meter dials, like the hour hand of a clock, make no attempt to point to the correct digit, if the dial to the right is between, for example, 3 and 7, or so. Such misalignment would be intolerable in a calculator's dials, so each of the Marchant's dials had a constant-lead ("snail") cam
Cam
A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice-versa. It is often a part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path...
attached. Omitting important details, this cam determined the amount of movement needed to realign the result dials. That correction was applied by a second spur-gear differential, again, one per dial.
Some calculators that had been serviced had dials that were mispositioned by (probably) 3.6 degrees; the gears weren't quite meshed correctly when reassembled.
The calculator was very complicated compared to, for example the Friden STW, a machine notable for its relative internal simplicity. Much of the Marchant's control mechanism was beneath the keys, and had about 25 "layers" of levers, linkages, latches, and such. It had three driveshaft
Driveshaft
A drive shaft, driveshaft, driving shaft, propeller shaft, or Cardan shaft is a mechanical component for transmitting torque and rotation, usually used to connect other components of a drive train that cannot be connected directly because of distance or the need to allow for relative movement...
s, extending across the mechanism. Most other calculators had only one.
Any other mechanical calculator capable of fully automatic division
Division (mathematics)
right|thumb|200px|20 \div 4=5In mathematics, especially in elementary arithmetic, division is an arithmetic operation.Specifically, if c times b equals a, written:c \times b = a\,...
(and there were many), subtracted
Subtraction
In arithmetic, subtraction is one of the four basic binary operations; it is the inverse of addition, meaning that if we start with any number and add any number and then subtract the same number we added, we return to the number we started with...
until the accumulator went into overdraft ("subtracted one time too many"), then added once to restore the value in the accumulator. The Marchant, however, contained a chain of analog comparators
Comparator
In electronics, a comparator is a device that compares two voltages or currents and switches its output to indicate which is larger. They are commonly used in devices such as Analog-to-digital converters .- Input voltage range :...
to anticipate the overdraft, and prepare for the next quotient digit.
The Marchant mechanism, internally, differed profoundly in many respects from other makes of calculators of the same general variety. By virtue of sophistication (and complexity), it gained a considerable speed advantage, compared to other designs.
External links
- SCM Marchant Cogito 240SR calculator
- Stanley Frankel, Recirculating Memory Timing, filed February, 1964, issued June, 1970
- Marchant Figurematic calculator Detailed technical description, with numerous photographs, by an engineer
- History of Marchant at the History Museum at St.Gertrude in Cottonwood, IdahoCottonwood, IdahoCottonwood is a city in Idaho County, Idaho, United States. The population was 900 at the 2010 census. Cottonwood is just west of U.S. Route 95, between Grangeville and Lewiston.-Cottonwood Butte:...