Erna Schneider Hoover

Dr. Erna Schneider Hoover (born June 19, 1926) is an American mathematician notable for inventing a computerized telephone switching method which "revolutionized modern communication" according to several reports.[1][4] It prevented system overloads by monitoring call center traffic and prioritizing tasks[4] on phone switching systems to enable more robust service during peak calling times.[1] At Bell Laboratories where she worked for over 32 years,[5] Hoover was described as an important pioneer for women in the field of computer technology.[2]

Erna Schneider Hoover
Erna Schneider

June 19, 1926 (age 92)
CitizenshipUnited States
Alma materWellesley B.A.,
Yale Ph.D.
Known forComputerized system
for phone traffic[2]
Spouse(s)Charles Wilson Hoover, Jr.
AwardsNational Inventors Hall of Fame, 2008[3]
Wellesley alumni
achievement award[2]
Scientific career
InstitutionsBell Labs
ThesisAn Analysis of
Conditional Sentences[2]

Early life

Erna Schneider was born on June 19, 1926[6] in Irvington, New Jersey.[2] Her family lived in South Orange, New Jersey and her father was a dentist and her mother was a teacher.[2] She had a younger brother who died from polio at the age of five.[2] She loved swimming, sailing, canoeing, and was interested in science at an early age. According to one source, she read the biography of Marie Curie which suggested to her that she could succeed in a scientific field despite the prevailing ideas about gender roles at the time.[2] She graduated from Columbia High School in nearby Maplewood in 1944, which would later induct her into its hall of fame in 2007.[7]

Hoover attended Wellesley College where she studied classical and medieval philosophy and history.[1][6][8][9] She graduated from Wellesley in 1948 with honors, earning a bachelor's degree, and she was inducted into Phi Beta Kappa and was honored as a Durant Scholar.[2] She earned her Ph.D from Yale University in philosophy and foundations of mathematics in 1951.[1][6]


Hoover was a professor at Swarthmore College from 1951-54[1] where she taught philosophy and logic.[2] However, she had been unable to win a tenure-track position, possibly because of her gender and marital status, according to one view. In 1953, she married Charles Wilson Hoover, Jr., and he was very supportive of his wife's career pursuits.[2] In 1954, she joined Bell Labs as a senior technical associate, and was promoted in 1956. According to one source, the internal training program was the "equivalent of a master's degree in computer science."[2] Switching systems were moving from electronic to computer-based technologies. Problems happened when a call center would be inundated with thousands of calls in a short amount of time, overwhelming the unreliable electronic relays, and causing the entire system to "freeze up."[2]

Hoover used her knowledge of symbolic logic and feedback theory to program the control mechanisms of a call center to use data about incoming calls to impose order on the whole system.[2] It used computer electronic methods to monitor the frequency of incoming calls[10] at different times.[11] Her method gave priority to processes that were concerned with the input and output of the switch over processes that were less important such as record keeping and billing.[2][6] The computer, as a result, would adjust the call center's acceptance rate automatically, greatly reducing the overloading problem.[9] The system became known as stored program control.[11]

Hoover's thinking about the invention happened while she was in a hospital recuperating after having given birth to her second daughter, according to several sources.[11][6][12] Lawyers for Bell Labs handling the patent had to go to her house to visit her while she was on maternity leave so that she could sign the papers.[1] The result of the invention was much more robust service to callers during peak load times:

To my mind it was kind of common sense ... I designed the executive program for handling situations when there are too many calls, to keep it operating efficiently without hanging up on itself. Basically it was designed to keep the machine from throwing up its hands and going berserk.

— Erna Schneider Hoover, 2008[4]
The College of New Jersey (TCNJ) 27
Hoover is a lifelong advocate for higher education. As board member of The College of New Jersey, she was instrumental in its efforts to attract the state's best students, hire women faculty, and win more state aid.

For her invention, termed Feedback Control Monitor for Stored Program Data Processing System, Hoover was awarded patent #3,623,007 in November 1971, one of the first software patents ever issued.[10] The patent was applied for in 1967 and issued in 1971.[2][13] As a result of her invention, she became the first woman supervisor of a technical department at Bell Labs.[4][6] She headed the operations support department in 1987.[5] The principles of her invention are still being used in telecommunications equipment in the 21st-century.

Hoover worked on various high-level applications such as research radar control programs of the Safeguard Anti-Ballistic Missile System, which were systems to intercept incoming intercontinental ballistic missile warheads.[2] Her department worked on artificial intelligence methods, large databases, and transactional software to support large telephone networks.[2] She worked at Bell Labs for 32 years until retiring in 1987.[5] In addition, she served on the boards of higher education organizations in New Jersey.[2] As a member of the board of Trustees of The College of New Jersey, she was described as a visionary who was instrumental in increasing women faculty as well as enrolling the "best prepared high school graduates" in the state, and she helped build the college into a respected institution of higher education by lobbying extensively for state funding.[14]


She was awarded one of the first patents for computer software.[2] She was elected as a member of the National Inventors Hall of Fame in 2008.[11] She received the Wellesley College alumni achievement award.[2]


  1. ^ a b c d e f g "Hall of Fame -- induction info". National Inventors Hall of Fame. 2008. Archived from the original on 2012-04-28. Retrieved 2012-06-05.
  2. ^ a b c d e f g h i j k l m n o p q r s t u "Erna Hoover -- Biography". World of Computer Science. 2012. Retrieved 2012-06-17.
  3. ^ National Inventors Hall of Fame Archived 2010-07-09 at the Wayback Machine website. Accessed March 18, 2010.
  4. ^ a b c d Amy Ellis Nutt (June 18, 2008). "Fame calls on 2 titans of telephony in NJ". The Star-Ledger. Retrieved 2012-06-05.
  5. ^ a b c Calvin Sims (March 9, 1987). "BELL LABS: ADAPTING TO MONOPOLY'S END". The New York Times. Retrieved 2012-06-05.
  6. ^ a b c d e f "Erna Schneider Hoover profile". Global History Network of IEEE. 2012. Retrieved 2012-06-17.
  7. ^ Hall of Fame, Columbia High School. Accessed November 12, 2018.
  8. ^ "Biography". Fact Monster. 2012-06-17. Retrieved 2012-06-17.
  9. ^ a b "Erna Schneider Hoover profile". 2012-06-17. Retrieved 2012-06-17.
  10. ^ a b Alpha Doggs (February 15, 2008). "Phone switching pioneers to be inducted in National Inventors Hall of Fame". Network World. Retrieved 2012-06-17.
  11. ^ a b c d "Hoover, Erna (Schneider)". Smart Computing. 2012. Retrieved 2012-06-17.
  12. ^ "Inventor of the Week". Massachusetts Institute of Technology. 2012. Retrieved 2012-06-17.
  13. ^ See Patent #3623007 November 23, 1971
  14. ^ "Former TCNJ Board member elected to National Inventors Hall of Fame". The College of New Jersey. February 18, 2008. Retrieved 2012-06-17.

External links

Bell Labs

Nokia Bell Labs (formerly named AT&T Bell Laboratories and Bell Telephone Laboratories) is an industrial research and scientific development company owned by Finnish company Nokia. Its headquarters are located in Murray Hill, New Jersey. Other laboratories are located around the world (with some in the United States). Bell Labs has its origins in the complex past of the Bell System.

In the late 19th century, the laboratory began as the Western Electric Engineering Department and was located at 463 West Street in New York City. In 1925, after years of conducting research and development under Western Electric, the Engineering Department was reformed into Bell Telephone Laboratories and under the shared ownership of American Telephone & Telegraph Company and Western Electric.

Researchers working at Bell Labs are credited with the development of radio astronomy, the transistor, the laser, the photovoltaic cell, the charge-coupled device (CCD), information theory, the Unix operating system, and the programming languages C, C++, and S. Nine Nobel Prizes have been awarded for work completed at Bell Laboratories.

Communications receiver

A communications receiver is a type of radio receiver used as a component of a radio communication link. This is in contrast to a broadcast receiver which is used to receive radio broadcasts. A communication receiver receives parts of the radio spectrum not used for broadcasting, that includes amateur, military, aircraft, marine, and other bands. They are often used with a radio transmitter as part of a two way radio link for shortwave radio or amateur radio communication, although they are also used for shortwave listening.

Evelyn Boyd Granville

Evelyn Boyd Granville (born May 1, 1924) was the second African-American woman to receive a Ph.D. in mathematics from an American University; she earned it in 1949 from Yale University (she attended Smith College before Yale). She performed pioneering work in the field of computing.

Henry Sutton (inventor)

Henry Sutton (4 September 1855, Ballarat, Victoria – 28 July 1912) was an Australian designer, engineer, and inventor credited with contributions to early developments in electricity, aviation, wireless communication, photography and telephony.

June 19

June 19 is the 170th day of the year (171st in leap years) in the Gregorian calendar. There are 195 days remaining until the end of the year.

List of American scientists

This is a list of American scientists.

List of Wellesley College people

The following is a list of individuals associated with Wellesley College through attending as a student, or serving as a member of the faculty or staff. Dates indicate the year of graduation.

MCI Communications

MCI Communications Corp. was an American telecommunications company that was instrumental in legal and regulatory changes that led to the breakup of the AT&T monopoly of American telephony and ushered in the competitive long-distance telephone industry. It was headquartered in Washington, D.C.Founded in 1963, it grew to be the second-largest long-distance provider in the U.S. It was purchased by WorldCom in 1998 and became MCI WorldCom, with the name afterwards being shortened to WorldCom in 2000. WorldCom's financial scandals and bankruptcy led that company to change its name in 2003 to MCI Inc.


In telecommunications and computer networks, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource. For example, in telecommunications, several telephone calls may be carried using one wire. Multiplexing originated in telegraphy in the 1870s, and is now widely applied in communications. In telephony, George Owen Squier is credited with the development of telephone carrier multiplexing in 1910.

The multiplexed signal is transmitted over a communication channel such as a cable. The multiplexing divides the capacity of the communication channel into several logical channels, one for each message signal or data stream to be transferred. A reverse process, known as demultiplexing, extracts the original channels on the receiver end.

A device that performs the multiplexing is called a multiplexer (MUX), and a device that performs the reverse process is called a demultiplexer (DEMUX or DMX).

Inverse multiplexing (IMUX) has the opposite aim as multiplexing, namely to break one data stream into several streams, transfer them simultaneously over several communication channels, and recreate the original data stream.

NPL network

The NPL Network or NPL Data Communications Network was a local area computer network operated by a team from the National Physical Laboratory in England that pioneered the concept of packet switching. Following a pilot experiment during 1967, elements of the first version of the network, Mark I, became operational during 1969 then fully operational in 1970, and the Mark II version operated from 1973 until 1986. The NPL network, followed by the wide area ARPANET in the United States, were the first two computer networks that implemented packet switching, and were interconnected in the early 1970s. The NPL network was designed and directed by Donald Davies.

Rotary dial

A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing. It is used when initiating a telephone call to transmit the destination telephone number to a telephone exchange.

On the rotary phone dial, the digits are arranged in a circular layout so that a finger wheel may be rotated with one finger from the position of each digit to a fixed stop position, implemented by the finger stop, which is a mechanical barrier to prevent further rotation.

When released at the finger stop, the wheel returns to its home position by spring action at a speed regulated by a governor device. During this return rotation, the dial interrupts the direct electrical current of the telephone line (local loop) a specific number of times for each digit and thereby generates electrical pulses which the telephone exchange decodes into each dialed digit. Each of the ten digits is encoded in sequences of up to ten pulses so the method is sometimes called decadic dialling.

The first patent for a rotary dial was granted to Almon Brown Strowger (November 29, 1892) as U.S. Patent 486,909, but the commonly known form with holes in the finger wheel was not introduced until ca. 1904. While used in telephone systems of the independent telephone companies, rotary dial service in the Bell System in the United States was not common until the introduction of the Western Electric model 50AL in 1919.From the 1980s onward, the rotary dial was gradually supplanted by dual-tone multi-frequency push-button dialing, first introduced to the public at the 1962 World's Fair under the trade name "Touch-Tone". Touch-tone technology primarily used a keypad in form of a rectangular array of push-buttons for dialing.

Stored program control

Stored program control (SPC) was a telecommunications technology used for telephone exchanges controlled by a computer program stored in the memory of the switching system. SPC was the enabling technology of electronic switching systems (ESS) developed in the Bell System in the 1950s, and may be considered the third generation of switching technology. Stored program control was invented by Bell Labs scientist Erna Schneider Hoover in 1954 who reasoned that computer software could control the connection of telephone calls.


The telex network was a public switched network of teleprinters similar to a telephone network, for the purposes of sending text-based messages. Telex was a major method of sending written messages electronically between businesses in the post-World War II period. Its usage went into decline as the fax machine grew in popularity in the 1980s.

The "telex" term refers to the network, not the teleprinters; point-to-point teleprinter systems had been in use long before telex exchanges were built in the 1930s. Teleprinters evolved from telegraph systems, and, like the telegraph, they used binary signals, which means that symbols were represented by the presence or absence of a pre-defined level of electric current. This is significantly different from the analog telephone system, which used varying voltages to represent sound. For this reason, telex exchanges were entirely separate from the telephone system, with their own signalling standards, exchanges and system of "telex numbers" (the counterpart of telephone numbers).

Telex provided the first common medium for international record communications using standard signalling techniques and operating criteria as specified by the International Telecommunication Union. Customers on any telex exchange could deliver messages to any other, around the world. To lower line usage, telex messages were normally first encoded onto paper tape and then read into the line as quickly as possible. The system normally delivered information at 50 baud or approximately 66 words per minute, encoded using the International Telegraph Alphabet No. 2. In the last days of the telex networks, end-user equipment was often replaced by modems and phone lines, reducing the telex network to what was effectively a directory service running on the phone network.

Voice of Russia

The Voice of Russia (Russian: Голос России, tr. Golos Rossii), commonly abbreviated VOR, was the Russian government's international radio broadcasting service from 1993 until 2014, when it was reorganised as Radio Sputnik. Its interval signal was a chime version of 'Majestic' chorus from the Great Gate of Kiev portion of Pictures at an Exhibition by Mussorgsky.

Network topology
and switching

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