Erna Schneider Hoover(1926 — ?)
Erna Schneider Hoover
États-Unis
6 min read
Erna Schneider Hoover (1926-2025) was an American mathematician and computer scientist. In the 1960s she invented a computerized stored-program-controlled telephone switching system, revolutionizing the way calls were handled in telephone exchanges.
Frequently asked questions
Key Facts
- Born on June 19, 1926 in Irvington (New Jersey), died in 2025
- Earned a doctorate in philosophy and the foundations of mathematics from Yale University in 1951
- Joined Bell Labs in 1954
- Received one of the very first software patents in 1971 for her stored-program-controlled telephone switching system
- Her invention regulates the call load to prevent telephone exchanges from becoming overloaded
Works & Achievements
A principle that allows a computer to manage call routing in a telephone exchange. It replaced cumbersome electromechanical devices with programmed logic that was more flexible and more reliable.
An invention that continuously measures call traffic and regulates how calls are accepted to prevent exchanges from being overloaded. It is one of the first software patents in history.
Her work made possible the reliable operation of the first large electronic telephone exchanges deployed in the United States.
A work of logic and philosophy defended at Yale, which forged the rigorous reasoning underlying her future technical inventions.
Anecdotes
Erna Schneider Hoover sketched out the principles of her invention on a notepad while she was in the hospital, shortly after the birth of one of her daughters. While the doctors urged her to rest, she was thinking about how to keep telephone exchanges from collapsing during peak hours.
Her patent, filed in 1967 and granted in 1971, was one of the very first software patents ever issued anywhere in the world. At a time when people thought mainly in terms of machines and cables, she was protecting an idea: a clever way to make a program work.
Before becoming an engineer, Erna was a philosopher and logician: she had defended a doctoral dissertation at Yale on the foundations of mathematics. It was her mastery of logic, more than electronics, that allowed her to imagine a switching system controllable by computer.
When a telephone exchange received too many calls at the same time, it could freeze up completely. Erna's invention constantly measured the flow of calls and slowed down the acceptance of new requests to avoid overload — a “feedback” idea that modern networks still use today.
In 2008, Erna Schneider Hoover was inducted into the United States National Inventors Hall of Fame, alongside the greatest American inventors, in recognition of an invention that transformed telephony worldwide.
Primary Sources
A feedback control monitor designed to regulate the rate at which a stored-program data processing system accepts work requests, in order to prevent the telephone exchange from becoming overloaded.
The system periodically samples the rate of incoming calls and inhibits the acceptance of new requests when the exchange approaches saturation.
Erna Schneider Hoover is recognized for inventing a stored-program control principle that enabled computers to handle telephone switching reliably.
Key Places
Town in the suburbs of Newark where Erna Schneider was born in 1926 and where she grew up.
Women's college where Erna earned a degree in medieval history and philosophy in 1948.
Where she defended her doctorate on the philosophy and foundations of mathematics in 1951.
Major research center where Erna worked from 1954 until her retirement and designed her switching system.
Institution where she taught logic and mathematics before joining Bell Labs.
Suburban town near Murray Hill where Erna Schneider Hoover lived with her family during her career.