page_title: Premium Bond
section_title: ERNIE
hierarchical_section_title: Premium Bond / ERNIE
caption_attribution_description: Photo of ERNIE 1 the first premium bond number producing machine in the science museum
context_page_description: A Premium Bond is a lottery bond issued by the United Kingdom government since 1956. At present it is issued by the government's National Savings and Investments agency.
  The principle behind Premium Bonds is that rather than the stake being gambled, as in a usual lottery, it is the interest on the bonds that is distributed by a lottery. The bonds are entered in a monthly prize draw and the government promises to buy them back, on request, for their original price.
  The government pays interest into the bond fund from which a monthly lottery distributes tax-free prizes to bondholders whose numbers are selected randomly. The machine that generates the numbers is called ERNIE, for Electronic Random Number Indicator Equipment. Prizes range from £25 to £1,000,000 and the odds of a £1 bond winning a prize in a given month are 24,500 to 1.
  Investors can buy bonds at any time and they must be held for a calendar month before they qualify for a prize. Numbers are entered in the draw each month, with an equal chance of winning, until the bond is cashed. As of 2019, each person may own bonds up to £50,000. Since 1 February 2019, the minimum purchase amount for Premium Bonds has been £25.
context_section_description: ERNIE is a hardware random number generator. The first ERNIE was built at the Post Office Research Station by a team led by Sidney Broadhurst. The designers were Tommy Flowers and Harry Fensom and it derives from Colossus, one of the world's first digital computers. It was introduced in 1957, with the first draw on 1 June, and generated bond numbers from the signal noise created by neon tubes.  The name is an acronym for Electronic Random Number Indicator Equipment. ERNIE 1 is in the collections of the Science Museum in London and was on display between 2008 and 2015.  
  ERNIE 2 replaced the first ERNIE in 1972.
  ERNIE 3 in 1988 was the size of a personal computer; at the end of its life it took five and a half hours to complete its monthly draw.
  In August 2004, ERNIE 4 was brought into service in anticipation of an increase in prizes each month from September 2004. Developed by LogicaCMG, it is 500 times faster than the original and generates a million numbers an hour; these are checked against a list of valid bonds. By comparison, the original ERNIE generated 2,000 numbers an hour and was the size of a van.
  ERNIE 4 used thermal noise in transistors as its source of randomness to generate true random numbers; the original ERNIE used a gas neon diode. In contrast, pseudorandom numbers, although sometimes simply referred to as random, are produced deterministically by the algorithm used to generate them. The randomness of ERNIE's numbers derived from random statistical fluctuations in the physical processes involved. ERNIE's output was independently tested each month by the Government Actuary's Department, the draw being valid only if it was certified to be statistically consistent with randomness. At the end of its life it was moved to Bletchley Park's National Museum of Computing. 
  ERNIE 5, the latest model, was brought into service in March 2019, and is a quantum random number generator built by ID Quantique. It uses quantum technology to produce random numbers through light, replacing the former 'thermal noise' method. Running at speeds 21,000 times faster than the first ERNIE, it can produce 3 million winners in just 12 minutes each month.
caption: ERNIE 1
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