Virtual ERNIE

A virtual simulation of E.R.N.I.E - Electronic Random Number Indicator Equipment

Find Out More Run Virtual ERNIE

Who is ERNIE?

E.R.N.I.E stood for the Electronic Random Number Indicator Equipment and is a hardware random number generator built in 1956 to find winners each month for the Post Office Savings Bank and National Savings (now National Savings and Investments, NS&I) Premium Bond prize draw.

Designed by Harry Fensom together with Tommy Flowers, the inventor of Colossus, the first digital electronic programmable computer who both worked at the GPO Research Station at Dollis Hill.

What do I need to know to run it!
Instructions for use

Moving and Zooming

To move around, click and drag on a blank area of screen or use the scroll bars.

If you want a closer look at ERNIE, use your mouse wheel while on the page or alternatively, use the Zoom Level buttons on the control at the top left of the screen. On a tablet or phone: Just pinch zoom as normal

Click or swipe switches

Try clicking the switches or keys - basically anywhere you see the hand icon.

For switches, click or press at the top of the switch to move it upwards and at the bottom of the switch to move it downwards.

Look for Info Boxes

Look for the helpful blue info boxes. These give extra information about panels you can interact with and some options and selections.


Try opening the drawers on the desk for manuals and a video, these will give you more information on how ERNIE was used.

To begin, why not download this PDF guide

Getting Started

What does it do?

Credits and links

A number of people I need to say thanks and tip my hat to... .. The National Museum of Computing where my obsession was sparked! .. The home of E.R.N.I.E .. The Science Museum Group Collection for their high resolution images of ERNIE

FuseMetrix Group .. My employers who put up with me nattering about Colossus and allow me space on their servers to run this website!

Also thanks to Rod Willerton for uploading a digital version of the original GPO 16mm film, made in 1964, "The Importance of Being E.R.N.I.E" which was invaluable in learning more of exactly how ERNIE worked and was used.

Let me know what you think!

Have I got something wrong, it doesn't work quite correctly on your computer or maybe you just want to say hi - follow @VirtualColossus on Twitter or Facebook or send me a message.

Martin Gillow

I won't share your email with anyone else.