London, June 21 : The predecessor of the modern day computer, known as the Small Scale Experimental Machine, has reached its 60th anniversary.
According to a report in New Scientist, the Small Scale Experimental Machine, better known as "Baby", ran its first program at 11 am, 21 June 1948, at Manchester University in the UK.
Baby was the first "stored program computer", meaning it ran programs by loading them into a temporary memory store, or random-access memory (RAM), just as computers do today.
"That approach, and the fact the Baby was fully electronic, made it much easier to reprogram than previous computers," said Geoff Tootill, who helped design, build and test Baby.
"We didn't set out to change the future of computing, only to demonstrate that the new storage system worked. Building a small computer was the best way to do that," he added.
Baby's RAM was based on cathode ray tubes similar to those used in radar screens. A single tube could store 2048 bits of digital information, or 256 bytes. However, Baby only had a total of 1024 bits (128 bytes) of functional memory.
That new approach to computer memory was developed by Frederic Williams, who led Tootill and Tom Kilburn on the project.
"The only mathematical operation Baby could do was subtraction," said Tootill.
But, it was possible to carry out an addition using two subtractions and later on they later enabled Baby to perform multiplication.
The first program Baby ran successfully - after several failed attempts - could find the highest factor of any given number. Initially only tested on small numbers, the machine was soon tackling more difficult calculations.
Running the program on the number 218 took about 2.1 million steps and 52 minutes. Reading the results required the decoding of digital output shown on another CRT tube.