Photos: The tech that holds up the net

Packet switching turns 40...

Packet switching is one of the crucial technologies that made the internet possible.

It's 40 years since the technique was invented by a team at the National Physical Laboratory (NPL) in Bushy Park, Middlesex, led by professor Donald Davies (pictured in 1974).

Speaking to silicon.com, NPL chief scientist, professor John Pethica explained: "The whole idea of packet switching is what underlies the idea of a set of distributed nodes, which is now the internet. It's the hardware side of the internet."

Photo credit: NPL

Packet switching is essentially the routing of parcels of data between nodes using data links shared with other data.

The technique was adopted by scientists at US Department of Defence developing the Arpanet (Advanced Research Projects Agency Network), widely seen as the predecessor of the internet.

Pethica said: "Two things happened. One is it influenced the people generating the Arpanet around that time - they effectively took on the key structures [Davies] proposed and fed them into the Arpanet."

This is the Pilot Ace computer at NPL in 1950. This was one of the first modern computers in the world and the first in London. Donald Davies was one of the main contributors to the design of the machine and its programs.

Photo credit: NPL

The invention of packet switching also meant NPL was home to another first.

Pethica said: "It meant also the first LAN in the world was actually built at NPL, not in the US. So it wasn't just a concept, it was actually built and made."

This is NPL's first attempt at a full-scale Ace computer, which was completed in 1957.

Photo credit: NPL

Prince Philip (left) visited the NPL in 1952 to take a look at the technology being developed, including the differential analyser he's looking at in this picture.

Photo credit: NPL

Here's someone working on NPL's Deuce computer in 1956.

Alan Turing - widely seen as the father of modern computer science - worked at the NPL in the 1940s after his time at Bletchley Park where he was involved in cracking German code during World War II.

Photo credit: NPL

The KDF 9 computer was another one of the systems built by scientists at NPL, seen here in 1964.

Following his pioneering work on packet switching, Donald Davies worked on network security during the 1980s.

Photo credit: NPL