We start with the world's first general purpose electronic computer, the ENIAC, built in 1946 by a team of female mathematicians including Kathleen Kay McNulty. We speak to Gini Mauchly Calcerano, daughter of Kathleen Kay McNulty, who developed ENIAC.

Then we hear about the man who invented the original chatbot, called Eliza, but did not believe computers could achieve intelligence. We speak to Miriam Weizenbaum, daughter of Joseph Weizenbaum, who built Eliza chatbot.

Following that, Dr Hiromichi Fujisawa describes how his team at Waseda University in Japan developed the first humanoid robot in 1973, called WABOT-1.

Staying in Japan, the engineer Masahiro Hara explains how he was inspired to design the first QR code by his favourite board game.

Finally, Thérèse Izay Kirongozi recounts how the death of her brother drove her to build robots that manage traffic in the Democratic Republic of Congo.

Max Pearson presents a collection of the week's Witness History episodes. Our guest is Zoe Kleinman, the BBC's technology editor.

(Photo: Robots manage traffic in Kinshasa, Democratic Republic of Congo. Credit: Federico Scoppa/AFP)