Hello and welcome to the History Hour podcast from the BBC World Service with me Max Pearson,

the past brought to life by those who were there.

This week, the world's first office computer.

It took the idea of an ordinary mechanical calculating machine and decided

to turn it into electronics.

Also, we relived the moment in 1985 when the sacred red rock at Uluru was handed back to Australia's

indigenous people. How India struggled to cope with economic liberalisation in the 1990s.

And through the death of a boy in the 1960s we get a glimpse into the early history of AIDS.

What I saw was a small and stature, very wasted young man with covers up to his neck lying there in the room with a number of people around him.

That's all coming up later in the podcast. But we begin with the story of two brilliant scientists, each experts in their different fields, who ended

up speaking with one voice, literally. This is the story of Dennis Clat, the speech synthesis

pioneer, who gave his voice to the British astrophysicist

Stephen Hawking, who used computerized speech from 1985 onwards.

Rebecca Kresby reports. I should explain that I communicate with the help of a computer and a speech

synthesizer. This allows me to select words from lists on the screen by pressing a switch in my hand.

When I have built up a sentence, I can send it to the speech synthesizer.

In his later years, Professor Stephen Hawking's voice became almost as famous as his

groundbreaking theories on quantum physics and black holes.

Diagnosed with motor-neuron disease as a student in his 20s,

Hawking was advised that he probably only had a couple of years to live,

defying the odds he lived into his 70s,

but an emergency trackiotomy in 1985 meant he totally lost the ability to

...