Voices of Science

Well, anything that’s worth doing has its frustrations, doesn’t it? Did you ever come across those nice little pithy sayings by Piet somebody? One of them is, ‘A problem worthy of attack proves its worth by hitting back.’ [Laughs] And it certainly hit back, programming did. Well that was the fun of it. It was so difficult – making it fit the space, because there was so little storage, you had to be so careful. I mean nowadays, when you’ve got megabytes and gigabytes and goodness knows how many bytes, you can’t imagine what it was like when you’ve only got sixty-four 20-bit numbers, that is nothing, it’s nothing, and you have to be very careful. Well one of the things you could do, which you couldn’t do on more sophisticated programs later, you … there were instructions for taking a number from anywhere in the computer, and adding to it. So you could actually alter the – get the program to alter the instructions. Which was good fun, but it made it very difficult to check because you didn’t know quite what the instruction said by the time you got there. [Laughs] Yes, you could be clever that way, you could be very ingenious with altering the instructions, making the program alter itself. It was thought to be unsound. Well risky, you know, made it so difficult to get the program right. And if somebody else was trying to read the programme, they wouldn’t understand it. You have to know where every binary digit is going. You do. Yes, you did, you had to know completely what was going on in the computer. I don’t think you had to understand the – how the valves worked, but you did have to have a good grasp of how the logic went. Well how the additions worked and so on, which was really very detailed.