What was it like?

I learned my software skills on the Ferranti Mercury computer. It had as I recall 468 words of memory (a word is about 6 bytes so call it 3k bytes).   Let's see, my phone has 8,000,000,000 bytes - that's about 2.5 million times more.  My phone makes the 1500 instructions per second look pretty silly as well.

The computer was big. The electronics used valves and they get hot. So each cabinet has a refrigerating unit built-in, and they were noisy. 

To program this remotely we wrote the programs on paper tape (5 track) and sent it with a teletype machine to operators who would give us a 24-hour turnaround for each test if we were lucky. The program language was Mercury Autocode - which looks a lot like the original BASIC language, if you remember that.

It was the first computer used in CERN  and the main computer used for scientific calculations at my company (ICI). By the time I started it was getting long in the tooth and after a couple of years it was replaced with a KDF9.  That didn't last very long (they apparently only built 29 of them) and we switched to the first IBM System/360 which was a massive change, and set the pattern for many years. 

It was different from a modern computer, but the basic components were really the same. A processor, memory, printer, and external memory all communicated through a bus. All that has really happened in the last 6 decades is that the components all got smaller and faster.  Moore's Law works!

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