I wonder which was the first computer with a real time clock, what year and how it was implemented. I imagine it was invented primarily for charging for computer time. I think the first machine I programmed, the IBM 7094 had one because if your job ran over its limit time (30 seconds IIRC), the job was aborted. Unless that was the operator looking at his wrist watch!

Roger Holmes wrote: I wonder which was the first computer with a real time clock, what year and how it was implemented. I imagine it was invented primarily for charging for computer time. I think the first machine I programmed, the IBM 7094 had one because if your job ran over its limit time (30 seconds IIRC), the job was aborted. Unless that was the operator looking at his wrist watch! Roger Holmes --------------------- The earliest I worked on was the CDC 1604, shipping in 1959. It used a 1ms increment and a 48 bit count. Like you mention, it was used for job control. But most of the early customers were military and used it for data logging from various experiments. That's a nice way of saying they made bombs and exploded them. Billy