Sunday, February 22, 2015

Big Computer -Little Computer

Early in 1963, a  couple of engineers from the recent technology startup company Digital Equipment Corporation (DEC), drove up to Ontario, Canada to visit a nuclear science laboratory at Chalk River.

The scientists at Chalk River wanted a custom digital control system to monitor a nuclear reactor and pass data back to their mainframe computer. The DEC senior engineer, Gordon Moore, realised that rather than building a custom piece of dedicated equipment for the Chalk River Labs, the job could be done much more easily with a very small programmable computer, and so the minicomputer was conceived.

The PDP-5 was a revolutionary design, and a champion of minimalist digital design - yet it still occupied 2 full sized equipment racks - as can be seen from the photo below.

What  the PDP-5 offered for the first time was an affordable computer, and at $50,000, it was a lot cheaper than it's nearest competitor. It was cheap enough to use for scientific monitoring, and as it was fully programmable - could be applied to many different tasks. It could also be used as a data source for a larger mainframe, allowing the mainframe to get on with other tasks whilst the PDP-5 collected data.

This was one of the first examples of what I'll call Big Computer -Little Computer - a combination two machines of widely differing sizes connected together, in order to make a more overall flexible system.

The PDP-5 was by today's standards a very simple machine. In fact a $10 Arduino is many times more powerful than the PDP-5. But, as the predecessor of the renowned PDP-8, which using an instruction set based on that of the PDP-5, launched in Spring 1965, the minicomputer revolution. This led to the start of the microcomputer revolution, about 10 years later, in December of 1974 with the launch of the Altair 8800. The rest, as we say, is history.

PDP-5  c 1963

The Big Computer - Little Computer concept has been exploited many times as a means of achieving functionality that exceeds the "sum of the parts".

Recent Examples.

In October 2011, ARM Holding announced their big.LITTLE heterogeneous computing architecture where relatively low power smaller cores are coupled to larger, power hungry devices, to give an architecture that can respond efficiently to dynamic changes in computing load, than just clock frequency scaling of the larger cores could achieve.

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