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The VAX-11/780

A Complete History Of Mainframe Computing
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The VAX-11/780

While most of our readers know that the x86 instruction set originated in 1978 with the 8086, perhaps a more important development happened a year earlier when Digital released the infamous VAX-11/780. But how could anything possibly be more important than the x86 instruction set?

When most people think of DEC, they remember a large mini-computer maker that failed and was bought by Compaq when the micro-computer usurped DEC’s key market. But what happened in 1977 that was so important? DEC’s VAX and its very comely wife, VMS, the latter of which still has much relevance today.

The VAX-11/780 was ostensibly released to address the shortcomings of the highly successful and very well liked PDP-11. DEC downplayed many of the changes and instead focused on the ability to finally break the 16-bit (64 K) addressable memory limitation of the PDP-11 with the VAX-11/780’s 32-bit address. However, there was much more to it than that.

The VAX is considered by most to be the finest of all CISC instruction sets, rivaled only by those influenced by it. It was a highly orthogonal instruction set, with 243 instructions on several basic data types and with 16 different addressing modes. This elegant architecture was a strong influence in the Motorola 68000 family, which became the platform for Apple Lisa and MacIntosh until it was replaced by the PowerPC in the 1990s. Incidentally, the performance of the VAX-11/780 was adopted as a standard measurement when “VAX MIPS,” or later just “one MIPS,” became a measure of computer performance.

However, perhaps the most important contribution of the VAX was VMS. Windows NT was developed by none other than Dave Cutler, the designer for VMS. He was one of many VMS developers who went over to Microsoft to work on the development of Windows NT. Despite the controversy surrounding Windows, Windows NT is still the dominant operating system in use today, and will remain so for the foreseeable future, particularly since Windows 7 is being far better received than Vista. This is not to denigrate the VMS operating system as insignificant other than its impact on Windows NT as it was a much respected design that was especially user friendly.

Many showered accolades on this easy-to-use operating system, which was very much ahead of its time. In fact, although the VAX is dead, OpenVMS is clearly not, and is currently running on Intel's Itanium processors and HP's archaic Alpha processors, with a new release due out later this year. Thus, since its release 32 years ago, the operating system is still going strong.

As delightful as the VAX and VMS were, and the latter still is, they never challenged the Big Blue beast in any real economic way and instead probably helped IBM in its fight with the government, which was not too fond of what they considered IBM's monopoly. In 1981, President Ronald Reagan dropped the anti-monopoly suit against IBM, and that same year, Big Blue released the 3081, which incidentally, was the first mainframe with which I had experience. And what an experience it was.

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