Opinion: The top 10 products of the past 40 years

Forty years: Thousands of IT products. Many of them made a huge difference for technology professionals, and they're fondly remembered. But only a few truly transformed IT - and how IT people, users and businesses did their work. Here are 10 IT products that changed everything:

• IBM System 370: In 1964, with its System 360 mainframe, IBM promised that customers wouldn't have to rewrite their software when they bought the next version of the machine - it would be compatible. That was a revolutionary concept. In 1971, the S370 kept that promise and, in the process, sealed the doom of IBM's mainframe competitors. Of course, that never-have-to-rewrite compatibility also created the Y2K problem.
  
• Ethernet: It bubbled up out of Xerox PARC, became a standard in 1980 and soon overran proprietary protocols to become the overwhelmingly dominant networking connection for PCs and servers.
  
• IBM Personal Computer: In 1981, the PC transformed the desktop computer from something users smuggled in (the Apple II running VisiCalc) to a corporate IT standard. It also gave users control over their computing that they would never give up.
  
• Apple Macintosh: In 1984, the Mac transformed users' expectations of how friendly computers should be. The result: mice, graphical interfaces, plug-and-play peripherals and a knockoff from Microsoft called Windows.
  
• SAP R3: Remember when data processing departments built their own financial accounting software? Starting in 1992, SAP AG wiped out the need to maintain all that code - and it was Y2K-compliant, too.
  
• Salesforce.com: Software as a service proved out. If SAP offered "buy instead of build," in 1999 Salesforce.com offered "rent."
  
• Linux: And if Salesforce.com is "rent," Linux is "get it free." More important, since first appearing in 1991, Linux has shown that major pieces of IT infrastructure can be developed by large groups of loosely organized programmers.
  
• Netscape Navigator: It wasn't the first popular Web browser - that was NCSA Mosaic. But when Mosaic creator Marc Andreessen added cookies in 1994, Netscape turned the Web into a worldwide marketplace.
  
• Dynamic RAM: IBM invented it, but Intel Corp. sold the first commercial DRAM in 1970. Within two years, it was outselling the magnetic core memory that had been the standard since the 1950s. And unlike core memory, DRAM was subject to Moore's Law: Over time, it just got cheaper and more plentiful.
  
• Blackberry: The cell phone meant users could always be connected, but starting in 1999 with Research In Motion Ltd.'s Blackberry, users would always be connected to their e-mail - and the era of the 24x7 knowledge worker truly arrived.

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