The 53-year-old Allchin joined Microsoft in 1990, initially working on the company's networking product strategy. He came from, where he had been the architect of the now-defunct Vines network operating system. At Microsoft, Allchin's main achievement was in leading the development of the Windows operating system.
"When it comes to Windows, the buck stops at Jim," said Michael Gartenberg, an analyst at JupiterResearch. "Allchin has been the guiding father of Windows for many years and had a tremendous responsibility for charting the flagship product for Microsoft."
On Tuesday, Microsoft announced thatat the end of next year, after it ships , the successor to Windows XP. Until then, Allchin will head Microsoft's new Platform Products and Services division alongside his successor, former sales chief , Microsoft said.
But while Johnson has been a star at Microsoft, rising through the sales and marketing ranks, he is not really a replacement for Allchin, said Rob Helm, an analyst at Directions on Microsoft.
"Johnson will occupy the box that Allchin occupied, but he is not a dweeb. He is a very capable manager but not the company's senior technical architect," Helm said. "It was striking to me that Microsoft did not name anyone, really, to replace Allchin. There is a job he did that is currently vacant."
After Bill Gates, Allchin is Microsoft's "most senior geek," Helm said. "He succeeded beyond everyone's wildest dreams, basically putting Novell on the margins of IT with Windows NT," he said. "Microsoft moved from a follower to a leader in the networking area on his watch."
Allchin's departure will be a loss on many levels, said Israel Hernandez, an analyst at Lehman Brothers. "He's had a long history with Microsoft," Hernandez said. "He's gone through practically every major product release with them and was one of their chief architects. He was a key lieutenant under Ballmer and Gates."
Allchin is also known for his strong belief in Windows as the jewel in Microsoft's crown, even during the emergence of the Internet in the mid-1990s. It was Allchin who pressed for the integration of Windows and the Internet Explorer Web browser, while others inside the company argued for a faster and more complete embracing of the Net.
In early 1997, Allchin sent Gates an e-mail titled "Losing a Franchise--The Microsoft Windows Story (a new Harvard case study)," according to the book "Breaking Windows," by author David Bank. Allchin wrote that he was troubled by plans to release IE for other operating systems as well as for Windows. "I consider this cross-platform idea a disease within Microsoft. We are determined to put a gun to our head and pull the trigger." Gates agreed and began to steer the company back towards Allchin's view.
The integration of IE into Windows caused a senior-level shake-up at Microsoft, including the, who had headed development of the Web browser.
The episode is an example of the power Allchin has inside Microsoft, said Rob Enderle, an analyst at Enderle Group. "He was one of the powers in the company. After Gates and Ballmer, he was an easy third--very powerful and very well-liked by most people," Enderle said.
Ultimately, the bundling of IE with Windows led to aagainst Microsoft. Still, Allchin's legacy has to be that Windows today runs on the vast majority of personal computers, Gartenberg of JupiterResearch said.
In his years at Microsoft, Allchin has become known to be open about the company's mistakes. He avoids travel and spends most of his time in meetings, but prefers "think days" in his lab. Typically Allchin works 12-hour days--from 7.30 am until 7.30 pm--at Microsoft's Redmond, Wash., headquarters. His focus is on quality even made it hard for Microsoft to recruit him: "It took a year for me to actually agree to come here, because I did not think the quality was appropriate, and I did not think much of DOS, did not think much of Windows and OS2 was a complete blowout," Allchin said in a recent interview on Microsoft's Channel 9 Web site.
After making sure that Vista hits store shelves, Allchin will likely begin spending his time with his family and his other love: music. He is an avid guitar player and has even shared some of his work on Channel 9, part of Microsoft's online community for developers. Before making it big in software, Allchin was a starving musician eating Cheerios without milk after his food stamps ran out, he told Channel 9 in an interview.
In an, Allchin reminded Microsoft employees that he isn't going away yet. "This is not a retirement announcement e-mail," he wrote. "My intensity will not abate. My commitment to excellence is as strong as ever."
He decided to retire at the end of 2006 after an unspecified medical event led him to evaluate his priorities, according to the e-mail.
"Now...lets's ship, ship, ship!" he closed the message, referring to.
CNET News.com's Scott Ard contributed to this report.