In January, Sun announced plans to halt work on the x86 (Intel instruction set) version of Solaris 9, focusing instead on developing the operating system only for its own UltraSPARC processors.
The move triggered a rash of complaints from Sun's user base, which included several advertisements in major newspapers calling for Sun to explain the move in a public forum.
Sun declined those challenges but reversed its stance on the x86 version of Solaris in October by announcing that it would bring the OS back with full support.
"We've had some issues in the past about our commitment to this product," said John Loiacono, vice-president of operating platforms at Sun. "Well, now we are jumping in with two feet. You are going to see over the next two to three months additional enhancements to Solaris as a whole, which will have Solaris x86 as a key component."
Sun posted the download at www.sun.com/software/solaris/, charging users $20 for the software. The company will follow up the early access version with a completed release of Solaris 9 x86 in December. It will probably charge $99 (£63) for a single-processor licence, according to Loiacono.
Users can run Solaris x86 on a wide range of Intel-based hardware, from servers to laptops. In addition, Sun sells its low-end Sun LX50 server with either Solaris x86 or Sun Linux.
The company may also begin to offer more of its systems with Solaris x86 as an option. Loiacono hinted that the OS might next appear on Sun's blade servers, which have yet to be released. Sun will also begin moving on to the x86 platform more of its Sun Open Net Environment (ONE) software, which includes an application server and directory server.
"You will see us make releases for Solaris x86 that [match] the schedule of releases for Solaris on UltraSPARC," Loiacono said. "We are also working to do performance testing and tuning, not just putting bits out there."
A number of companies use Solaris x86 in their production environments. The OS is also popular in academic settings as an alternative to Linux or Microsoft's Windows.
Analysts said the availability of Solaris on Intel hardware provided users with a lower-cost way to use the OS than buying UltraSPARC-based hardware.