Apple has, as promised, opened up a pre-release version of its forthcoming Mac OS X 10.10 Yosemite software to Mac users who signed up to beta test the operating system.

Just yesterday the firm encouraged those outside the developer community to sign up for the public tests, with the first million sign-ups gaining access ahead of the expected October roll out.

Successful applicants who registered can log into Apple's beta testing site using their Apple ID to gain a redemption code for the Mac App Store.

At the time this article went live the beta site was down for updates, which may mean Apple has been overwhelmed by the demand or it has already filled all of the available slots for the scheme.

Proceed with caution

Apple is advising those who gain access, to install Yosemite beta onto a secondary Mac, currently running Mavericks, or at least to make a time machine back-up of their current state before doing so.

Early reports suggest the operating system is already pretty solid, but bugs could cause programs to crash and various areas of the software to act in unexpected ways. Other areas, designed to work closely with iOS 8, will also not be functional at this time.

Have you downloaded the beta yet? Let us know your thoughts below. If not, check out our early hands on with Mac OS X 10.10 Yosemite.