Good news, Mac guys and gals! If your Mac is OS X Mountain Lion or Mavericks compatible, then your Mac can also run OS X 10.10 Yosemite, meaning most Apple logo’d desktop computers from 2007 and newer are good to go:
OS X 10.10 Release Notes
OS X 10.10 Developer Preview 1 is pre-release software. Do not use this pre-release software in a commercial operating environment or with important data. You should back up all of your data before installing this software and regularly back up data while using the software.
If an installation of OS X 10.10 Developer Preview 1 fails, try using Disk Utility from a Recovery HD to repair the disk.
This build is being provided to you for testing and development purposes. Should you encounter any problems, submit a bug report using the online Bug Reporter at http://bugreporter.apple.com/. Please make sure to include 10.10 (14A238x) in the bug title and description. This information will ensure that your bug is processed quickly.
When submitting a bug report, make sure to include a Summary, Steps to Reproduce, Expected Results, Actual Results, and the diagnostic output generated by running sudo sysdiagnose in Terminal, or use the special key chord Control-Option-Command-Shift-Period.
For complete instructions on submitting bug reports, visit the Bug Reporting page at http://developer.apple.com/bugreporter/.
OS X 10.10 Installation
Migration Assistant may hang while transferring your information from a Time Machine backup. To proceed with the login, quit the Installer.
Developer Preview 1 may be unable to install over an encrypted volume.
Choosing a later installation from the Software Update notification may fail to install selected updates.
The system may appear to hang if the Login password does not match the OpenDirectory or keychain password. Pressing the Esc key will allow the login to proceed.
— Some all day events may not be displayed. Navigating to a different day, and back will display the missing events.
— Some apps that use Handoff will mistakenly show as Safari in the iOS lock screen and OS X Dock.
— In some cases, not all devices associated with an Apple ID will pair successfully. These devices will be unable to use Handoff, Phone calls, or Instant HotSpot.
— When using a Mac, Handoff may sometimes stop showing icons on other iOS and OS X devices.
— Handoff-based Bluetooth connections between devices may stop working after trying to use Handoff.
— In some cases, using Handoff with Safari will result in an old URL being resumed instead of the current URL.
— Directions and Navigation in Maps does not work with Handoff in Developer Preview 1.
— Phone calls to and from the Mac may sometimes not complete or send and receive audio.
— Dictation shortcut text field is missing from Dictation preferences.
Opening the Customize Commands of the Dictation preference panel may cause System Preferences to hang.
— ShareKit extensions may crash when the Share sheet is closed.
— Finder Sync extensions may not function correctly.
— Shared purchase history page on Mac App Store and iOS App Store are disabled.
— Viewing of Family purchases is not available in Developer Preview 1.
— Items already owned by family members must be re-downloaded from the Purchased page (not Store pages) to get them free of additional charge. .
— Under 13 account creation is disabled in Developer Preview 1.
— While using the iTunes Store you may experience a spinner that never completes. Log out and back in to iTunes to correct the issue.
— Email invitations are not enabled; members can join using push notifications or via inline password entry flow.
— Notifications for “Ask to Buy” are not available on older clients. After parental approval, kids will have to reinitiate the purchase.
— You can’t approve an “Ask to Buy” request from the requestor’s iOS device.
— Streaming video from iCloud may present a black screen. Downloading the video will allow playback.
— Some graphical corruption may be visible when using Icon View in Finder.
— iCloud Documents & Data created with Developer Preview 1 will be deleted from the servers at some point during the beta period. Your devices using Developer Preview 1 will maintain copies of those deleted iCloud Documents & Data. After the server deletes that data, all iCloud Documents & Data you previously used on OS X v10.9 and earlier or iOS 7 and earlier will be copied on the server over to the OS X v10.10 / iOS 8 version of iCloud Documents & Data. Your devices using Developer Preview 1 will then re-upload their copies to the servers. If you delete those copies on your Mac before they are uploaded to the servers, and if you don’t have a backup of them, those documents will be lost. Documents and data managed on earlier releases of OS X and iOS will not be affected by any of this.
— The Web UI for managing iCloud Documents & Data does not show the documents and data managed by systems running Developer Preview 1. Documents and data synced with previous operating systems will be displayed.
— Changes to iCloud Documents & Data in Pages, Numbers, and Keynote on Macs using OS X 10.10 Developer Preview are only available on other devices using OS X 10.10 Developer Preview or iOS 8.0 beta. Any changes from devices using earlier versions of OS X or iOS will not be available. Changes will also not be visible in Pages, Numbers, and Keynote on iCloud.com.
— Some account password prompts may request the same login information several times before dismissing.
— Finder may spin after adding a large number of items to iCloud Drive.
— iCloud settings for My Photo Stream and Shared Streams will be preserved from earlier versions of OS X on upgrade to Developer Preview 1. However, turning off Shared Streams will turn off My Photo Stream, and visa versa.
— Turning off My Photo Stream or Shared Streams may not be available in System or Application preferences after upgrading to Developer Preview 1.
— Mail may not be able to set up new Mail accounts within the Mail application.
— The Markup Signature panel may not detect touchpad events.
— Markup Annotations cannot be modified after clicking Done.
— The markup panel may not display toolbar when invoked.
— Old iMessages stored on your computer are incorrectly deleted when upgrading to OS X 10.10 Developer Preview. Backup your Messages in ~/Library/Messages before upgrading.
— Video Recordings of attached iOS devices running iOS 8.0 beta 1 may flicker and have audio/video timing issues.
— The Remote Desktop Admin Application may be unable to download client installers.
— Apple Remote Desktop feature Changing Client Settings is not supported for Developer Preview 1.
— Some panels and buttons may not be accessible or operate as expected.
— Subpixel rendering is now on by default for all web content. Web sites or in-app web views with extremely tight design constraints may render differently.
— Typing a partial site name and pressing Return can cause navigation to a search engine result page instead of the expected navigation to a commonly visited website identified as a Top Hit.
— Typing a multi-word search term and pressing Return can cause inadvertent site-specific searches instead of the expected web search engine search result page.
— The selected tab when searching for an iCloud tab from another device may not be the tab opened.
— Smart Search Field stop/reload button, one step button, and other smart search field controls are not accessible.
— Using Safari Test Drive on multiple systems which are configured to sync Chrome or Firefox bookmarks to Chrome/Firefox cloud-based sync services may cause duplication of bookmarks.
— Date & Size limits set in Safari are not enforced in Developer Preview 1.
— Safari may stop responding while loading video when playing Netflix content.
— When changing languages while playing Netflix content, it may take several seconds for the audio to switch to the new language.
— Keystrokes may trigger alert sound when in Netflix full-screen playback mode.
— Systems running Developer Preview 1 may be unable to connect to share points over SMB.
— Systems with earlier versions of OS X may not be able to connect to a server running Developer Preview 1 over SSL.
— In Developer Preview 1 unsigned or improperly signed kexts will not be loaded. To use unsigned kexts during development, this strict check can be disabled by adding a “kext-dev-mode=1” boot arg.
— AVFoundation changes the way some ID3 metadata values are represented as AVMetadataItems for binaries that are linked with the Developer Preview 1 SDK.
— Installing kernel extensions on systems running Developer Preview 1 may make your system un-bootable. To fix the issue, boot into the Recovery Partition and run the following:
touch /Volumes/<10.10 Partition>/System/Library/Extensions
kextcache -u /Volumes/<10.10 Partition>
— Some Apple Script Editor toolbar buttons may not enable/disable properly. The menu items can be used instead.