OS X 10.9 Build Number Suggests Extensive Internal Development

While many had expected Apple to follow last year's pattern and release a developer preview of OS X 10.9 early this year ahead of a summer public launch, the company has so far remained essentially silent about its plans for its next-generation Mac operating system. That silence does not, however, mean that Apple has not been working hard on the project since it first started showing up in web logs last fall.

As spotted by an AppleInsider reader, circumstantial evidence of Apple's work showed up in a WebKit bug report early last month revealing that version of OS X 10.9 in testing was Build 13A451. According to Apple's build number scheme, "13" refers to OS X 10.9, "A" refers to the 10.9.0 version, and "451" is part of a sequential numbering of compiled builds.

federighi_wwdc_mountain_lion

Apple Senior Vice President Craig Federighi introducing OS X Mountain Lion at WWDC 2012

AppleInsider speculates that the relatively advanced "451" build number as of early May could indicate that Apple would be able to deliver a fairly mature version of OS X 10.9 to developers at its Worldwide Developers Conference next week, although there is no formal evidence for such a claim.

OS X Mountain Lion's initial developer preview arrived as Build 12A128p in February 2012, with Apple releasing several additional builds to developers before releasing it to the public as Build 12A269 in July of that year. OS X Lion apparently spent a longer time in overall development but a similar amount of time in developer testing, beginning developer seeding with Build 11A390 in February 2011 before being launched to the public as Build 11A511 roughly five months later.

Apple had indicated when it launched its first developer preview of OS X Mountain Lion last year that it was shifting to a more rapid yearly development cycle for OS X in order to bring more features to consumers more quickly. But with Apple yet to have begun seeding developers with versions of OS X 10.9 and the company reportedly having pulled engineers from OS X to work on iOS 7, there have been some questions about how closely Apple will be able to stick to its yearly release plan.

Top Rated Comments

Mad Mac Maniac Avatar
103 months ago
Wait... so they've been working on OS X 10.9 this ENTIRE TIME?! I thought they just looked at their watches, said "Crap WWDC is in like 3 weeks!!", and then threw some code together.... :rolleyes:
Score: 37 Votes (Like | Disagree)
Chaszmyr Avatar
103 months ago
I'm really not even looking forward to this at all. OSX announcements used to be exciting, but newer features like Launchpad and Mission Control do not add anything to my experience whatsoever. Even the under the hood improvements rarely seem particularly interesting anymore. I still get every new version, but that's mostly because I feel forced to for compatibility reasons.

Honestly, without a fundamental change to the way the computer works (something one might expect in an OSXI, not an 10.9), I don't even know what features I would like them to add anymore.
Score: 22 Votes (Like | Disagree)
HussamRaed Avatar
103 months ago
Score: 21 Votes (Like | Disagree)
Four oF NINE Avatar
103 months ago
Release it at WWDC. Screw the developers!
That's a really bad idea
Score: 20 Votes (Like | Disagree)
TimUSCA Avatar
103 months ago
I'm really not even looking forward to this at all. OSX announcements used to be exciting, but newer features like Launchpad and Mission Control do not add anything to my experience whatsoever. Even the under the hood improvements rarely seem particularly interesting anymore. I still get every new version, but that's mostly because I feel forced to for compatibility reasons.

Honestly, without a fundamental change to the way the computer works (something one might expect in an OSXI, not an 10.9), I don't even know what features I would like them to add anymore.

Personally, I consider full-screen apps and Mission Control to be a huge difference in the way my computer works. Just because you don't use these features doesn't mean lots of others don't. For me, it's completely changed the way I use OS X.
Score: 20 Votes (Like | Disagree)
camnchar Avatar
103 months ago
Be prepared to be amazed with over 200+ new features, again

Only 1 of which you'll ever actually use.
Score: 18 Votes (Like | Disagree)

Top Stories

samsung experience 1

Samsung's 'iTest' Lets You Try a Galaxy Device on Your iPhone

Thursday April 8, 2021 12:42 pm PDT by
Samsung has launched "iTest," an interactive website experience that's designed to allow iPhone users to test out Android on a Galaxy device, or "sample the other side," as Samsung puts it. Subscribe to the MacRumors YouTube channel for more videos. The iTest website is being advertised in New Zealand, according to a MacRumors reader who came across the feature. Visiting the iTest website on...
sonny 2021 ipad mini pro dummies

Leaked Dummy Units Show iPad Mini 6 With Thick Bezels and Home Button, New iPad Pro Models

Thursday April 8, 2021 2:11 am PDT by
Rumors suggest Apple will release refreshed versions of the iPad mini and iPad Pro models in the first half of this year, potentially as soon as this month, and a new leak today has provided us with a possible preview of what to expect in terms of the devices' overall design and camera prospects. Tech leaker and Apple blogger Sonny Dickson this morning shared images on Twitter showing dummy ...
fake airpods 3

Counterfeit 'AirPods 3' Hit the Market Prior to Official Announcement

Friday April 9, 2021 2:45 am PDT by
Apple is expected to launch the third iteration of AirPods in the third quarter of this year. Rumors and reports suggest the new AirPods will feature an updated design more in line with the AirPods Pro, but lacking in "Pro" features such as active noise cancellation. Despite AirPods 3 not yet being officially announced by Apple, counterfeit products of the unreleased earbuds have already hit ...
iMessage Android featured

Apple's Rationale for Not Bringing iMessage to Android Revealed in Legal Documents

Friday April 9, 2021 2:22 am PDT by
It's no secret that Apple sees iMessage as a big enough selling point to keep the service exclusive to Apple devices, however new court filings submitted by Epic Games in its ongoing lawsuit with the company reveal just how Apple executives have rationalized their decision not to develop a version of iMessage for Android. Apple clearly recognizes the power that iMessage has to keep users...
nba tracking prompt orange

Two-Thirds of iPhone Users Expected to Block Ad Tracking

Friday April 9, 2021 7:19 am PDT by
As many as 68 percent of iPhone users are expected to deny advertisers permission to track them thanks to Apple's App Tracking Transparency feature, in what is beginning to look like a significant blow to the advertising industry (via AdWeek). With the launch of iOS 14.5, apps will have to receive explicit user permission before accessing an iPhone's advertising identifier or IDFA, which is...
iPhone 13 Battery Life Feature

DigiTimes: iPhone 13 Pro Models to Feature 120Hz ProMotion Refresh Rate and 15-20% Less Power Consumption

Friday April 9, 2021 12:52 am PDT by
The two premium "Pro" models of the upcoming iPhone 13 lineup will be equipped with a low-power LTPO display, enabling the iPhones to have a 120Hz refresh rate, according to industry sources cited by Taiwanese publication DigiTimes. According to today's paywalled report, Apple suppliers Samsung and LG Display are in the process of converting parts of their production capacity to produce LTPO ...
ehric

iPhone 12 Mini Missing From Top 5 Best Selling Smartphone List of January 2021

Friday April 9, 2021 4:58 am PDT by
According to market data compiled by Counterpoint Research, Apple's smallest iPhone since the 2016 iPhone SE, the iPhone 12 mini, struggled to obtain a spot in the top five list of best-selling smartphones in January of this year. According to the market data, the iPhone 12 mini came in eighth place for the best-selling smartphone worldwide in the first month of the year. However, the iPhone ...
Top Stories 56 Feature

Top Stories: 'Find My' Expansion, iPhone 13 Pro Mockup, Largest-Ever iMac?

Saturday April 10, 2021 6:00 am PDT by
Apple's AirTags may still be nowhere to be seen nearly two years after signs of them were first discovered, but Apple this week launched its Find My network accessory program that will let third-party devices integrate with the Find My app on Apple's platforms to make it easy to keep track of your items. This week also saw fresh rumors about the upcoming "iPhone 13" and new iMacs, while...
fortnite apple featured

Epic's Case Against Apple in Australia Might Be Over

Friday April 9, 2021 12:21 pm PDT by
Epic Games and Apple are involved in a highly public lawsuit in the United States, but Epic has also sued Apple in other countries, including Australia, in an attempt to boost its chances of getting a favorable ruling. Things aren't quite going Epic's way, however, as the justice overseeing the case today decided that he's going to let the two companies battle it out in the United States. ...
Apple TV Ray Light Teal Film

Apple Wants to Draw Subscribers to Apple TV+ With More Feature Films

Friday April 9, 2021 10:27 am PDT by
Apple is ramping up its efforts to produce feature films, according to a new report from The Information. Apple has a limited number of high profile films already, including "Palmer," "Cherry," and "Greyhound," and sees it as a way to draw more people into Apple TV+. Apple has been telling studio executives that it is aiming to do more than 10 to 12 original movies per year for Apple TV+,...