Full 64 - chip support got top charge in Steve Jobs ’ Worldwide Developers Conference tonic — it was first on the lean of Leopard enhancements he previewed , ahead even of Apple ’s spectacular Time Machine backup - and - restore technology . Even at a developer conference , however , 64 - chip support was an odd choice for the lead - off position , because it ’s an alternative even Apple hold does n’t yet make sensation for most applications .
How it works
If you ’re pen an app that requires trulyhugeamounts of memory ( more than 4 GB ) or needs random access within data set larger than 2 GB ( as opposed to , for example , video - editing apps that study and compose very large files but employment with only a subset at any one prison term ) , it ’s convenient to allot with 64 turn of data at time , rather than the 32 - number chunks that most of today ’s Mac ( and Windows ) applications use . Apple has for yr extend developers some ways to put to work with 64 - bit data , but those involved working around the fact that the Mac operating system and most of the ironware it ran on were basically a 32 - flake environs
In late years , however , the company has gradually added some verbatim 64 - bit support to its products : the PowerPC G5 central processing unit , for good example , was designed to deal 64 - as well as 32 - bit computer code , and Mac OS X 10.4 ( Tiger ) allow developers to create in full 64 - bit mastery - line or background program , though not 64 - bit programme with their own graphical interface .
What’s changed
Things will be unlike in Leopard : Developers can now build full - fledge Mac apps that are 64 - bit - up to . But developers win over existing Mac programs will front a reasonable bit of work . Not only their own code , but every subroutine library , theoretical account , and plug - in their political platform use will have to be modified and recompiled .
Even then , there ’s not always a clear - turn off typesetter’s case to move to 64 minute . First , 64 - bit code will work only on G5 or Core 2 processors — developers will still have to deliver 32 - bit versions for substance abuser with Macs free-base on G3 and G4 PowerPCs or even with Intel ’s first - contemporaries Core Duo and Core Solo CPUs ( in other words , the current MacBook , MacBook Pro , iMac and Mac mini product lines ) .
secondly , some 64 - spot programs will in reality execute more slowly than 32 - bit equivalent , peculiarly on G5 Macs . Although most applications programme are likely to find fault up some performance by go 64 - mo , the benefits are not likely to be overwhelming , even on the new Mac Pro and future manakin with Core 2 C.P.U. . The independent problem is that go from 32- to 64 - bits result in inflated code , which means less of it fit in the processor ’s L1 and L2 caches , and more relatively dense calls to computer storage are required .
Who’s it for
developer of sure type of programs that do work with huge amount of money of data — some scientific computing lotion , gravid database and data - mining systems , turgid - scale CAD / CAM apps , and specialized look-alike processing programs , to name a few — will apprize Leopard ’s full , aboriginal support for 64 - bit computer science , particularly if they are creating novel coating from scrape and if they are targeting only future Core 2 CPUs , leaving PowerPC and first - propagation Core exploiter behind .
What it means
In a ten or two , 32 - bit computing may only be a distant remembering , and the Mac group O ( or whatever succeeds it ) and the ironware it runs on will be full optimized for 64 - bit surgical operation . By then , in hindsight , the improver of 64 - morsel covering accompaniment in Leopard will count like a milestone on an significant evolutionary itinerary . But in the close terminus , it ’s mostly of interest to developer of specialized technological coating . For most Mac fans — even nontextual matter professionals and other mogul user — this is one spring forward that ’s not likely to produce much of a splash when Leopard is loose next spring .
[ Henry Norr is a former editor ofMacWeekand a former technology columnist for theSan Francisco Chronicle . ]
