There's a number of additions in iOS 4.3 beta 1, and Mike
have covered in previous posts: improved AirPrint, support for the VeriPhone "Personal Hotspot" feature, new gestures. There are, however, also a couple of notable subtractions: support for the iPhone 3G and iPod touch 2G. Though it's not known at this time whether the ultimate release version will support the older devices, it's a sign that we're nearing end-of-life for them. At the same time, there are new device identifiers in the code, presaging next-generation iPhones and iPads.
The iPhone 3G, released in 2008, had the same Samsung S5L8900 RISC SoC 620 MHz processor (underclocked to 412 MHz) as its predecessor, the original iPhone. And though the first-generation iPod touch shares this hardware platform (the 2G has a slightly speedier ARM11 chip), iOS 4.0 was not supported for that model, or for the original iPhone, when it was released. Though the identical iPhone 3G and iPod touch 2G were supported, iOS 4.0 ran very poorly on those devices, with improvements in iOS 4.2 marginally improving performance for some users. The fact that Apple decided to include support for newer devices and leave it out for older devices with the same hardware suggests a marketing decision rather than an engineering one. Apple didn't want to face user outrage by releasing a firmware upgrade that left out devices only two years old. As it turned out, they ended up dealing with a lawsuit
about that anyway.
There are identifiers in the new beta for iPhone4,1 and 4,2 as well as iPad2,1 iPad2,2 and iPad2,3. The original 2007 iPhone is 1,1, and the iPhone 3G is classified as 1,2, reflecting the fact that it's the same hardware platform with a slight modification (the 3G radio). The iPhone 3GS, with its improved CPU and RAM, is classified as 2,1, and the iPhone 4 is 3,1 (the Verizon iPhone is 3,2). The iPhone4,x and iPad2,x identifiers, then, suggest a significant hardware revision for the next models. Rumors have long suggested
that the next generation iPhone and iPad will sport faster processors like the ARM Cortex-A9, and so the decision to cut off support for older CPUs makes sense as iOS finally moves into multicore architecture. Whether iOS 4.3 will simply not run on these devices, or merely continue to support a reduced feature set, remains to be seen.