IPhone – ios devices screen overview

According to Apple, (scroll to the bottom of the page) only the two most recent generations of each device can upgrade. So both iPads, the iPhone 4 and 3GS and the 3rd & 4th generation iPod touch. One exception: The CDMA (Verizon in the US) iPhone 4 is staying on 4.2.6 for a while. It has some, but not all, features of iOS 4.3.

That leaves the first two generations of iPod touch and the original iPhone and iPhone 3G unable to use it.

The 3G and second-generation iPod touch got stripped-down versions of 4.0-4.2.1. (No multitasking, homescreen wallpapers, or printing.) The other two devices left out (1st-gen iPod touch & iPhone) didn't even get 4.0.

I am not an engineer [IANAE?], but I have been impressed by the advice of Steve Gibson, www.grc.com, a security researcher who has produced more than 300 consecutive weekly shows for his podcast, "Security Now."

His advice is charge lithium ion batteries early and often.

Two weeks ago he stated it thusly:

STEVE: Yes. Now, the universal agreement is that, unlike prior technologies, prior chemistries, both nickel-cadmium and then nickel-metal hydride, which was actually the same fundamental electrochemistry, those had a memory effect. So if you only discharged them a little bit and recharged them often, they would forget that there was, like, a lot more room down below the point that you were normally starting the recharge. So the logic there was run them all the way down to the ground before you recharge them. And if you can't, then you could reset their memory by deliberately doing some deep cycles.

Lithium-ion, completely different story. It has no memory. And it actually is better for the chemistry not to be running it all the way down. So there the logic is charge often. And if you are in a situation where, for example, you have access to a plug, and you've got your adapter, always use the adapter when you can.

I took this quotation from the transcript of episode 334, available here, on grc.com.

I hope he's right.