[twowheels]

I'm not an Apple developer, but AFAIK iOS isn't a true real-time OS in the normal sense (like QNX). That said, the Mach kernel does support real-time priority for threads for applications that require it, but I'm not sure whether this extends to iOS, but I assume that it does.

I'm very happy with the audio performance on my iPad. Answering the question of those who wonder if 500ms would really matter, here's how I use it:

I have a app called Home Concert Xtreme that can take a MIDI music file and display the sheet music. I connect it to my digital piano via USB (with the camera connection kit) and it then allows me to select which parts I will play and which parts it should play. Since my piano doesn't have samples for many instruments, some instrument parts play using the samples built into the app. In addition to following along with the other instruments, when I am learning a new song I might choose to play the right hand myself and have the iPad send instructions to my piano for the left hand part. If these other instruments or the left hand parts were 1/2 second behind it would be EXTREMELY DIFFICULT to keep up with the music!

Going back to the example given previously... 1/2 second *IS* a very long time. If the player controlling the iPad is playing along with the rest of the band it would sound very awkward if they were that far behind. As a software developer I spend a lot of time worrying about delays and I have seen introduction of sleeps < 1/4 second that were visually extremely annoying.