The custom A4 processor in the iPad is in reality a castrated Cortex A8 ARM design, say several sources.
via Apple A4 processor really stripped-down Cortex A8? | Electronista.
This is truly interesting, and really shows some attempt to optimize the chips with ‘known’ working designs. Covering the first announcement of the A4 chip by Brightside of News, I tried to argue that customizing a chip by licensing a core design from ARM Holdings Inc. isn’t all that custom. Following this Ashlee Vance wrote in the NYTimes the cost of development for the A4 ‘could be’ upwards of $1Billion. And now just today MacNN/Electronista is saying Apple used the ARM A8. By this I mean the ARM Cortex A8 is a licensed core already being used in the Apple iPhone 3GS. It is a proven, known cpu core that engineers are familiar with at Apple. Given the level of familiarity, it’s a much smaller step to optimize that same CPU core for speed and integration with other functions. Like for instance the GPU or memory controllers can be tightly bound into the final CPU. Add a dose of power management and you got good performance and good battery life. It’s not cutting edge to be sure, but it is more guaranteed to work right out of the gate. That’s a bloodthirsty step in the right direction of market domination. However, the market hasn’t quite yet shown itself to be so large and self sustaining that slate devices are a sure thing in the casual/auxiliary/secondary computing device market. You may have an iPhone and you may have a laptop, bu this device is going to be purchased IN ADDITION not INSTEAD OF those two existing device markets. So anyone who can afford a third device is probably going to be the target market for iPad as opposed to creating a new platform for people that want to substitute an iPad for either the iPhone or laptop.