According to The Korea Herald, Apple (NASDAQ:AAPL) is working on a brand-new iPhone that has support for a digital pen. The new phone, the publication says, could start shipping to customers as soon as 2019 -- or about two iPhone generations from now.

Unlike Samsung (NASDAQOTH: SSNLF), which the report says implements the S-Pen functionality in its Galaxy Note lineup by way of "electro-magnetic resonance technology that requires additional panels under the screen," Apple is apparently trying to implement what is called a supercapacitor stylus "for price benefits."

Apple's iPhone X tilted back with water splashing around it.

Image source: Apple.

While this news is neat, the most interesting tidbit came near the end of the report. One of the sources said that Apple will need to significantly improve the performance of its mobile processor technology to support a digital pen. The source also added that Apple "had to compromise on some touch performance of the latest iPhone X largely due to the less advanced chipset." This is a curious claim that I think is worth exploring further.

What does the A10X have that the A11 Bionic doesn't?

We know that Apple successfully supports a digital pen -- known as the Apple Pencil -- with the latest iPad Pro tablets. With the latest iPad Pro tablets, according to the company, when a user writes on the screen using the Apple Pencil, the screen begins to scan for input at a rate of 240Hz, or cycles per second. This is twice the peak refresh rate of the display (which is 120Hz).

An Apple iPad Pro tilting back on the left, and another iPad Pro tilting backward on the right.

Image source: Apple.

I suspect that upping the rate at which the system scans for touch input requires a fast processor. Since the Apple A10X successfully powers the iPad Pro can clearly handle pen input at an extremely fast rate, we know that A10X-level performance is good enough to handle high-speed touch input.

What's interesting is that the only area where the A10X is faster than the A11 Bionic is in the graphics processing unit or GPU.

I don't think the GPU would directly impact the touch performance of a device, though. It's not as though the GPU in an iPad Pro suddenly starts running at full blast whenever somebody writes on it with an Apple Pencil -- that'd be ludicrous.

So, here's what I think the source cited is really talking about.

Remember the ProMotion display?

Apple reportedly tested a high-refresh rate display on the iPhone X (Apple calls such displays ProMotion displays) but ultimately chose not to ship the device with such a display. Instead, the iPhone X shipped with a display that could only refresh its contents at 60Hz -- half that of the current iPad Pros.

Although I originally thought that Apple scrapped the technology because it may have been too tough to manufacture, another factor could've been that the GPU in the A11 Bionic couldn't keep up with the processing demands a high-refresh rate display without dropping frames.

Indeed, the extra GPU performance that the A11 Bionic chip delivers (Apple claims a 30% boost over the GPU performance in the A10 Fusion) is already offset by the fact that the iPhone X must render a screen with about 30% more pixels than the prior-generation iPhone 7 Plus. Or perhaps the GPU could handle the extra pixels and having to render twice as many frames in each second, but to do so, the GPU would consume too much power for Apple to achieve its desired battery life goals.

Since a faster refresh rate would dramatically improve the smoothness of the user experience, and since a faster display refresh rate would require that touch input be faster to keep up, I think this is what The Korea Herald's source is referring to.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.