Apple released the latest major update to its desktop operating system, macOS Catalina, on Monday. A lot of Mac owners were enthusiastic about a feature called Sidecar when they went into the upgrade. If you haven't followed Catalina's creation, Sidecar will allow you to use a new iPad with your Mac as a secondary screen.

It's a feature that has been available on macOS for a couple of years now through a variety of third-party apps, but the ability of Apple to deeply integrate Sidecar into macOS, as usual, made the feature even more compelling. Sidecar has only one problem: you're going to need a relatively new Mac and iPad.

Credit: The Verge

Sidecar only operates for Mac laptops and desktops, including a sixth-generation Intel Skylake cpu and newer, according to an Apple white paper found by The Verge. As far as Apple's laptop range is concerned, it just happens that any version that uses a Skylake processor always contains one of the troublesome butterfly keyboards of the business. Specifically, Sidecar fits for MacBooks 2016 and beyond, MacBook Air models 2018 and beyond, and MacBook Pros 2016 and beyond. In other words, when you kept your non-butterfly MacBook keyboard, good luck.

Likewise, mobile support for the app is minimal. You're going to need an iMac in 2015 and later, a Mac mini in 2018, an iMac Pro or the next Mac Pro. It's also worth noting that to take advantage of the functionality you'll need a relatively new iPad. Here, Apple says that using Sidecar requires an iPad with Apple Pencil support and iPadOS 13. The drawback of the app is that you can only use it with two computers that are connected to the same Apple ID. For example, if they are related to different accounts, you can not assume that you can borrow an iPad from a family member.

One hypothesis that describes Sidecar's small number of devices is that the functionality relies on HEVC, a high-efficiency video codec. Beginning with the generation of Skylake, Intel also added enhanced codec support to its CPUs. Even if true, this is still a disappointing limitation as some of the more powerful Broadwell-equipped Macs would probably have been able to handle the feature.

While Sidecar is a bummer that works with so few Macs and iPads, the good news is that there are third-party alternatives that offer the same functionality, as mentioned above. For example, Duet Display works with a much larger range of Macs and iPads. If that's more of your jam, you can even use it with a Windows PC.