It's a question many of us have pondered, especially when upgrading our tech: can that trusty old iMac, perhaps a late 2013 model or even an earlier one, be repurposed as a display for a shiny new Mac mini? The thought of getting more mileage out of our existing hardware is always appealing, isn't it?
For a while there, Apple actually supported this very idea through something called 'Target Display Mode.' It was a neat trick that allowed certain iMac models to act as external monitors for other Macs. However, like many things in the fast-paced world of technology, this feature came with some pretty specific requirements, and it's not universally applicable anymore.
Here's the nitty-gritty: if you're hoping to use an iMac as a monitor, especially for a newer Mac like the M1 Mac mini, you're likely out of luck. The consensus from discussions and Apple's own documentation points to a rather strict cutoff. Generally, the last iMacs that could function in Target Display Mode were discontinued around October 2015. If your iMac is newer than that, it's pretty much a no-go for this specific purpose.
Even for those eligible older iMacs, it wasn't a simple plug-and-play situation. There were quite a few hoops to jump through. For instance, the iMac itself needed to be running an older operating system, typically macOS High Sierra (10.13) or earlier. If your iMac was already updated beyond that, finding and installing High Sierra could become a bit of a quest in itself, though workarounds do exist if you're feeling adventurous.
And it wasn't just the iMac that had to be 'old.' The Mac you wanted to connect to the iMac-as-monitor also needed to be from a specific era – generally 2019 and earlier models qualified, and they too had to be running a compatible, often older, operating system. So, the idea of using a brand-new Mac mini with an older iMac as its screen, while intuitively appealing, runs into these compatibility walls.
What about using it as an external hard drive too? That's a separate capability. While using an iMac as a monitor has these strict limitations, its internal storage can often be accessed by another Mac if you connect them appropriately, sometimes via Target Disk Mode (which is different from Target Display Mode) or by using it as a network-attached storage device. However, doing both – acting as a monitor and an external hard drive simultaneously for another computer – is where things get even more complicated and, for most modern setups, simply not feasible.
So, while the dream of giving your old iMac a dual-purpose life as a monitor and hard drive for your new Mac mini is a lovely one, the reality is that Apple's support for using iMacs as displays has largely phased out. It's a bit of a bummer, but it's good to know the technical reasons behind it. Your older iMac might still have value, but perhaps not in the way you initially hoped for this specific setup.
