If your dad’s new 4TB EHD (external hard drive) has been formatted in FAT32 or exFAT, then both his PC and your Mac should be able to read it. Hard drives will have to double in size another seven times to reach that. In theory, this can handle drives up to 64 zettabytes, though 512TB is the recommended maximum. However, hard drives keep getting bigger - now they are typically 500GB to 4TB - and in 2006, Microsoft released a new extended version, exFAT.

In 1996, Microsoft introduced FAT32 to handle much larger hard drives, and FAT32 is still in common use. When DOS was born, popular hard drives only had 5MB or 10MB of storage space, which you could fill today with a single animated GIF. Most operating systems can read files in these old formats. They tend to use a version of Microsoft’s FAT file format, which dates back to the MS DOS (or IBM PC DOS) operating system used by the IBM PC in 1981. Macs and Windows machines do have their own preferred file formats for internal hard drives, but external hard drives don’t always ship with these pre-installed. The hard drives should not be a problem, unless your computers are very old. However, my Mac doesn’t recognise his hard drive, and his PC won’t recognise my hard drive. I bought a 4TB hard drive for my dad, and thought it would be easy to copy the files over so he could use them on his PC. I have a Mac and an external hard drive that includes some important family files.