Hi:
have an old iMac 27 inch late 2009 at present running macOS Sierra with a mini display port at the back that supports output and input from external display port sources. Can I using this large screen as a 2nd display for my MacBook currently using macOS Sonoma through a USB C to mini display port cable?
MacBook Pro 16″, macOS 14.0
Unfortunately, that setup is not supported by Apple. The iMac cannot be used as a monitor for any of the newest Macs and Target Display mode is no longer a feature of macOS, having been deprecated several years ago.
Please see: Use your iMac as a display with target display mode - Apple Support
Per the link above:
• Your target iMac (monitor) must be using macOS High Sierra 10.13.6 or earlier.
• In all cases the source Mac that you're connecting FROM must have been introduced in 2019 or earlier and have macOS 10.15 Catalina or earlier installed.
You might consider a third-party solution, for example: Luna Display or Duet Display, though I can’t speak for the performance of those.
Do yourself a favor, avoid the headache and just budget an extra $100 for a monitor. Yes, they are that inexpensive.
Unfortunately, that setup is not supported by Apple. The iMac cannot be used as a monitor for any of the newest Macs and Target Display mode is no longer a feature of macOS, having been deprecated several years ago.
Please see: Use your iMac as a display with target display mode - Apple Support
Per the link above:
• Your target iMac (monitor) must be using macOS High Sierra 10.13.6 or earlier.
• In all cases the source Mac that you're connecting FROM must have been introduced in 2019 or earlier and have macOS 10.15 Catalina or earlier installed.
You might consider a third-party solution, for example: Luna Display or Duet Display, though I can’t speak for the performance of those.
Do yourself a favor, avoid the headache and just budget an extra $100 for a monitor. Yes, they are that inexpensive.
MacBook Pro 16’’ to iMac late 2009 27’’
