Using a 2009 iMac as a second display for a 2017 MacBook Pro


Apple added the ability to use any Mac as a secondary display for any other Mac several years ago.  When I got my MacBook Pro I wanted to try this out, but googling around sowed confusion. The video ports on Macs have changed over the years (Firewire, Mini Display, Thunderbolt, USB-C).  A lot of people commented that various combinations of iMac, MacBook and cable didn’t work for them, so I though I would list exactly what I did and what I used so someone with the same setup could also have success.

  • iMac: Late 2009, 27″ iMac, Mac OS 10.13 (High Sierra)
  • Cable: Monoprice P/N 24447 USB 3.1 Type-C to Mini DisplayPort Cable 4K@60Hz, 6 ft
  • MacBook Pro: June 2017 w/ Touch Bar, Mac OS 10.13 (High Sierra)
  1. MiniDisplay side of cable to iMac, USB-C to MacBook Pro
  2. On the iMac, press Command F2. Both screens go blank, and when it returns, the iMac should now be a secondary display
  3. On the MacBook Pro, go into System Preferences -> Displays -> Arrangement and drag the larger of the two rectangles (representing the secondary iMac display) to a location that mimics where you physically have that monitor positioned





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