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User profile for user: leaus82
leaus82 Author
User level: Level 1
4 points

Dual Screens iMac

I have an old iMac, circa 2011/12. It can no longer be updated, so it's not useful as a stand-alone computer anymore, but I wonder if I can use it with my newer iMac (2017) as a dual screen. I bought a Thunderbolt cable, but this didn't seem to work. Can anyone advise if it is possible and, if so, which cable I need?


The iMac 2011/12 has the following ports on the back;

• Audio line out

• Audio line in

• 4x USB A 2.0 ports

• Firewire 800 port

• 2x Thunderbolt ports

• Gigabit Ethernet Port


The iMac 2017 has the following ports on the back;

• Audio line in

• SDXC port

• 4x USB A 2.0 ports

• 2x Thunderbolt 3 USB-C

• Gigabit Ethernet Port


Any help would be much appreciated.


Thanks


iMac 27″, macOS 10.13

Posted on Jul 13, 2023 1:47 AM

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User profile for user: Servant of Cats
Servant of Cats
User level: Level 6
16,600 points

Posted on Jul 13, 2023 5:21 AM

You may be one of the few people in the world who can still use Target Display Mode. Not that I believe you will want to do so.


Use your iMac as a display with target display mode - Apple Support


A 2011/2012 iMac can act as a TDM display, provided that you make a Thunderbolt connection to it (note: not a Mini DisplayPort one), and that it is running High Sierra or earlier.


The 2017 Mac is old enough that it can use the 2011/2012 iMac as a TDM display – but only at a cost. The 2017 iMacs can run Ventura, but in order to use another iMac as a TDM display, they have to be running Catalina – or earlier. So instead of running a current OS that gets bug fixes, and for which you can still get applications from companies like Adobe and Microsoft, you'd have to intentionally hobble the 2017 iMac with an outdated OS.


To make a Thunderbolt connection between the Macs, you'd need an Apple Thunderbolt 3-to-2 adapter ($50), and a Thunderbolt 1/2 cable ($30 or so). A USB-C to Mini DisplayPort adapter would have plugs that physically matched the connectors on the two machines, but since the 2011/2012 iMac has Thunderbolt, it can only offer Thunderbolt TDM service, not Mini DisplayPort TDM service. If you have a USB-C to Mini DisplayPort cable, it may still be of future use for hooking up a real hardware monitor.


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User profile for user: Servant of Cats
Servant of Cats
User level: Level 6
16,600 points

Jul 13, 2023 5:21 AM in response to leaus82

You may be one of the few people in the world who can still use Target Display Mode. Not that I believe you will want to do so.


Use your iMac as a display with target display mode - Apple Support


A 2011/2012 iMac can act as a TDM display, provided that you make a Thunderbolt connection to it (note: not a Mini DisplayPort one), and that it is running High Sierra or earlier.


The 2017 Mac is old enough that it can use the 2011/2012 iMac as a TDM display – but only at a cost. The 2017 iMacs can run Ventura, but in order to use another iMac as a TDM display, they have to be running Catalina – or earlier. So instead of running a current OS that gets bug fixes, and for which you can still get applications from companies like Adobe and Microsoft, you'd have to intentionally hobble the 2017 iMac with an outdated OS.


To make a Thunderbolt connection between the Macs, you'd need an Apple Thunderbolt 3-to-2 adapter ($50), and a Thunderbolt 1/2 cable ($30 or so). A USB-C to Mini DisplayPort adapter would have plugs that physically matched the connectors on the two machines, but since the 2011/2012 iMac has Thunderbolt, it can only offer Thunderbolt TDM service, not Mini DisplayPort TDM service. If you have a USB-C to Mini DisplayPort cable, it may still be of future use for hooking up a real hardware monitor.


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User profile for user: leaus82
leaus82 Author
User level: Level 1
4 points

Jul 13, 2023 3:42 AM in response to User_-_Name

Thank you for your response. I tried the steps you outlined above, but not having much success.


I have both computers set up for 'screen sharing', but when I go to the 'network' tab, as described above, I do not have the option to click 'share screen' or 'connect as...'. I have attached screenshots, to show you what I am seeing.


Thanks


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User profile for user: User_-_Name
User_-_Name
User level: Level 1
20 points

Jul 13, 2023 2:34 AM in response to leaus82

Hello,


Surprisingly Enough you can do a dual screen from computer to computer, not only that but you can also control the other computer using the other computer, this requires no third-party apps or apps from the App Store in general.


Just go to System Preferences/System Settings > Sharing > "Screen Sharing" and make sure it's ON on BOTH computers, then go to Finder and go to the "Network" tab, click on your computer and then click on "Share Screen" or "Connect As...".


Hope this helped.

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Dual Screens iMac

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