2017 MacBook Pro to 2009 iMac TDM cable

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2017 MacBook Pro to 2009 iMac TDM cable

Hi Guys,

I'm based in the UK and having challenges locating a cable to do the following:?:

I have my 2017 MacBook Pro running Ventura 13:7:8 OS and will have access to a late 2009 iMac running High Sierra that I want to use as a display monitor.

Has anyone knowledge of a suitable cable that supports Target Display Mode Please?

I imagine one end would need to be a Mini DisplayPort 4K 60Hz that supports Target Display Mode, with the other end being USB, or Mini Display, which will be used with an adaptor for the MBP USB-C connection, or better still, if there is a cable with a USB-C.

Apparently, according to one specialist supplier, there are several conditions to abide to for the cable to work.

Your 2017 MacBook Pro must be running macOS Catalina (10.15) or earlier. TDM was removed from Big Sur onwards, so if your MBP is on Big Sur, Monterey, Ventura, or later, this simply won't work regardless of cabling.

The late 2009 iMac must be running macOS High Sierra 10.13.6 or earlier You can't use target display mode with later versions of macOS, or with Boot Camp and Windows Apple Support.

Operational notes:

This only works with the 27-inch late 2009 iMac. The 21.5-inch late 2009 model doesn't support TDM at all.

iMac must be powered on and logged in, then press Cmd+F2 (or Cmd+Fn+F2 if function keys are set to standard) on the iMac's keyboard to enter TDM. Apple's own keyboard works most reliably for this.

Resolution will be capped at 2560 × 1440 — fine, but no Retina-style scaling, and modern macOS dropped sub-pixel antialiasing so text won't look as crisp as you might remember.

This is my last option, thanks in advance.....Wayne

MacBook Pro 15″, macOS 13.7

Posted on May 6, 2026 1:26 PM

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Answer 1

May 6, 2026 2:39 PM in response to wjs44

You’re welcome.

Catalina is the last OS to support TDM.

TDM died in hardware with the release of the first Retina Macs in 2014.

The appropriate Thunderbolt cable for this setup with Macs that are compatible can easily run $80 or more.

There is a hardware solution - Luna - but it’s perfornance limited to images that don’t move much, so video motion is out.

Do yourself a favor and forgo the IMac as display and find a proper external display for your laptop. Setup will be dead simple, you won’t blow your budget on special cables that won’t work anyway and a monitor will use much less energy than the old iMac.

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Answer 2

May 6, 2026 4:56 PM in response to D.I. Johnson

D.I. Johnson wrote:

The appropriate Thunderbolt cable for this setup with Macs that are compatible can easily run $80 or more.

A Thunderbolt cable would not be needed for a 27" Late 2009 iMac. That Mac did not support Thunderbolt, and so only needs DisplayPort input (on a Mini DisplayPort connector).

If Apple had not retroactively added restrictions on the video source ("must be a Mac released in 2019 or earlier, running Catalina or earlier"), you'd only need a USB-C to Mini DisplayPort adapter cable or the equivalent. Those are much cheaper and easier to come by than the Thunderbolt 3-to-2 adapter and Thunderbolt 1/2 cable needed for 2011 – mid 2014 iMacs.

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