Connect Mac Pro OS 10.4 to Mac OS 15.7.2

If you are talking about a Mac Pro desktop minitower, the only two models of that could run any version of Mac OS X 10.4 (Tiger) were the first two Mac Pros.

Neither of those can run anything higher than Mac OS X 10.7.5 (Lion).

Lion is so old that its version of Safari doesn't know how to handle the form of https security that most modern Web sites use. I would not be surprised if Lion also had problems connecting to the Mac App Store. As for iCloud, it now requires macOS 10.13.* (High Sierra) or later, and so does not support Lion.

System requirements for iCloud - Apple Support

So you may have an "interesting" time getting a Mac Pro that old, to work with another Mac which is running macOS 10.15.7 (Catalina).

If you are asking about File Sharing, it may or may not work. If you want to give it a try, however, you will need to set both Macs to use SMB, not AFP. AFP was the default sharing protocol in the OS X Tiger (10.4) era but it was deprecated in macOS Sequoia (macOS 15.5). Even with SMB, however, there may be problems as SMB changed significantly over time (the two Macs may not talk the same version of SMB). All you can do is try it.

applemasher wrote:

Can I connect my Mac Pro OS 10.4 to my Mac OS 15.7.2?

To what end? What do you wish to accomplish by doing it?

Data recovery or transfer?

1) Target disk mode was via FireWire at the time. Your Catalina Mac hardware might still support that. You didn't post exactly what Mac that is.

Transfer files between two Mac computers using target disk mode - Apple Support

2) Remove the drive(s) and connect to your Catalina Mac via a drive adapter cable, something similar to this:

SATA/IDE/PATA to USB 2.0 Adapter - Newegg.com

I appreciate how our friend @Servant of Cats expressed it; "...you may have an 'interesting' time getting a Mac Pro that old, to work with another Mac...'

They aren't wrong.

applemasher wrote:

One is an old Mac Pro G5 running on OS10.4 with 4 drives ... Also on the network is a Mac Pro from 2010 with OS 10.13 I think that is High Sierra that machine works well with the IMac 2020 running Sonoma and does file sharing fine .

The G5 running 10.4 should be able to File Share with the High Sierra machine using AFP.

Also, as I believe the Power Mac G5 used SATA drives, you might consider removing the drives and putting them in an external enclosure. Just make sure the enclosure is backward-compatible with SATA-I (1.5Gbps).

Kudos to you for having a 20-year old Mac that is still running. But as you must be aware, it is long past the time to retire that machine. And if the drives are also that old you should back them up on newer media asap; they should not be trusted any longer.

Servant of Cats wrote:

So you may have an "interesting" time getting a Mac Pro that old, to work with another Mac which is running macOS 10.15.7 (Catalina).

My mistake. You wrote 15.7.2. That's Sequoia – which makes the gap even larger!

applemasher wrote:

One is an old Mac Pro G5 running on OS10.4 with 4 drives

FYI, Apple never made a PowerPC-based Mac called a "Mac Pro". In the PowerPC days, a G5-based minitower would have been called a "Power Mac G5", possibly with a suffix identifying its hardware model year.

With Mac notebooks, the PowerBook name does not refer exclusively to PowerPC-based Macs. It goes back to the 68K era, and possibly is a play on Alan Kay's early vision of a "DynaBook" – a vision that no doubt inspired later work on Macs and iPads. However, Apple dropped all of the "Power" names when they switched to using Intel processors in 2006.