Q: strange yosemite experiences

It actually doesn't make much difference what is installed because you will need to wipe the drive anyway because you don't legally own the Yosemite or El Capitan installed on the machine. You will have to completely re-partition the drive and reformat it, then install a version of OS X that you have either purchased or legally downloaded from the App Store using your Apple ID. This goes for any other software that may have been installed by the seller.

However, without knowing the specific model that you purchased I cannot tell you what version of OS X was originally pre-installed on it. If it is a 2011 model or later, then you would do the following:

Install OS X Using Network Recovery

Boot to the Network Recovery Server:

Restart the computer and after the chime press and hold down the COMMAND-OPTION- R keys until a globe appears on the screen. Wait patiently - 15-20 minutes - until the Recovery main menu appears.

Partition and Format the hard drive:

1. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your newly installed hard drive (this is the out-dented entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Apply button and wait until the process has completed. Quit DU and return to the main menu.

Reinstall OS X: Select Reinstall OS X and click on the Continue button. Be sure to select the correct drive to use if you have more than one.

Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.

This should restore the version of OS X originally pre-installed on the computer.

Yes,  you can use Network Recovery per my earlier post. Good luck!

You must be able to boot the computer from a different device than this SSD, otherwise you cannot unmount it in order to partition/format it. If it has a Recovery HD on it then do this:

1. Boot from the Recovery HD
2. Open Disk Utility from the menu
3. Select the indented volume entry from the sidebar
4. Erase this volume (probably named Macintosh HD)
5. Quit Disk Utility
6. Select Reinstall OS X from the menu
   

musophile01 wrote:

 

Cheers Kappy, thanks for the very interesting reply!

 

When I click on the "About This Mac" menu, it comes up with "MacBookPro12,1" which I presume is

the model and the date in which it was first released?  This being the case, I presume that Yosemite

would have been the original OS, if it was sold to me by Amazon as new?

Look up the model on http://mactracker.ca (a handy app) or http://everymac.com

They list the minimum OS for each model.

Apple can ship older models with a newer OS if the model is kept on sale for a number of years. This gives an indication of how long models have been in production…

http://buyersguide.macrumors.com

musophile01 wrote:

 

Thanks Dew Reece and Kappy.

 

Getting a bit worried that I don't have the technical competence to re-install the original OS, but will see if I can work it out.

 

Anyway:-

 

 

Apple can ship older models with a newer OS if the model is kept on sale for a number of years. This gives an indication of how long models have been in production…

http://buyersguide.macrumors.com

 

So it follows that if this model is a "MacBook Pro (Retina, 13-inch, Early 2015), " then it would not be legitimate for Apple to have put

a new OS on it , since the concept of "a number of years" would not apply?

10.11 (El Capitan) was released September 30, 2015…

https://en.wikipedia.org/wiki/OS_X#Version_10.11:_.22El_Capitan.22

That means 10.10 (Yosemite) is considered out of date after October 2015, Apple ship Macs with the newest OS version so that customers think they have the latest model.

It really depends on how long your Mac has been sitting in storage before being sold, you can probably still find this model of Mac with 10.10 installed if you look hard enough. Find a terrible 'PC warehouse store' that keeps old stock around if you really want the old OS on this model. Some stores may have deals that have this model with the old OS.

Apple have become so good at stock management that their devices don't generally stay sitting in storage for too long - you need a retailer that has poor stock management to find an older OS pre-installed on this model.

I don't see very much difference between 10.10 & 10.11 - why do you need Yosemite? I can't think of any software that runs on one but not the other.

As Kappy has detailed Internet recovery should get it back to stock, it isn't clear to me if that means 10.10 or 10.11 in your case.

Seek help at an Apple store if you can't set it up or resolve the failed erase.

musophile01 wrote:

 

@ Kappy  Incidentally, I do notice, when I bring up the recovery (OSX Utilities) screen, that the El Capitan logo appears next to where it says "Reinstall OSX."

Is this something I should just ignore (I mean, is it just used as an example, rather than the actual system), or does it mean it will inevitably re-install El Capitan again, even if I do get it to work?

There are 2 kinds of recovery mode 'Internet' (cmd+option+R) & the 'recovery partition' (cmd+R).

OS X: About OS X Recovery - Apple Support

Internet recovery will (re)install the version that shipped with the Mac.

The recovery partition is associated with the installed OS - it will (re)install the same OS version that is on that disk.

It is not clear which 'recovery mode' you are referring to.

About the screens you see when your Mac starts up - Apple Support <- See the 'Spinning globe' image, that indicates internet recovery, sometimes internet recovery may fall back to a recovery partition just to confuse matters!

I would trust the installer icons, I don't ever recall Apple making one icon reference another OS in an installer.

musophile01 wrote:

 

I'm also interested, more generally,  about what my rights might be here as a consumer? As I said, Amazon UK seemed utterly convinced they were

selling me a Yosemite system, and I said, specifically gave me this assurance. If Apple gave them the wrong details , might they have some responsibility to put this right - including helping me put the original 'Early 2015' OS back on?

You have the consumer rights that cover all purchases. I believe you get 14 days to return 'no questions asked' on Apple products. That excludes if you have damaged the device.

I suspect that you can return it on the basis that it is unsuitable & was not 'as described' - the OS should be 10.10 if that is what the listing or store told you.

You can look at trading standards and the stores own return policy for the UK rules.

Quite frankly many stores do not know enough about the various OS X versions to sell them accurately. The OS names Apple chooses don't really make any sense unless you follow Apple religiously.  M is before Y, E comes after Y?

I have seen a few complaints that go the other way - buying a 'new Mac' but finding it had an the previous OS X installed when the latest one has been out for a few weeks or months. Those are normally old stock that didn't get updated. Be polite and persistent, you should be able to get a return if desired.

I don't know why I didn't ask this earlier - do you have 10.10 in your App store account purchase history?

If so download that, write it to USB & try installing it…

Create a bootable installer for OS X - Apple Support

If the Mac chokes you know it is too new to install 10.10.

Ask if you need more help with that.