# How to support 2 different PTB versions on same Mac?

**URL:** <https://psychtoolbox.discourse.group/t/how-to-support-2-different-ptb-versions-on-same-mac/361>\
**Category:** Uncategorized\
**Created:** [January 22, 2013, 5:33pm UTC](https://psychtoolbox.discourse.group/t/how-to-support-2-different-ptb-versions-on-same-mac/361 "2013-01-22T17:33:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dxjonespix](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@dxjonespix](https://psychtoolbox.discourse.group/u/dxjonespix)\
**Post date:** [January 22, 2013, 5:33pm UTC](https://psychtoolbox.discourse.group/t/how-to-support-2-different-ptb-versions-on-same-mac/361/1 "2013-01-22T17:33:40Z")

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Hi,  
  
I need to maintain support for PTB 3.0.9 (svn 2178) and MATLAB\_R2010a (32-bit), because I need to support code for experiments running in other labs with this setup.  
  
But at the same time, I need to upgrade to the latest PTB (latest stable release) and MATLAB\_R2012b (64-bit).  
  
I am using an iMac, Mac OSX 10.6.8, and I can have 2 different versions of Matlab with no problems.  
  
But I don't know how to set up PTB because, by default, it lives in /Applications/Psychtoolbox (with no version numbers).  
Consequently, upgrading PTB will clobber my previous version 3.0.9  
  
I am sure other people have solved this problem before.  
  
Any help would be appreciated.  
  
-- David Jones

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**Author:** ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner)\
**Post date:** [January 22, 2013, 5:50pm UTC](https://psychtoolbox.discourse.group/t/how-to-support-2-different-ptb-versions-on-same-mac/361/2 "2013-01-22T17:50:54Z")

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--- In [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com), "dxjonespix" wrote:  

> \>  
> \> Hi,  
> \>   
> \> I need to maintain support for PTB 3.0.9 (svn 2178) and MATLAB\_R2010a (32-bit), because I need to support code for experiments running in other labs with this setup.  
> \>   
> \> But at the same time, I need to upgrade to the latest PTB (latest stable release) and MATLAB\_R2012b (64-bit).  
> \>   
> \> I am using an iMac, Mac OSX 10.6.8, and I can have 2 different versions of Matlab with no problems.  
> \>   
> \> But I don't know how to set up PTB because, by default, it lives in /Applications/Psychtoolbox (with no version numbers).  
> \> Consequently, upgrading PTB will clobber my previous version 3.0.9  
> \>

You can define the installation folder during DownloadPsychtoolbox() - there's no reason whatsoever it needs to go to /Applications/, it is just a reasonable default.  
  
Then you need to have two separate Matlab M-File path definition files for your different Matlab's - the Matlab manual explains how to define these if it doesn't happen already automatically for separate Matlab installations.  
  
-mario  
  

> \> I am sure other people have solved this problem before.  
> \>   
> \> Any help would be appreciated.  
> \>   
> \> -- David Jones  
> \>