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VirtualAcorn Technical support:
Running a 32bit VirtualRPC on Mac OS X 10.15 or later

This article contains a number of suggestions for different ways you can run VirtualRPC on Mac OS X 10.15 (Catalina) or later. This article is provided for information purposes only. We will not be able to offer any technical support related to the implementation of any of these methods. Please remember to take a complete backup of the VirtualAcorn folder in Applications first, we recommend you copy this backup to a removable storage device for safety.

This article contains links to third party websites, we don't receive any payment for clicks on the links or any advertising revenue from the owners of the websites. We've provided these links because the content might be useful.


Currently VirtualRPC is a 32 bit application. There's no technical problem with running 32 bit code on 64 bit hardware with a 64 bit OS, both Windows and Mac OS have been doing it for years. However with the launch of Mac OS X 10.15 (Catalina) Apple have disabled support for 32 bit applications and that means that VirtualRPC won't run on Catalina. If there is enough demand we will look at developing and releasing a 64 bit VirtualRPC but are you stuck on Mac OS 10.14 (Mojave) until that happens? No.

If you want to run Catalina you don't have to overwrite your copy of Mojave and give up VirtualRPC. In this article we explain a number of methods that could be used to run VirtualRPC and also use Catalina.

Copy or Partition your hard disc

These methods work by keeping or copying your Mojave install and then installing Catalina so that the entire Mohave installation is preserved. You don't need to purchase or download any applications if you create a new partition for Catalina as all the tools are built into Mac OS X. The disadvantage with these methods are that you need to shutdown and reboot to switch from 64 bit to 32 bit.

1. Boot from an External drive

Provided you haven't already upgraded your Mac to Catalina then this is probably the easiest solution. You will need an external storage device, typically a hard disc, which can be used to duplicate the contents of the drive in the Mac. It's best to start with a new drive or at least one which doesn't have any files stored on it. The drive needs to be large enough to store a copy of your internal storage device. So if your Mac has 1GB internal drive you will need at least a 1GB external drive.

You then need to backup your hard disc using either Super Duper or Carbon Copy Cloner. At the time of writing Carbon Copy Cloner is available on a 30 day trial which is more than enough time to set up Mojave on an external drive. Make sure that the external drive is set as bootable when you copy Mohave.

When you want to use RISC OS all you have to is shutdown the Mac and then boot from the external drive. Once you've checked that the external drive is booting correctly and everything works you can then upgrade your Mac to Catalina, but do make sure you are booting from the internal storage device first.

2. Using Mac OS partition tools - FREE

If you are familiar with the handling of discs in Mac OS X you can do this with these simplified 8 steps:

  • Open Finder and click Go on the top left of your desktop.
  • Click on Utilities and then click on Disk Utility.
  • Select your Mac's Boot hard disc and then click on Partition at the top.
  • Click on the plus button to create a new partition.
  • Type in a name then choose the APFS File System.
  • Choose a size for the new partition in GB
  • Click Apply to create the new partition.
  • When you install Catalina make sure you choose the new partition as the installation location.

Once completed switching between your Mojave and Catalina is easy. Click on the Apple logo at the upper left of the desktop, click on System Preferences and then click on Startup Disk. Click the lock at the lower left corner to make changes and then type in your system password. Finally, select the correct partition and restart your Mac.

If you would like more details on this method then this article from Apple should help:

3. Bootcamp - FREE

You could certainly use Bootcamp to install two different versions of Mac OS X, but it's just adding another layer of complexity and gives the same working result as partitioning your hard disc or booting from an external drive. So we would recommend that you stick with the partitioning built into Mac OS X.

Using Virtual machines

Partitioning is the easiest option to setup but has the big disadvantage that you need to shutdown and reboot to change which version of Mac OS X you are using. If you need to constantly flick backwards and forwards it's not a sensible solution.

The following three methods allow you to run both Mojave and Catalina at the same time so you can switch between 32 bit and 64 bit apps on the fly. Many users are familiar with Parallels as it's often used to run Windows and Windows applications in a virtual machine. Of course it can do more than that, instead of creating a virtual Windows machine why not create a virtual Mac running Mojave. Then the VirtualRPC (and any other 32 bit applications) can be installed inside the virtual machine. So your real Mac runs Catalina but you can easily switch from 32 bit and 64 bit with a couple of mouse clicks.

The rest of this article gives you some ways to achieve this along with links to detailed instructions.

4. Parallels - Monthly Subscription

This method is very simple to explain. You create a new virtual machine in Parallels and then install Mojave into this virtual machine. Then you copy/move your VirtualRPC into the virtual machine. You can then either run VirtualRPC on Mojave inside the Parallels window or you can use Parallels Coherence mode to run VirtualRPC in Catalina's desktop.

Supposing you don't own a copy of Parallels Desktop? You could try the Parallels Desktop Lite Demo which will run for 14 days before asking for a subscription fee. If you do find that Parallels suits you it's often cheaper to buy the full Parallels Desktop yearly subscription rather than pay a monthly subscription for the 'Lite' version.

This article from PcMag explains the entire process:

Just remember that as Parallels is now sold as a subscription service so there is an ongoing cost associated with this method

5. VirtualBox - FREE

You don't have to use Parallels to set up a virtual machine, instead you can use VmWare's VirtualBox which is free of charge. It has the advantage that it's free but the installation method for the hosted OS (In this case Mojave) is more complex than Parallels and there's no hand holding installation tools. In addition the integration into the Mac desktop is not as good as Parallels, but VirtualBox is free. The following article explains the set up process:

6. VMWare Fusion - Single cost

This is a little bit left field. VMware Fusion often costs the same as Parallels to buy (around $80 - price correct October 2019) but you are purchasing the product outright and so there's no on going subscription cost to worry about. The latest version of VMWare Fusion doesn't quite have the same level of integration as Parallels but it's very close. However it does have one big advantage, the licence allows home users to install it on several computers at the same time. If you have a Macbook and an iMac and need to run VirtualRPC (or any other 32 bit applications) on both then VMWare Fusion is well worth considering. Setup instructions for running Mojave can be found here:

Other methods that might work

For completeness sake we do need to mention that there are some other methods you might be tempted to try but which may not work.


(Wine Is Not an Emulator) is a set of compatibility libraries that allow applications designed for Windows to run on other operating systems. It's highly unlikely to be able to run a Windows VirtualRPC without a lot of technical configuration. Even if you can get VirtualRPC to boot there are so many problems to overcome that anyone who isn't highly skilled will never succeed. We've never had any successful reports from customers trying to use WINE despite dozens of people trying. Keyboard and mouse input tend to be a problem especially control of the RISC OS mouse pointer. If you have a spare Windows version of VirtualRPC and the spare time to try WINE you could try it, but a better suggestion might be Crossover.

8. Crossover

We've got no experience of Crossover but we are including it as it might be a workable option for some users. If someone wants to try it please do let us know how you get on. Crossover is a specialised build of WINE that comes with technical support and a host of GUI improvements and a great many ease of use improvements. You will still need a Windows copy of VirtualRPC but there is a demo version of Crossover so it would make more sense to start experimenting here than with WINE. Details on Crossover can be found here:


Finding any reliable (i.e. non biased) performance tests of virtualised environments has been difficult because in many ways such tests are artificial and different systems have different strengths. We can't make a recommendation to say which is 'better' because all the solutions might be better on one test and worse in others. Our advice is to start with a no cost option, if you already have Parallels try using that. If not then start with VirtualBox unless you already have a VMWare Fusion licence.

Hopefully this article shows that installing Catalina doesn't mean the end for VirtualRPC.

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Last Edit Date 01/04/21