You can emulate an NI-Desktop Real Time(RT) System in a virtual machine using VirtualBox from Oracle. This helps in great ways…
You don’t need a separate PC to check your logic in real NI-RT without even an extra physical PC in your side. Testing in customer site would not require additional logistic of other PC.You don’t need cRIO or PXI to start learning/coding your RT application
Check my virtual machine running NI-RT below with 1-core processor, 512MB RAM and 2GB HDD which I created within 2 hours from scratch.
I want to credit and thank the user "D4N!3L3" in NI forum who was the one successfully did this virtualization of NI-RT and put it up in this idea exchange. The instructions given by him/her is very crisp and short where I lost searching for unclear items. Hence, I’m adding detailed instructions here
Here are the quick steps to do this
Download the VirutlaBox and install it in your windows machine.
Create the Desktop RT USB drive in your pen-drive using NI-MAX
Create a virtual machine with one of NI-RT supported Ethernet cards from this link for the virtual machine. I chose Intel 82545EM. And set it to Host-only adapter.
Add a SATA controller for the virtual machine. This will be used as primary disk. And also add IDE controller if it’s not there and add the existing drive usb.vmdk. This usb.vmdh file has to be created following the procedure in this link. The primary reason for creating this file is to use your Desktop RT USB pen-drive as bootable drive.
Now start your virtual machine and you will find that your Desktop RT boots from pen drive. You will get a menu of options
Select Format Menu –> Format Hard disk Option –> Erase All Partitions –> Reliance file table. Then type "yes" to confirm the format with NI-RT
Once it’s done, go back to main menu and select shutdown option in main menu to shutdown your virtual machine ( I did hard shutdown as I was getting some error if any command from RT tries to restart the machine). Then go the virtual machine settings and remove the IDE storage controller which you added in the earlier step.
Now start your virtual machine, it will load with the RT from your virtual drive. It will detect the network card and initialize the NI-RT. Now you can find the remote systems in NI-MAX listing your remote desktop. 
But there would be no software to run in RT. You have to install the required software using NI-MAX.
But there would be no software to run in RT. You have to install the required software using NI-MAX.That’s it…! You have a RT-Desktop in virtual machine without need for an extra physical PC.
Sometimes you may not find the software section under your remote system in NI-MAX. In such case, change the RT’s DHCP IP to static IP, you can get the software list in NI-MAX.
For this you have use the same subnet used for VirtualBox which you can find under its network details.
Ajay is a professional developer and architect of NI-LabVIEW applications with extreme interest in getting the hardware connected to LabVIEW and automating the stuff. Recently he is also putting his hands in NI-TestStand to get very dirty on it. He is also a good mentor for the various interns in his career. He is ready to help the people in techie roles.