Answer:
The short answer is, for full-mission flight simulators, specifically by NASA, are built with actual hardware and supported by simulation software. These software take into account every possible scenarios that could be adjusted based on the training. As for the hardware, they receive signals from the software on what they should do.
Explanation:
Some technologies involved are (which are also part of the FAA's requirements):
- 6 Degrees of Freedom for motion
- Visual systems
- Realistic acoustics
- Visual effects
This also involves a lot of robotics.
On the topic of motion:
One big and important feature is how motion is simulated - which takes a combined effort of both software and hardware to actually simulate how external forces can also affect the body.
It also takes into account the vibration that is experienced during launch.
The 6 degrees of freedom for motion includes:
- Up and down
- Left and right - sliding motion
- Back and forward
- Yaw - turning motion
- Pitch - look up and down
- Roll
For flight simulators, there are several levels and requirements being used in the aviation training industry. But one thing that you need to know is that the hardware and software mostly take into account motion.
On the topic of visual systems:
The pilots or crew should have a visual representation of what the outside world looks like with at least 150 degrees of view.
Realistic acoustics:
During simulations, actual sounds should also be present based on the real-life sounds produced during flight.
Visual effects:
If the pilot pivots to the right, or is about to breach the exosphere, the system's display should also take that into account and show it to the crew. This also includes visual effects for specific motions being done.
And as a bonus:
Just until recently, everything was analog (meaning, with dials, buttons, and levers) for the actual aircraft simulation that the pilots/astronauts are using. Update are now being made in NASA and SpaceX along with other rocket and spacecraft companies to move from analog to digital (with touch screens).
While this is an abridged version, it should help you to understand the complexities of a flight simulator.