CM - Compact Machines
CC - Computer craft
PC - Pneumatic Craft

The game crashes on startup when running with Computer craft, Pneumatic craft and Compact Machines.

The game will run if CM and CC or CM and PC or CC and PC are together but will not run at all 3 are running at the same time.

Mod Pack crash log

Isolated mods crash log

Compact machines 1.20 works with all the mods but it will crash on CM 1.21

Just add OpenComputers and it will work just fine...
I'm not kidding here

Will all computer craft programs work 100% with opencomputers and what is the difference between the two?

He's saying your 3 + OpenComputers. Just don't use OC

Add, but ignore

That I can't guarantee but it will certainly not crash at startup, worth testing

I did add at the bottom that the crash only occurs on the latest version (1.21) but it works fine on 1.20

I'll diff them, see what was changed.

Also, about the programs, no, they would not be 100% compatible, however, if you wanted to use OC instead of CC, it shouldn't be that big of an adaptation.

Do the two mods work along side each other?

Edit: They do

The problem seems to be the following:

• Mods are loaded alphabetically unless otherwise defined in their Mod annotation.
• PneumaticCraft uses ComputerCraft if it is available, but does not specify that it needs to load after it.
• CompactMachines wants to be loaded after PneumaticCraft if it is available, which seems to move PneumaticCraft to the front of the list with ComputerCraft still being behind CompactMachines, i.e. when all three Mods are active they load in this order:
  1. PneumaticCraft
  2. CompactMachines
  3. ComputerCraft
• This throws PneumaticCraft of the rails, because it tries to use ComputerCraft without it being loaded yet.

Solution: add after:ComputerCraft to the dependencies of PneumaticCraft.
I'll open a pull request on PneumaticCraft.

Currently working on a 1.10.2 version, the 1.7.10 version is not being maintained anymore, sorry.
Closing all issues not relevant for the new version.