CPU Affinity Mask Calculator

on GitHub

How to Set the CPU Affinity of a Windows Process

The best way is to use Process Lasso’s rules to create sticky CPU affinities that persist. 

CPU Affinity Rules
Process Lasso CPU Affinity Rules

Alternatively, if you want to start a program at a specific CPU affinity once, you can use the Windows terminal Start command.

start /affinity 0x0000000000055500 notepad.exe 

When run from the Start Menu, you would need to include the command shell (cmd.exe), for example:

c:\windows\system32\cmd.exe /C start /affinity 0x0000000000055500 notepad.exe