What is it?
A tiny wrapper program that will start itself, set its CPU affinity, then spawn another program specified on the command line, which will inherit this affinity.
Why would I want that?
If you don't have an NT-based system (Windows NT/2000/XP), or you have such a system but only have one CPU in your machine, you don't.
If you have a multi-CPU NT-based system, setaffin can make badly-behaved programs play nice by only seeing one CPU in your box. Mostly, so you can run various Direct3D games that don't 'play nice' with multiple CPU's, although I'm sure there's some other applications for this little widget that I've never thought of.
How much does it cost?
Not a thing. setaffin is Free/Open-Source software, released under the Gnu Public License. Which doesn't stop me from charging for it, but that would be silly for this little blob of 63 lines of C code. It's free to take and use, modify, and so forth, but if you aren't familiar with the GPL, please read the file "COPYING" inside the distribution zipfile.
Great! That's me, 2-CPU Win2K box with crashing Deus Ex! Where can I get it?
From its github page, of course!
Is this horribly buggy pre-alpha software?
Yes and no. It works perfectly for me. It might set your whole house on fire. I'm hoping to get feedback to make it better, so you tell me -- is it horribly buggy pre-alpha software?
This software has changed my life! How can I thank you?
Just write me and tell me that. If you are REALLY interested in doing something nice for me in return, write me and tell me that, too. I'll likely have you make donations to the Electronic Frontier Foundation or the Juvenile Diabetes Foundation. In fact, do that anyway, just on general principle.