C4004 with date code (?) of F3864

[westing]

I've looked around the web for information on how to interpret the code, but haven't found anything. There is nothing on the underside of the chip.

Could anyone tell me what the "F3864" means - such as build date, and location?

I pulled this out of the trash on a "lab cleanup day" at my first job, more than 30 years ago. I also got a P4002-1 F3273. They were in some kind of trainer board - wish I took the whole thing!