Integrated circuits do not get any simpler than this. This is an HCF4007U made by ST with a week 27 1993 date code
According to the datasheet it can be, depending on the pin connections, either 3 inverters, a 3 input NOR or a 3 input NAND gate.
(click on image for high resolution version)
And the pin-out
There is one mystery to me. The part is definitely CMOS as the datasheet specifies it, so they must be polysilicon gate MOSFETs. Yet if you look at this high magnification image of a transistor edge, I cannot see the polysilicon??
Thanks to Jeremy for providing the part.