Your blog inspired me to update a long-forgotten page on EDN, Home-Made Digital Clock Keeps on Ticking. It's about a digital clock I built in college that's based on a National Semi MM5316 clock chip. You can download a PDF of the data sheet there.
Try your search and see if you have the MM5316. If you do, your scanned version is probably of better quality than mine. That scan was from a fuzzy photocopy made long ago.
I will do it tonight- I don't have the Adobe PDF reader here. Although I must say it doesn't look promising- I don't seem to have a National MOS data book- in amongst the multitude of others. Colour me disappointed.