Ever wondered what year that old chip you have laying around was? Are you just simply curious? Here's how to read the date codes on most common ICs/chips.
Everything I have here is based of the (surprisingly little) info I found on the web. If you know something I said wrong, or something to add, by all means, please tell me!
Step 1: Find the Date Code
"Uh..." (Squints at chip) "Lemme see..."
First you need to locate the date code. If it's there, (Some chips just don't seem to have one), it's likely it's a 4 digit code. Usually the 4 digits are by themselves. In the picture, the 4 digits circled in green is the date code.
Step 2: Read Date Code:
So you've found the date code! Hopefully you didn't need a magnifying glass! (Some chips are really hard to read off of...)
The date code usually is in either of two formats: YYWW or WWYY, where WW stands for the week number of the year (Not the month, seems strange, doesn't it?), and where YY stands for the last two digits of the year. For example, in the picture, the date code reads 8332, meaning it was made in the year 1983, in the 32nd week.
As verence helpfully pointed out in the comments, most datasheets will
have info on how to read the date code, as long as you can find a datasheet. ;)
There are a few reasons that chip makers use the week format rather than months, but the main reason is because it narrows the date down even more than a month, to the exact week. That can be useful for tracking batches of bad chips that need to be returned.
Step 3: Finished!
Hopefully this was some help to you!
Unfortunately, however, a lot of chips, (At least many of the ones I have) seem to either not have date codes, or be in a different format I've not found yet. If you know of more formats, please tell me in the comments, so I can add them to this instructable.