Help identifying National Semiconductor I.C.

Thread Starter


Joined Jun 26, 2020
Hi everyone.

This ought to be easy, but I've been searching through old IC handbooks for days now without success.

I think the date code is the /P211 part. I think it's old because the logo is one of National's older ones, plus the I.C. belonged to my dad. Most of his electronics buying stopped in the 1970's.

Anyone know what a National 1789 I.C. is?

Thanks for your help,




Joined Jun 26, 2012
Welcome to AAC!
1789 is the date code - 17th week of 1989. It’s in the right place for that.
P211 is probably an in-house number- a standard chip re-labelled for a specific customer and not readily identifiable. That’s my guess anyway.

Thread Starter


Joined Jun 26, 2020
Thanks JohnInTX for the reply.

You may be right about the house numbering. I still think the part number is the 1789, though. I've found several other more recognizable devices from National Semi that have the part number on the second line. The top line often has a symbol like a colon, plus, slash, or other followed by a letter and 3 or 4 digits. If it's a date, it is well coded!

Here are some of those more recognizable devices from the "old logo" era.

I'll keep looking at old data books. I've no idea why I'm obsessing over it, though.



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