What are the markings on the bottom of 486's for?

[Compgeke]

Ok, I've got 7 486 processors and one Overdrive. They all have one or 2 letters on the bottom and 2 or 3 numbers, except one but it's not an Intel designed one (bottom says Jaton but it's a Socket 3 Intel 486).

The 1st says "GS" and "528"
The 2nd says "FM" and "444"
The 3rd says "FM" and "445"
The 4th says "CK" and "328"
The 5th says "ES" and "409"
The 6th says "GB" and "28"
and the 7th says "U" and "20".

Thanks!

[Neon_WA]

the letters are some internal assembly system Intel used

the numbers are some sort of "test" date a generally closely mates the FPO on the top of the processor

the 3 digit is YWW >> Year Week so 528 is 1995 week 28
the 2 digit is WW >> so 28 is week 28
You will need to the long code on the die cap to work out the year
the 2nd character is year.. 3rd & 4th is week

so if long code is 25069944AC (1995 week 06) so "test" code is 1995 week 28
if long code 1451035654AA (1994 week 51) the test code also has to be 1995 week 28

[Compgeke]

I managed to figure out the dates, thanks. The oldest is "C1230002" which, if I'm correct, Week 23 of 1991, however that's the U20 one also so the 20 and the 23 don't match up.

[susl45]

[Neon_WA]