Old chip date code - anyone understand it?

[TerraHertz]

Sorting out some very old ICs, I came across this date code series.
These are all MC899P, MRTL (Medium power Resistor Transistor Logic, MC700/800 series) from the late 1960s through 70s. It's a "dual buffer."

In the photo the left hand pair are the earliest - they have the 4 bumps on the package underside, that rapidly went out of style. The next pair's date code is 7204 ie 4th week of 1972. The right hand pair are 7725, 25th week of 1977.

But what does "905" mean? Is it a date code or something else?

Oh, and those were the days when ICs might be supplied in little styrofoam boxes. Before static electricity was invented.

[elecman14]

Guessing the 5th week of a year ending in 9. If you really wanted to get to the bottom of it you may be able to find the date code format in a data book. I would start looking at 1969 since the 70's parts seem to have the 4 digit format.

[amyk]

Single-digit years are 196x.

[TerraHertz]

Single-digit years are 196x.

Ah ha. I guess that makes sense as a general rule, since there were no ICs before the 1960s.
So really the rule is 'three digit date codes have just the first digit for the year.'


I wonder if any of the people doing IC package dissection to photograph the die, have done very old
logic like the early RTL & DTL chips.

It turns out that among a recent 'old parts windfall' I now have a good range of those.

[magic]

These biologists tore down a few very old chips from their lab's spare parts drawer, apparently as an excuse to play with FNA and their microscope toys

https://resnicklab.wordpress.com/2013/05/

There is some digital rubbish in there, I haven't even looked at it

[floobydust]

I have National Semiconductor LM3914 I am sending to Noopy, date code 007.
Pretty sure that is 1980, as the part was not out in 1960 or 1970. The old data books could find no info explaining the date codes.
As I recall, three digit codes the "decade" was left out and assumed to be something people could figure out.