HELP ON NEC Z80 DATE CODE

[YG]

Hello can you please tell me which year was manufactured a NEC D780C-1 ( = Z80A): it says D780C-1 and then it has NEC JAPAN P15075-120 and then on bottom part of mold they have letters like C4 in one cirlce and then a 5 in other circle.

Thank you
Kind regards
Y&G

[hugo929]

I suspect 150 is the datecode, then it might be 1981,1991 or 2001 year

[Borris70]

maybe the "P" is an "8" and then it is mfd 8150

my D780C-1 is like this one

http://www.chipdb.org/img-nec-d780c-1-2225.htm