Casio calculator Chip date codes

From: dave
Email: davegostelow@yahoo.com


Hi, Is there anyone out there who knows if there is a date code on Casio chips and if there is how to decode it. I have a few 1970's Casios and they have these chips in them: FX3600P HD43147 0F 11 FX39 HD38111A 0B 33 FX19 HD36130 6G 33 FX20 uPD978C H56046 FX29 HD36130 7J 23 FX102 HD36130 6E 31 FX502 HD43108A 0A 45 HD43109 9L 45 FX31 HD38111A 9F 33 702P HD34190A03 1K 33 HD43190A02 1L 13 HD43191A03 1L 33 HD43191A02 1L 43 It looks like the Hitachi chips might have a date code where 6G could mean 1976 july and 1L is 1981 december. Does anyone know if this is correct? Also, what are the last 2 numbers? There is one problem with my date code theory, I believe the 3600P came out in late 1981 and the date code on the chip indicates mid 1980. I don't believe the chips could be over a year ealier than the calculator.