Franc Zabkar wrote:
I can see the patterns for Sharp, NEC, Toshiba, Sanyo, and Hitachi,
and I can guess at the patterns for Rohm and Mitsubishi, but the rest
are a puzzle. I see that in your notes you have suggested that the JRC
year digits may be reversed, but this doesn't tally with the 78M09A
part. I see what you are suggesting for the Matsu****a codes, but then
how do you account for the MN1451BVK parts? I tried Geoffrey's
suggestion regarding Hirohito's coronation year (1926?), but I
couldn't make it fit the data.

Hirohito was crowned Dec 25, 1926, but the new one was crowned 7 January 1989.

Some parts made in early 1988 were date coded with a year of 62 (they
start at year 1 I think), and after 25 December 1988 were dated year 63.
Since it is considered unforgivably rude to prepare for the death of the
Emperor, things made in early 1989 were still date coded 63 for a short
time. It's also rude to continue to use the old dating system, so some
companies stopped production until they could change the dates.

Very likley then things produced went from a year of (6)3 to 1.

Geoff



--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM