You should be able to work it out from the info on the following link
http://roland-jupiter.org/viewtopic.php ... ght=serial
And from another thread, dougt is quoted as saying
"The first 2 digits tell you the month and year the synth was made starting at "00" for Nov. 1980. So "01xxxx" would be Dec. 1980, "02xxxx" = Jan. 1981, etc..."
Hope that helps
And on that note....Happy New Year to all forum members