|Hitachi||YMW||Y: single digit year; M: month A-M (no I); W: week of month|
|Mitsubishi||YWWRRR||Y: single digit year; WW: week; RRR: running number (official, but does not appear to tie up with 1980s chips)|
|Mitsubishi||YYWWRR||YY: year; WW: week; RR: running number (speculation for 1980s chips)|
Cherry products have a three-character code after the serial number which indicates the year (using a single letter, which wraps around) followed by the week number as two digits.
Modern Dell serial numbers take the form:
CC is the country code of origin (CN for China, KR for Korea etc). PPPPPP is the Dell part number. Y is the final digit of the year; the decade is not recorded, and this digit wraps every ten years. M is the month number in base 16 or 36, and D is the base-36 day number. aaaaa and bbbb are unidentified sequences. The revision number ARR (starting with revision A00) is found on the label affixed to keyboards in recent years (since 2010 or earlier), while on the label affixed to the box the revision number is stated separately. Mice only have a single label affixed to the packaging and these also have the revision number appended to the serial number.
- Single digit: 7 is 2007, 2017 etc; rough knowledge of the product is required to determine the decade to which the year belongs
- Ranges from 1 (January) to C (December)
- Ranges from 1 (1st) to V (31st)
Early label from a 2001 Dell SK-8100, with separate revision number
Label from a Dell KB1421; here 04D gives the 13th of April 2010
Revised label design from a Dell KB216, with the month and year stated directly (6BU → 30th of November 2016)
Many later Tai-Hao keyboards have a serial number in the format brand + YYMM + letter + digit sequence. The brand is typically SOFTCAP (Soft Key) or CLICKER (Clicker). The following label is printed with "SOFTCAP0212H005863", which indicates December 2002:
Tai-Hao F21HQ label
This information was provided by Tai-Hao.