For the most part, IBM and family thankfully included strong documentation on the back of their keyboards in the form of a rear label that usually displays the keyboard's part number along with a date of manufacture. A birth certificate, if you will. Thanks to these, we're able to date most IBM and family keyboards since 1981. However, the style, format and even data points for these rear labels has changed over time, thus this topic will serve as a gallery of known rear labels that can show how they've changed through time and from one OEM to another. Presently, there are 130 keyboard rear labels found/on record.
A rear label on an IBM and family keyboard is a form of per-keyboard documentation that in its most basic form usually displays a part number with a date of manufacture or assembly. It is with these that people can quickly identify and date a keyboard. These rear labels are also known as rear stickers or even birth certificates. Rear labels on IBM keyboards only became consistent in the early 1980s with Model F keyboards; previous types of keyboards such as Model Bs could have widely varied labelling if at all and usually dating such a keyboard relied on a cable tag instead.
During the era IBM and Lexmark manufactured keyboards, there could be two types of rear labels; the outer case (or simply outer or external) label and the internal assembly (inner) label. The outer case rear label is used to display information about the keyboard as a whole. The internal assembly rear label is used to display information regarding just this inner assembly along with the keycaps fitted to it as standard. See for below various examples of rear labels along with their main datapoints highlighted.
Unicomp and TGCS have abandoned using fully-featured internal assembly rear labels and instead rely on outer case rear labels for identification. Lenovo's use of internal assembly rear labels depends on the type of keyboard - their full-travel desktop keyboards generally lack them, but their ThinkPad laptop keyboard assembly derived products may use them.
|Part number||A unique and typically 7-digit code used to describe a specific keyboard, usually by its layout and language. Whilst intra-part number varieties may exist, a given part number is expected to have a set number of features and specs. For example, a P/N 1391401 Model M is always expected to be a PC-compatible 101-key Enhanced Keyboard with a PS/2 connection.|
|FRU number||Also a unique and typically 7-digit code used to describe a specific keyboard but in the context of ordering a replacement for a specific keyboard. Unlike part numbers though, FRUs can specify a replacement that's in fact a different keyboard design but should still have similar functional capabilities (excluding key-switch design).|
|Assembly part number||IBM UK only, also called an internal part number. This one indicates the part number of the internal keyboard assembly and any keycaps on it for keyboards that are not monocoques. It doesn't represent the type of controller, presence of lock-lights or outer case of the whole keyboard. As such, multiple unique outer part numbers can share the same assembly part number. When present on the outer rear label, it's usually printed under the main part number in a smaller font.|
|Model||Before the mid-1990s, IBM and Lexmark rear labels could have a model field that indicates if the keyboard is designated a member of the Model F or Model M keyboard family. From that time onwards, IBM moved to assigning a model number for each keyboard release en masse. Typically, a model number from thereon would include two or three letters to indicate the OEM and 4 numbers to indicate the SKU. Common OEM codes include KB (Chicony), RT (NMB) and SK (Silitek or LITE-ON).|
|Date||Exactly what you expect, the date when the keyboard's manufacturing process was complete. The date format itself can be specific to a given factory's region or OEM convention. In some cases, the date may be a year along with either the week number or month.|
|Shop date||IBM US only, an alternative form of date usually printed on the inside of IBM US keyboards. It's a convention employed by the former IBM Office Products Division (OPD), being a four-digit number that increments with US working days. The convention was believed to have been started around the time IBM Electric Typewriter Division was renamed to OPD, which occured in 1964. Shop date 0001 is thus likely 1st January 1965, the start of the first full year of the division's operation under that then-new name. By the time of Model F and Model M keyboards, shop dates were in the 4000s to 5000s. The convention was ultimately dropped by the early 1990s.|
|Warranty End Date (WED)||IBM RSS/TGCS only, a secondary date found on later IBM POS keyboards and all TGCS POS keyboards that denotes the end of warranty date. WED is typically written with only the month and year.|
P/N 4584656 internal assembly rear label
P/N 5640987 outer case rear label
P/N 6016730 outer case rear label
P/N 6052101 outer case rear label
P/N 4584594 internal assembly rear label
P/N 1503206 outer case rear label
The third value is believed to be the shop date as converting it to a real date gives a reasonable date for this keyboard to be made during
P/N 6052141 outer case rear label
P/N 8323237 outer case rear label
The third value is believed to be the shop date as converting it to a real date gives a value very close to the date code on the keyboard's other rear label
P/N 6090817 internal assembly rear label
P/N 9999399 internal assembly rear label
P/N 6019303 outer case rear label
P/N 1391418 internal assembly rear label
P/N 1390360 internal assembly rear label
P/N 1392611 internal assembly rear label
P/N 2658328 internal assembly rear label
P/N 1392554 internal assembly rear label
P/N 1393388 internal assembly rear label
P/N 4585241 internal assembly rear label
P/N 1394324 outer case rear label
Notable for having the inner keyboard assembly part number printed underneath the main part number (albeit in a smaller font)
P/N 1397003 outer case rear label
P/N 1396924 internal assembly rear label
P/N 0985955 outer case rear label
Has no visible date, thus date must be read from the internal rear label.
P/N 1399300 internal assembly rear label
Lexmark used this minimalist rear label for AR-10 and GS-20 type laptop keyboards
P/N 1379916 internal assembly rear label
P/N 1379593 outer case rear label
This label is identical to the Lexmark UK style found on Model M6-1 keyboards, and it appears to be laid on top of a traditional Lexmark US label.
P/N 1398148 internal assembly rear label
P/N 1395249 outer case rear label
Used on refurbishments of older IBM-made keyboards, seems to be suffering from a Y2K issue with its date value
P/N AC40956 outer case rear label
P/N DD43T56 outer case rear label
P/N UB40T56 outer case rear label
P/N 18U0384 internal assembly rear label
P/N 86H1066 outer case rear label
Maxi Switch removed the "M9" designation for this USB version of the original RS485 M9, but for all intents and purposes, it's still an M9
P/N 42H3979 internal assembly rear label
One of two examples of a "KTC2" M6-1 rear label, made in Mexico. The format and styling seems identical to Lexmark M6-1 rear labels.
P/N 42H3970 internal assembly rear label
One of two examples of a "KTC2" M6-1 rear label, made in Mexico.
P/N 42H3978 internal assembly rear label
One of two examples of a "KTC3" M6-1 rear label, made in Mexico.
P/N 39H4047 internal assembly rear label
One of two examples of a "KTC3" M6-1 rear label, made in Mexico.