emmafrost1 wrote: 18 May 2023, 13:39
Yes, the letter at the beginning of an IBM Model M serial number does mean something special. The letter indicates the plant where the keyboard was manufactured.
A: Lexington, Kentucky
B: Chicopee, Massachusetts
C: Austin, Texas
D: South Carolina
E: Japan
F: Mexico
G: Taiwan
H: China
So, your keyboard with the serial number F4185 was manufactured in Mexico.
IBM changed the format of their serial numbers in the early 1990s, and the letter at the beginning of the serial number was no longer used to indicate the plant of manufacture.
I would ask for a source for this but it seems this might be AI-generated...
But for the sake of the OP not being confused, regardless of origin, IMO the above doesn't seem to match up with current understanding of how IBM reported plant codes on keyboards. Being the nerd and the "shark with a massive database" that I am, I have records that seem to break the statements.
There are
"F"-id Model Fs produced in 1984, which would be two years before the IBM Mexico Guadalajara plant would start making keyboards (I don't recall any other plant making keyboards before that).
"H" has been spotted on an F122 and I have not heard of any IBM Model F or M being made in China, at least not until the 2000s when
IBM used XSZ as the OEM for IBM Models M7 through M11 and those aren't even buckling spring.
Some keyboards also have a number as the first digit instead.
Tangent time
To set the record on IBM plant/factory reporting, IMO, it's patchy at best. The obvious PLT "plant" numbers have been shared between keyboards obviously made in the US and the UK. When asked, IBM and Unicomp didn't recall what they meant and iirc ClickyKeyboards had a few theories that it might mean something completely different. The only plant code that makes sense to me is the
two-digit integers Ardent Tool has listed since I can at least find them on keyboards. Here are some examples:
(If you're wondering why I went into detail, I'm working on an article on IBM plant codes and potential misconceptions with them hence why this is in my mind right now. Stay tuned, my friends!)
The return to OP's question
The short answer is that I don't think we know for sure what that letter means, but IMO it's likely just there to add another dimension to the ID/serial. 36 (26 letters plus 0 to 9). Without that digit, the possible ID/serial space would be very small indeed. IBM U.S. would have to made just 9,999 keyboards before requiring a change of ID/serial nomenclature. That said, there are other things strange about the serial space since as seen by this
week 33 and
34 example of the same keyboard, the earlier keyboard has a higher number than the later! As I think I've said before, IBM just doesn't make sense and trying to make sense of it would be a full-time job.
, an early production Model F AT. I was wondering what this particular ID meant. I didn't believe it to be the 55th unit produced.
