IBM "Shop Date"

[phosphorglow]

This has confused me for a while. And apparently many others as well. Some people say there's a week of production code in there, or it's a variation of a Julian date. So I started a spreadsheet of Shop Dates.

And then I just stumbled over this photo of an internal label on a Model F where a worker wrote the date next to the "Shop Date"

2014-03-18 22.21.49 by Sean Forrester, on Flickr

5/29/84 = 4829

So I started adding and subtracting in my spreadsheet and had a theory: what if it's based on working production days?

There were 252 working days in 1984, with holidays accounted for.

So, let's jump to 1989. An example Model M with an internal shop date of 6096 and a case date of 4/03/89. The correlation between the two is approximate, because the sub-assemblies weren't manufactured the same day the label was slapped on the case.

So! 6096-4829=1267

1,267 working production days between them.

How many working days between 1984 and 1989?
'84 - 252
'85 - 252
'86 - 251
'87 - 251
'88 - 251
1,257

10 days difference can't be coincidental.

So!

Let's go back in time, where does shop date 0001 bring us? Well, I didn't get exact with working days through the years and used an average of 250, bringing us back to 1964.

"In 1957, the Electric Typewriter division also completed transfer of its manufacturing and engineering operations to a new plant at Lexington, Kentucky.

To indicate more accurately the scope of the product line, the Electric Typewriter Division changed its name to Office Products Division in August, 1964"

https://www-03.ibm.com/ibm/history/exhibits/modelb/modelb_office.html

Adding a little more...:

Late summer 1990 marked the end of Lexington's ties to IBM's manufacturing operations. Lexmark took over IBM's operations in Lexington on 21 March 1991.

Referenced from here.

I have a lot of pictures to plug into my spreadsheet, but I can say that the early style internal label with the shop date appeared on a board from 1/23/90, but not on a board from 6/11/90, which falls in line with the transition period mentioned above.

It's the best theory I can come up with, anyways.

[SpAmRaY]

This is awesome. Thank you for sharing!!

[CPTBadAss]

This post has the appropriate amount of math and science. I'm way into it. <3

[xtrafrood]

Hmmm, more info on this subject would be great 

[E TwentyNine]

Interesting.  I expect some data in this thread from the masses to confirm this with our own labels.

More importantly: Can finally narrow down dates on these F's that have no obvious date info.

So.... one of my F's has an plate date of 5598, which should put it around June 87?

[phosphorglow]

MOAR DATA!

@E29:

5598 I estimate to be somewhere in the last two weeks of April '87 (...or about 2 years and 9.6 months since 6/1/84). It's birthday is coming up. 

Here's a fun spreadsheet that's editable by anyone, because that seems like a good idea. Add in a shop date and see if it falls close to your case label date.
https://docs.google.com/spreadsheets/d/1CmlG2k9UM-t539G5COv7NBe2pNsQ_W7ktKiEXs1TP3o/edit?pref=2&pli=1#gid=0

My math is a little silly, but I think it's the best I can get based off of a single date and not knowing the exact days IBM counted as production days. But it's pretty freakin' close.

[E TwentyNine]

MOAR DATA!

@E29:

5598 I estimate to be somewhere in the last two weeks of April '87 (...or about 2 years and 9.6 months since 6/1/84). It's birthday is coming up. 

Oddly enough it has "3/3" written on it.   Discounted it because I thought June, and while not quite April, not sure if it means March 3rd or if it's some quality/test check.

[phosphorglow]

I'm pretty certain you're right about that being a quality/test check. A lot of F's seem to have the same thing. Two handwritten digits, but no double digits on either of them.

[pr0ximity]

Very interesting. I have a couple of labels to add when I'm home. Would be very interested to figure iut what it all means.

[phosphorglow]

Indeed! Feed the data machine! I'd really be curious about UK manufactured Model F's. I bet their shop dates are different.

@E29:
I forgot how to count months on yours. ;P
Somewhere towards the end of March, not April. But I still believe those two handwritten digits are related to testing/QC.

[ch_123]

Seriously impressive work phosphorglow!

[romevi]

Slight necro.

My SSK came without a label on the back of the case, so I'm trying to see if I still can figure out the part number and manufacturing date. When I open it up, the shop date reads 528584.

Does that mean it was made in 85?

[Moistgun]

Slight necro.

My SSK came without a label on the back of the case, so I'm trying to see if I still can figure out the part number and manufacturing date. When I open it up, the shop date reads 528584.

Does that mean it was made in 85?

I think your specific shop date is 5722 

Sometime mid to late 1987?

[chyros]

Slight necro.

My SSK came without a label on the back of the case, so I'm trying to see if I still can figure out the part number and manufacturing date. When I open it up, the shop date reads 528584.

Does that mean it was made in 85?

Pretty sure SSKs weren't made in 1985 yet.

[romevi]

Slight necro.

My SSK came without a label on the back of the case, so I'm trying to see if I still can figure out the part number and manufacturing date. When I open it up, the shop date reads 528584.

Does that mean it was made in 85?

Pretty sure SSKs weren't made in 1985 yet.

Yeah, I Googled a bit more after I posted that. I think mine might be 1987.