question about proximity of hp41c/cv serial numbers

[aarong]

Hello,

Just curious. This never crossed my mind until this week, but my two "personal" boxed 41C and CV share this proximity:

One has SN 2427S44214
One has SN 2427S43309

I was just curious as to thoughts about how close in time these (at least the backs) were produced. I know they are the same week. But how far apart in time are 905 units? Days, hours, minutes?

thank you for your musings,
aaron

[rprosperi]

Doing simple math, and assuming:

-45000 units made that week (likely more)
-8-hour day
-5 day week

45000 / 5 / 8 => 1125 / hour

So, less than an hour apart.

The assumptions are likely low, running > 8 hours per day and possibly more than 5 days / week, so you can safely conclude between 30-60 minutes.

But it has been reported that the "week" component of the SN, at least in some places, were not truly a week long, but rather reflect what week that batch began, so it's impossible to know for sure. In any case, getting siblings that close together, from almost certainly very different paths through life, is unexpected.

[Martin Hepperle]

Are there some published production numbers of the HP 41 and maybe its variants?
Similarly for the 71 and other calculators?

Assuming 1 Million (is this correct?) produced at a rate of 45000 per week = 22 weeks.
At that rate, the whole HP 41 production would have taken less than one year.

The assumed numbers peer week seems to be a bit on the high side.

[Didier Lachieze]

(11-10-2023 03:13 PM)Martin Hepperle Wrote:  Assuming 1 Million (is this correct?) produced at a rate of 45000 per week = 22 weeks.
At that rate, the whole HP 41 production would have taken less than one year.

The assumed numbers peer week seems to be a bit on the high side.

Since the beginning of 1975 when HP moved to effective production Month then production Week in the serial number, the serial number range is common for all models, which means that ~45000 hp calculators (or may be hp products overall?) have been produced in Singapore this week, it doesn't mean that it was only HP 41 units.

[brouhaha]

(11-10-2023 12:57 PM)rprosperi Wrote:  But it has been reported that the "week" component of the SN, at least in some places, were not truly a week long, but rather reflect what week that batch began, so it's impossible to know for sure.

It may be that caclulator production weeks weren't exactly tied to the calendar week, but most of the confusion I've seen online about HP serial numbers came from calculators having a different serial number scheme than all other HP products at the time, such as test instruments.

The traditional HP serial numbers did have the YYWWLnnnnn format, but the YYWW was the week the _series_ began, and if there was a revision to the product, i.e. for design or production changes, they would start a new series. That way the service manual could include backdating for earlier series, and just say "If the instrument serial number starts with 7815..." Thus for non-calculator products, the same YYWW series could be used for YEARS.

Calculator production rates were too high for that scheme, thus for calculators and accessories the YYWW became the actual production week, or close to it.

I assume that as HP introduced high-volume consumer products other than calculators (e.g., printers, ink cartridges, mouse pads, etc.), they used calculator-style serial numbers, until at some point they changed the serial number scheme altogether.

[aarong]

just for fun...

they even dress alike