General Category > LisaList2
Lisa Tank Problem
compu_85:
Hm ya, the 0th day of 1983?? ???
fri0701:
--- Quote from: compu_85 on August 30, 2024, 07:30:13 pm ---Our "tank problem" math is way off because a ton of applenets got reused.
FWIW, I basically trust the 90,000 number.
--- End quote ---
I've been working with a new idea of how to estimate this number more accurately.
If you graph AppleNet# vs Date, you'll see that there are bands of time where the AppleNets strictly increase, and then at some point, the starting number seems to "reset" to a different random value and continue up from there. The duplicate AppleNet numbers we've found appear in different "bands", so it appears they overlapped each other from time to time.
I took the dataset and divided it up into these "monotonically increasing bands" (where the AppleNet numbers strictly increase), performed a tank problem calculation for each band, and added them all up. This analysis produces a total Lisa production count estimate of 52,876 - which is more in line with what we're seeing than ~10k when calculated over the entire dataset.
Do note that some bands have only a few AppleNets in them, and when you add more numbers to the middle of a band the tank problem estimate tends to decrease, so this likely tends to be an overestimate and is subject to change as we discover new machines.
I'll keep adding new machines as I find them and see if the number changes dramatically. Food for thought for anyone else interested in this very specific statistics problem :)
compu_85:
Nice work! I'd been thinking about doing something similar, or at least mapping out the possible overlaps, and also try to break down known systems by factory.
As Lisas transition from vintage computers to rare collectible objects I think the work we've done to catalog known systems will be valuable. It's a good way to spot fake Lisa 1s.
-J
fri0701:
Adjusting my calculation to skip segments of days where we have yet to track a single Lisa having been produced, the tank problem estimate goes down significantly to 40,824.
Interestingly, there seem to have been no Lisas produced from March 15 - June 5th, 1984 (the longest empty span we've seen so far); especially curious since the Lisa 2 line had just been announced alongside the Macintosh a few months earlier in January. Perhaps Apple had "overproduced" Lisas to such a degree that they decided to temporarily halt production, an early indication that the whole Lisa line was in significant trouble?
ried:
One more for the tracking sheet: https://imgur.com/a/FcQgtJJ
It's a Lisa 2/5 which appears to have originally been a Lisa 1. Difficult to make out some of the numbers.
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