How to identify HP-49g+ production runs

[Eric Rechlin]

The 50g units are all in theory the same. The later ones come with a canvas case that may be more durable than the synthetic leather cases from the earlier ones, but I haven't seen enough out there to know how they hold up. The latest 50g calculators in my experience tend to have slightly less reliable keyboards than the earlier ones, probably because the manufacturing line was getting old and things were getting out of tolerance (that's just a guess). There is no serial number threshold or anything, just out of dozens and dozens that I tried over the years, virtually every single one in the early years (first 5-7 years of production or so) was perfect, but towards the very end I occasionally ran into ones where one of the keys didn't always respond unless pressed just right.