35s program checksums

[rprosperi]

(01-23-2015 05:59 AM)MarkHaysHarris777 Wrote:  Thank you for your candor, and for some hints moving forward. I am going to be diving into this a bit in a week or two when I can get my hands on a second unit. Without the second unit for control|compare|contrast it will not be possible to speculate further. I truly suspect that for *everyone* the bug is simply not understanding how the checksums are calculated and what the rules are. Once we iron that out and publish it on the site somewhere folks can have a better confidence in the length checksum system. I too agree its a pretty neat system.

Thanks Marcus for taking on this job, hopefully your investigation will reveal some pattern which makes the checksum variations to be clear and maybe even predictable.

I think many of us want to use and love the 35S more, but its hard to shake the loss of confidence that occurs when one encounters this checksum thing (usually leading to huge, frustrating amounts of time double- & triple-checking code, etc. only to eventually discover it's fine, it was a 35S problem, not yours).

The many other bugs are well documented, but are far less likely to be issues for most use, but the checksum thing was, for me, a deal breaker. As some have pointed out, we all got along fine with long programs in older machines before the checksum feature even exisited, but in the 35S case we have something staring at us specifically saying "this program is NOT correct" (compared to source that was copied).

Given the 35S role as the last RPN Calculator HP will make (thus HP-35 "bookends") it is particularly sad that early on, HP chose to not fix the problems, thus more and more 'bad' machines enter the market, making a recall (or whatever) even less likely due to the increasing liability. No doubt it occurred during a management change in the calculator group (statistically likely anyhow...). Given the real cost numbers and HP's focus shift from quality to operating margin, I'm not sure I would have made a different decision were I in that seat, but I'd like to think I could have argued that treating it that way would guarantee it would be the final machine of that type.

Anyhow, thank you Marcus and Didier for giving me good reasons to take out my 35S and love it a bit more. I look forwad to your results.