I've been using my 35s for basic hand-calc engineering work since late August 07.

I kept about four programs (3D vector cross product, area moment-of-inertia, a Clear All: vars stack summation code, and some obscure stopwatch that I was playing with).

I also kept 4 eqns: TVM, and 3 engineering eqns.

I recently entered a new equation which contained a few unevaluated numbers (for example: 3.2*8*(X+81)/15 + ...). The calculator exclaimed MEMORY FULL when I invoked the solver. I simplified the equation by pre-calculating the constant values into a lumped coefficient, and it was able to solve w/o the MEMORY issue.

I checked MEM, and was surprised to see 640, and 731 bytes for vars and prog remaining free respectively.

So, I summed all and found: BYTEprog + BYTEvars + 640 + 731 != ~30k. I had to reset, and am now not very motivated to re-enter those programs and equations.

I ask this question: Why should I have to re-enter my programs and equations, and (MORE IMPORTANTLY) spend time validating that I have indeed not made any errors, since the check sum is faulty as well?? Furthermore, how soon will this occur again (of course, I don't know).

Are you sure that you didn't accidently use up the memory by allocating unnamed indirect variables? AFAIK, its not enough to store a zero in an indirect variable to make its memory available again. You have to use one of the clear commands for that purpose.

Not to be nosey, but what are the engineering equations you have stored in you 35S? Just curious.

I have 2 35S's and I use them everyday! Now if HP could just make a HP 50G+ with a BIG Enter key I would be in Heaven.

Jack,

I keep (kept) some basics like a fastener spacing equation that I derived based on fastener count, pitch, fastener row length, desired (or permitted) edge distance at each end (this I found myself frequently calculating out on the shop floor during preparation for assy of a space vehicle that I was working on earlier in the year. It was a daily matter to be crawling around, and the 35s was small enough to warrant field use :)

The other one or two were simple ones, like the moment of inertia for a thin-wall circular tube, and the occasional equations that arise for a specific task that lingers for a week or so (you know).

Yes, I'd like the 50g more with the large ENTER key. But above all, the quality of the earlier calcs is what I want. I'd truly be happy to slightly compromise certain things, given sufficient user customization via menus, etc, if I could get a new HP RPN that would be expected to last 10+ years, and have at least a single reliable backup feature (usb, sd, else?)

/EL