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).