Re: RPN as a language? Message #5 Posted by Ellis Easley on 24 Aug 2002, 8:58 p.m., in response to message #4 by Chan Tran
I have the SR50, SR50A and SR51A but I only have the manual for the 50A. None of them have parentheses. The SR52 and 56 do have them.
The "sum of products" system must have been TI's first attempt to get around RPN. It reminds me of the "andorinvert" arrangement used in programmable logic devices. Some of the examples in the book require rearranging things. In fact, here's what the first page says:
"The SR50A uses the algebraic entry method to simplify data entry into the calculator. For simple problems, the numbers and algebraic functions are entered into the calculator in the same sequence as they are stated algebraically."
Note the qualification  "for simple problems"
The SR50 and 50A have the same key layout but the difference is more than just the style of the case. They have different PCBs. However, they both give the same result for the "calculator forensics (I think that's what he called it)" benchmark test posted here by Mike Sebastion (I think that was his name): (in degrees mode) 9, sin, cos, tan, atan, acos, asin. The result is ideally 9. I go a step or two further and subtract 9 from the result and multiply by 1,000,000. This lets me see the guard digits (if there are any) and also gives a sort of "parts per million" result.
BTW, the SR50, 50A, and 51A have a very good score on this test, 4.661314 "ppm". Only some of the later HP's give a better result among my calculators  HP 71B, 48SX, 48GX, 32SII and 20S all give 1.35733. HP 67, 34C, 41C and 15C all give 417.403. HP35 (original ROM) gives 2983.113, HP45 gives 4076.644, HP25 gives 4076.649. TI SR52 and 56 give nearly the same number as 50 except there appears to be one less guard digit. The main purpose of the test, according to the guy, is to identify calculators that may have the same firmware inside, but it also gives some indication of the precision an/or accuracy of a calculator.
