Re: Ideal RPN calculator features... Message #21 Posted by Karl Schneider on 11 May 2007, 2:36 a.m., in response to message #1 by DaveJ
Quote:
I'm in the process of designing a (nonprogrammable) RPN calculator, and I am after some opinions on what people would like to have in their "ideal" RPN calculator.
Any input is appreciated.
Hello, Dave 
If input ye ask, input ye shall receive ...
Quote:
Right now I have a 4 level stack with T operating as a constant, STO, RCL, DROP, ROLL UP/DOWN, SWAP etc
DROP is stack operation for only RPL's (e.g., HP48) dynamicdepth stacks. It is unneeded for RPN's fixeddepth stack. SWAP is the RPL term for x<>y.
Classic RPN gets by just fine with the elegant simplicity of "x<>y" and "roll down". "Roll up" is a convenient nicety, useful mainly for programming. The HP41/42S models add direct access to stack elements and a VIEW command.
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should I have X^Y or Y^X, how to implement baseN modes, is LAST X useful
x^y was offered only on the HP35, perhaps because it lacked a 10^x function and common logarithms:
x [ENTER] 10 x^y = 10^x
y^x, however, is more natural and consistent with subtraction and division.
Most scientific RPN and AOS models starting with the Pioneer series (in 1988) offered integer arithmetic in base2, base8, and base16, while base10 remained floatingpoint with conventional BCD math.
LASTx is very useful for error recovery and as a convenient "stackextender." RPN models lack RPL's UNDO function.
Quote:
Would you prefer just one memory using STO/RCL, or multiple constant memories called something like M1, M2, M3? Are memory operations like M+ and M useful? and should it operate on STO/RCL register or be seperate?
If more than one memory is offered, M1, M2, M3 with M+ and M will make for a busy keyboard. Most models have storageregister arithmetic functions, such as STO+3 and RCL/2, giving extended functionlaity without additional functions on the keyboard.
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Would a deep stack be better than the basic 4 level type? if so how deep and why?
A usersettable fixed stack up to 9 or 19 elements deep (e.g., [STKD] 9 or [STKD] .9), with default of 4, would be useful.
Quote:
I will have a two line display, how do you think that display should best be utilised?
At the moment I have the Yreg on the upper line and Xreg on the lower. Should I waste display space showing "X:" and "Y:" at the front, or is that distracting and redundant?
Should the display simply "switch" to displaying Z: and T: or should it "slide" up and down?, or not have that feature at all?
The "X:" and "Y:" indicators on the HP42S were present because the temporary menuline display in the bottom row necessitated the identification of what was displayed above. Space for the indicators was made available by its finegrain LCD display.
Up/down scroll arrows would make possible viewing of the stack without modifying it, but is hardly needed with a short stack, roll down, and the VIEW command. The down scroll arrow, however, is used for singlestep execution on the HP32/42 models.
I generally prefer a larger, easiertoread oneline display on nongraphing models, although the twoline display has some advantages.
 KS
Edited: 12 May 2007, 2:12 p.m.
