|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
I'm in the process of designing a (non-programmable) 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 ...
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., HP-48) dynamic-depth stacks. It is unneeded for RPN's fixed-depth 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 HP-41/42S models add direct access to stack elements and a VIEW command.
should I have X^Y or Y^X, how to implement base-N modes, is LAST X useful
x^y was offered only on the HP-35, 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 base-2, base-8, and base-16, while base-10 remained floating-point with conventional BCD math.
LASTx is very useful for error recovery and as a convenient "stack-extender." RPN models lack RPL's UNDO function.
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 storage-register arithmetic functions, such as STO+3 and RCL/2, giving extended functionlaity without additional functions on the keyboard.
Would a deep stack be better than the basic 4 level type? if so how deep and why?
A user-settable fixed stack up to 9 or 19 elements deep (e.g., [STKD] 9 or [STKD] .9), with default of 4, would be useful.
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 HP-42S were present because the temporary menu-line display in the bottom row necessitated the identification of what was displayed above. Space for the indicators was made available by its fine-grain 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 single-step execution on the HP-32/42 models.
I generally prefer a larger, easier-to-read one-line display on non-graphing models, although the two-line display has some advantages.
Edited: 12 May 2007, 2:12 p.m.