HP35s RPN Series # 3 [ENTER]

[MarkHaysHarris777]

(02-18-2015 10:04 PM)Thomas Klemm Wrote:  

(02-18-2015 08:24 PM)MarkHaysHarris777 Wrote:  1) other programmable calculators of the era (Wang 700, others) had register manipulators, but no [ENTER] key (certainly nothing like the HP RPN [ENTER])

Using the Wang 700 Programmable Calculator Simulator I have the impression that the [↑] key pretty much does what the [ENTER↑] key does: copy the number from the x register to the y register.

Yes; but without all of the [ENTER] key baggage. The Wang did not have a stack. It had a rich set of register manipulators, and again, if you could figure out a way to get your numbers into the X and Y registers you could do some maths on them!

(02-18-2015 10:04 PM)Thomas Klemm Wrote:  I assume that's similar to how the 3-level stack of the HP-9100 worked:

I never got the pleasure of using the HP-9100; I believe it had a three level stack, but I cannot offer any clue how it worked, sadly.

(02-18-2015 10:04 PM)Thomas Klemm Wrote:  The HP-engineers came up with a clever solution for this problem.

Oh, no doubt; very clever (as they say, the rest is history)

(02-18-2015 10:04 PM)Thomas Klemm Wrote:  Sooner or later you want to duplicate a number. You may call it what ever you like: [↑], [ENTER↑] or [DUP]. But the [+] key doesn't help here.

I disagree. The truth is, if you'll be honest about it with yourself, you 'want' to duplicate a number with the [ENTER] key because you 'can,' not because its necessary. Well, on the surface, if you want to duplicate a number:
[2] (auto stack lift) [X] (auto stack drop) {problem solved}

I agree with you that the [ENTER] key (and its quirks) may be leveraged in many interesting ways (as I stated in my article), but its not necessary. In other words, there are alternate ways of manipulating the stack and registers without using the [ENTER] key.

Having said that, the only reason I point out the [ENTER] conundrum is to help new users (and new programmers) to understand what is really happening behind the RPN stack and [ENTER] methodology.

PS Thanks for pointing me into the Wang emulator again... brings back many fond memories (almost chokes me up to see it again).

Cheers,
marcus