Can we have RPN back?

[Tim Wessman]

(03-27-2014 02:31 PM)orcinus Wrote:  The answer to all of these is simple - it *should* behave like it has since hp48.
Namely - like RPL.

I think you missed one important detail which is the discussion was around RPN (classic) and not RPL. RPL does indeed address those issues, but what was being asked was a basic, 4 level traditional RPN equivalent.

[orcinus]

I know. I'm just implying that that boat has sailed long before the Prime (with the introduction of the G calculators).
And that there is no point in re-inventing the wheel, as "solution" already exists and has been proving itself on daily basis - since the day RPL was introduced

Edit: On top of that, RPL is a natural extension of RPN. No one's forcing you to use >4 stack levels.

[Jake Schwartz]

Quote:I also cannot find a reference to RPL in the HP-28 and HP-48 series manuals, only RPN.

In case this hadn't yet been mentioned, the August, 1987 issue of the Hewlett-Packard Journal (dedicated primarily to the 18C/28C) has an article by Charlie Patton, titled "Symbolic Computation for Handheld Calculators" starting on page 21, where he states: "The ultimate result is a combination of features from both Lisp and Forth that we call the ROM-based procedural language, or RPL." He uses "RPL" throughout the remainder of the article. And Bill Wickes and Charlie Patton refer to it as RPL in their June, 1991 HP Journal article "The HP48SX Scientific Expandable Calculator: Innovation and Evolution". Also, I recall Bill Wickes' HP28C presentation at the PPC Washington DC chapter meeting on February 5th, 1987 where he introduced the term RPL, calling it "Reverse Polish Lisp". (I lugged my 20 pounds of primitive video gear a hundred miles south from New Jersey to the University of Maryland to videotape that one.....it was definitely worth it)

Jake

[John R. Graham]

(03-27-2014 04:08 PM)orcinus Wrote:  ...Edit: On top of that, RPL is a natural extension of RPN. No one's forcing you to use >4 stack levels.

Arguably, this is true. I like the extensions. However, RPL (Entry RPN) isn't a fully compatible extension of legacy RPN. That's what the OP was asking for: a compatible legacy RPN mode for Prime. I don't want it, but I understand the request.

The two major differences are (I believe):

• Behavior of stack lift. Starting with an empty stack, "2 [Enter] x" results in 4 on legacy RPN calculators and an error on RPL calculators (and the Prime).
• Auto-copy of T. As operators consume the contents of the stack, on legacy RPN calculators, the contents of T is duplicated into Z so that the stack never truly empties. (In fact, the stack always contains 4 numbers.) On RPL machines, the stack can actually empty, resulting in operation not being able to complete for lack of arguments.
  

Of the two, I think the first is the most important behavioral attribute to the legacy RPN crowd. I've taken advantage of the behavior on the 35/67/97/41 myself, but I think the more recent behavior is more internally consistent, even though (gasp) it takes an additional keypress for some operations.

- John

[Ivan Rancati]

(01-26-2014 11:53 PM)Craig Thomas Wrote:  The reason I'm not using my Prime as an engineering calculator is simple.

x to the y key

I'm a bit confused here. Was the label on the key not changed already with the HP-45 in the early 70s?

HP-45

Quote:The HP-45 also added 10^x and replaced x^y with y^x.

[Thomas Radtke]

(03-28-2014 06:29 PM)Ivan Rancati Wrote:  Was the label on the key not changed already with the HP-45 in the early 70s?

Not only the label changed but also the order of arguments. The 35 had a true x^y function while all later models had y^x.

[orcinus]

(03-28-2014 03:34 PM)John R. Graham Wrote:  [*]Behavior of stack lift. Starting with an empty stack, "2 [Enter] x" results in 4 on legacy RPN calculators and an error on RPL calculators (and the Prime).

Nope. Enter behaves as DUP when there's nothing on the entry line.
On RPL calculators (confirmed on a 48 and two 49s) and Prime (at least in the emulator). That's how it always was, AFAICR.

(03-28-2014 03:34 PM)John R. Graham Wrote:  [*]Auto-copy of T. As operators consume the contents of the stack, on legacy RPN calculators, the contents of T is duplicated into Z so that the stack never truly empties. (In fact, the stack always contains 4 numbers.) On RPL machines, the stack can actually empty, resulting in operation not being able to complete for lack of arguments.

I don't think i understand this one (bear with me, my history with HP begun with RPL, not RPN). Are you saying that on the classic RPN models, as you continue hitting DROP, the contents of T fills out the stack levels beneath it? Isn't that an accident waiting to happen?

[Tugdual]

You know, the kind of things I also miss on the Prime, on top of a decent RPN (and RPL though I have to admit that 90% of my RPL programs can easily be replaced by a simple function on the Prime, but I digress ) I miss something as simple as STO 0 and then later RCL 0. I still don't get it how impractical it is to simply store and recall a value.
So we now have Shift Sto Alpha A instead of a straightforward STO 0 in textbook mode.
In RPN I still didn't figure out how to store something...
Another extremely basic thing that I miss badly is the Delta % key. Was sooo practical and easy so let's remove the key.
Seriously HP...

[orcinus]

(03-29-2014 12:21 AM)Tugdual Wrote:  In RPN I still didn't figure out how to store something...

On the Prime?

Put something on the stack, put the variable name on the stack (mind the single quotes or you'll recall the variable value instead), hit Shift + EEX (STO). That's how it always worked on RPL machines, however...

On those, user variables were listed in the menu and you could store a value directly via Left Shift + soft key and recall them by just hitting the soft key. Also, those had the single quotes directly available (unshifted) on the keyboard, unlike the Prime.

So yes, not very convenient...

[John R. Graham]

(03-28-2014 11:42 PM)orcinus Wrote:  Nope. Enter behaves as DUP when there's nothing on the entry line.

I didn't say it didn't. Try the example as described and you will get the results I described as well. Honest.

- John

[orcinus]

Ah, sorry, wasn't paying attention, i autoassumed you meant 2 ENTER ENTER *
Are you saying that 2 gets DUP'd one stack level up automatically if another parameter isn't provided?

If so, how is that good? What guarantee do you have something wasn't left on the stack from a previous calculation?

[Tugdual]

(03-29-2014 12:45 AM)orcinus Wrote:  

(03-29-2014 12:21 AM)Tugdual Wrote:  In RPN I still didn't figure out how to store something...

On the Prime?

Put something on the stack, put the variable name on the stack (mind the single quotes or you'll recall the variable value instead), hit Shift + EEX (STO). That's how it always worked on RPL machines, however...

On those, user variables were listed in the menu and you could store a value directly via Left Shift + soft key and recall them by just hitting the soft key. Also, those had the single quotes directly available (unshifted) on the keyboard, unlike the Prime.

So yes, not very convenient...

Oh that is the quote thing that I missed, thanks for your explanation.

So basically, to store Ans in A:
Non RPN version: [Shift] [EEX] [Alpha] [Vars]
RPN Version: [Shift] [+/-] [Alpha] [Vars] [Enter] [Shift] [EEX]

Compared with most old schools HPs (including the not old school 34s)
HP15C: STO 0
HP34S: STO 00

Right... pretty explicit.

[John R. Graham]

(03-29-2014 05:00 AM)orcinus Wrote:  Ah, sorry, wasn't paying attention, i autoassumed you meant 2 ENTER ENTER *
Are you saying that 2 gets DUP'd one stack level up automatically if another parameter isn't provided?

If so, how is that good? What guarantee do you have something wasn't left on the stack from a previous calculation?

It has to do with lack of an entry line. Entry occurs directly into X. So, as you start entering a new value, X is automatically lifted up the stack to make room for the entry. The behavior of the [Enter] key is even more nuanced. It does these three distinct things:

1. Terminates data entry of the number into X.
2. DUPs X into Y (and, of course, first, Z into T and Y into Z).
3. Disables automatic stack lift for the next entry. Any functional operator will operate on the stack and re-enable automatic stack lift.

So, if I want to multiply 2 by 3, when I start with "2 [Enter]", both X and Y contain 2, but when I continue, typing "3", now X contains 3 but Y still contains 2. Finally, typing "x" (multiply) will consume X and Y, leaving the product in X and re-enabling automatic stack lift so that, when I operate further on the product, it won't be lost. The HP-35 and HP-41C manuals (and others, I'm sure) describe this behavoir in some detail and show the types of keystroke shortcuts that result.

Regarding something being left on the stack from prior calculations, that's never a problem on the legacy RPN calculators. Previous results are never mixed unless you explicitly mix them. Furthermore, since the stack is fixed in size, it never gets cluttered with (too many) old, unwanted results, something that can be a problem with the RPL family.

Now, all that said, I think the RPL family implementation of RPN is more straightforward, and I'm quite used to it. However, if the old automatic lift functionality had been present as an option on the RPL family (enabled, say, by a flag), I might've enabled it. Who knows?

Tim, please, if you're even remotely considering this, don't bring along the concept of a fixed 4-level stack with auto-copy of T (or else make that a separately-controllable option). Legacy stack lift behavior plus infinite typed stack seems sweet.

- John

[Craig Thomas]

(03-28-2014 06:29 PM)Ivan Rancati Wrote:  

(01-26-2014 11:53 PM)Craig Thomas Wrote:  The reason I'm not using my Prime as an engineering calculator is simple.

x to the y key

I'm a bit confused here. Was the label on the key not changed already with the HP-45 in the early 70s?

HP-45

Quote:The HP-45 also added 10^x and replaced x^y with y^x.

On the Prime,if using RPN mode, and if you read what's on the x to the y key, and assume it calculates 'x' to the 'y' in the manner of HP's I've used for 30 years, you would be wrong. The x and y have nothing to do with the old concept of an x and y register. They work exactly backwards compared to my 30 years of HP use. HP21, HP25, HP29c(?), HP41, HP48S, HP48SX, HP48GX, HP15C, HP32sii and a couple of others.

The same is true of the nth root of x key. Treating n as coming from a y register and x as coming from an x register works exactly backwards from how the key actually calculates.

Which is why I put forth the idea of a Geezer RPN mode that would make these keys 'correct' for (cough cough) experienced engineers such as myself. Call it 'legacy rpn' perhaps.

I don't memorize the keys as apparently some do. I actually look at them for a second for the clue as to how they operate and what they operate on. The Prime screws this up for me.

Some people cloud this argument with talk of limitless stacks vs 4 level stacks. It doesn't bear on this particular complaint. The 48 has a fine unlimited stack and the key labels perfectly correspond to X and Y registers making it completely clear which numbers are used for calculation.

[HP67]

(03-28-2014 11:42 PM)orcinus Wrote:  I don't think i understand this one (bear with me, my history with HP begun with RPL, not RPN). Are you saying that on the classic RPN models, as you continue hitting DROP, the contents of T fills out the stack levels beneath it? Isn't that an accident waiting to happen?

No, there is no DROP on RPN calculators, only (implied) DUP, and SWAP. That's it. You want more than that you write a keystroke program and IIRC you still cannot manipulate the stack a la RPL.

[HP67]

(03-29-2014 12:21 AM)Tugdual Wrote:  Another extremely basic thing that I miss badly is the Delta % key.

I was looking for this last night on my 48s. If it is there I can't find it. I am so used to having this on my 12C and it really does come in handy when you need it.

[Joe Horn]

(03-30-2014 07:07 AM)HP67 Wrote:  

(03-29-2014 12:21 AM)Tugdual Wrote:  Another extremely basic thing that I miss badly is the Delta % key.

I was looking for this last night on my 48s. If it is there I can't find it. I am so used to having this on my 12C and it really does come in handy when you need it.

Buried in menus:
48S: MTH PARTS NXT %CH
48G/49/50: MTH REAL %CH

32SII, 33S, 35S, 30S, 10bII+, 20S, 10B, 22S: on the keyboard

[HP67]

Sorry, I meant I couldn't find it on the keyboards. I did find it in the math menus. Thanks.

[RyanB]

The Prime keyboard could be so great for RPN/RPL, what with the enter key properly sized and placed on the keyboard! My dream is a full implementation of 48/50 style RPN stack and menus with a custom keyboard overlay.

-Ryan

[HP67]

The ENTER key should be midway up on the left side of the keyboard. I don't know why they put a large ENTER key on the right side of the Prime...