Enter RPN: R47 vs DM32

Caveat

This is a living document containing my burgeoning thoughts on the SwissMicros R47 as contrasted with the DM32. I expect this document to grow considerably as my explorations proceed. If you are looking for settled conclusions, turn away; this document contains naught but flittering thoughts frozen in place at the moment I committed them to the wiki. I fully expect that some of what you find here to be objectively incorrect out of my own ignorance, which you have the opportunity to experience because I need to get them into durable form before I can refine them properly, lest I lose them entirely.

Lucky you. 🤓

Why Both?

By sheer happenstance, I purchased a SwissMicros DM32 mere months prior to the public release of the R47 hardware. Had I known availability of the R47 was this close, it is possible that I would have waited, limiting myself to purchasing one really expensive boutique calculator, but since I now have two, it is natural to compare-and-contrast.

While I am not advocating that others follow this path, I can already see that there may be reasons why another might choose to have both, without needing a similar failure of foresight to retroactively justify that decision.

Others might read this document to find out which single machine to buy. I can tell you this much already: although the R47 covers 100% of the functionality of the DM32, there is value in the latter’s relative simplicity.

Establishing the Landscape

Although the SwissMicros DM32 is intended to behave much like the Hewlett-Packard HP-32SII, it is largely a first-party design. This modern hardware creation does have the same buttons in the same arrangement as the 32SII, with the same labels, giving the same broad effects, but everything else differs. The SwissMicros hardware platform is generations past what HP had at hand in 1991 when they released the 32SII, and the firmware behind it is a complete reimplementation, not a copy of HP’s old firmware running inside a Saturn CPU simulator. All this shows in the calculator’s user-facing behavior, giving the modern device a distinctive “SwissMicros” feel. To call it a mere clone would miss the target by a mile.

My understanding is that this is the same base hardware platform used for the DM42n and the R47. The entirety of the physical difference is down to the text on the faceplate and button faces, plus minor details like where the colorful shift keys are placed. Everything else is a matter of which firmware you happen to have loaded.

Availability of this semi-open flexible platform permitted the creation of the C47’s ancestor projects, resulting in the R47 production version. Because I have no experience with the earlier DM42 conversion efforts, I will refer solely to the R47 from here on, being the device I have at hand.

Speaking of conversion efforts, I do believe it possible in principle for the R47 team to port their code to the DM32 platform, but that would require a near-complete remapping of the buttons, plus a new bezel design. I completely understand a wish to restrict expenditure of finite volunteer efforts to a single base platform.

Broad Impressions

Different minds = different results. Although these multiple teams have been developing atop the same hardware platform, their efforts have yielded two very different experiences in the DM32 and R47.

An excellent place to start exploring these differences is the six soft menu selection buttons, which the DM32 keyboard adds above those giving access to the HP-32SII functionality.

But first we must to dig back to its predecessor, the HP-32S. This was not Hewlett-Packard’s first menu-driven calculator,¹ but there is a strong distinction to be made relative to the HP-32S’s direct-line predecessors in the Voyager series, where the closest you got to menu-driven behavior was the HP-15C’s TEST button. HP perpetrated that botch because the functions they wanted to stuff into the 15C over the earlier 11C crowded all but two of the numeric tests off the main user interface.

The two-line display in the HP-32S shows a much better way to handle this crowding: explicit front-side visible menus. The main oddity remaining here is that HP chose to repurpose the calculator’s top row of buttons so that with the MODES menu up, pressing the √𝑥 button selects the DG item, putting the calculator into “degrees” mode. While this is somewhat obscure, it is a straightforward enough hack that one may guess at how to handle the ⬇︎ indicators on the HP-32S display’s bottom line without needing to read the manual to learn the secret.

As we will see, the DM32 resolves this obscurity, but for now let us observe that the HP-32SII then took that idea and ran with it by adding a second shift button to the lone 🟧 shift sported by the HP-32S, then packed its menu-driven functionality more tightly. Whereas the HP-32S had sixteen 🟧-shifted buttons that pulled up menus, averaging 3.25 functions per, the HP-32SII pared that back to fourteen menus but increased function density to an average of 4.4 per. This counts top-level choices only, not doubly-nested functions like on the TESTS menu.

The DM32 clones that behavior, but it then adds a row of doubly-unlabeled soft keys above this, having the same effect within one of the emulated menus. Other HP calculators label these F1-F6, a convention I will mimic here for lack of any other way of referring to them other than ordinally.

This brings us to one of the few design errors in the DM32. In every other device I have used with soft menu keys, they are paired with on-screen labels to show what pressing each button will do, but on the DM32, this occurs only in places where it is emulating HP-32SII menus. The thing is, these soft keys have other functions in the DM32, and these extended functions are never labeled on-screen. You have to read the manual and memorize what you can, or discover by accident what these buttons do in these situations.

While there is hope that this will be fixed in a future firmware release, the point I wish to make here is that the R47 takes the opposite tack, in spades, with bells and stars on. As I understand it, the original intent was to have a 3-level menu system where the same six unlabeled soft keys provided by SwissMicros on the top row would pick from six menu items, much like on the HP-32S. But then atop this, the idea was that you could precede one of these presses with an 🟧 or 🟦 shift button press to select from up to twelve more functions on the two menu rows above this. While the R47’s predecessors might once have been this straightforward, the end product now has scrolling pages of menus in places so that a single menu might give access to dozens of functions, not limited to the original intent of 18, max.

This, then, is why I want a proper user manual for the R47. The present function indices allow a knowledgeable user to back-trace menu paths, but only when you can find out what your desired feature is called to begin with. I’ve had my R47 at hand for less than a day as I write this, yet already I find myself unable to count the number of times I’ve tried and failed to find a function with my first few searches.

Yet it is there. Not once have I completely failed to find a given function.

This brings me to my first broad conclusion: the R47 is the type of tool that a professional uses with the certain foreknowledge that any limitation encountered in using it is more likely to be in the imagination or skill of the user than in the scope of capability offered by the tool. The calculator’s programmability will cover most rare exceptions, and where that runs out of steam, you have the option to modify the firmware’s source code and build what you need.

The DM32, by contrast, is a generalist’s tool: it is “enough calculator” for a good many professional use cases, but a more inherently limited one. What we gain in exchange is a tool that that is fully documented yet simultaneously straightforward in operation to the point that an experienced user will not often need to resort to that manual. This is a valuable tradeoff. If your needs fit within the DM32’s scope and are likely to remain so, it becomes difficult to recommend the R47.

Menus, Menus, Menus

And yet, the DM32 is not without flaws. I covered one biggie above, but another is that the labels on its faceplate do not call out which functions pull up a menu and which take direct effect. On the classic HP machines, these had a darker or lighter background, depending on the generation. I’ve always considered that somewhat ugly as compared to the cleaner design of the HP-20S, a lower-spec family-mate of the 32S, but I do have to concede that these shaded boxes are helpful.

The R47 solves this in a more aesthetically pleasing manner while managing to be even clearer: a gray border surrounds labels where a shifted key combo will pull up a menu.

I have no wish to try and count all the menu items you can access this way on the R47. I am quite certain the average density would be well above the 4.4 calculated above. The point here is that finding all that functionality is a challenge, especially given the current state of the documentation. Realize, however, that this will continue even in an indefinite future where we have ideal documentation. As a wise general once said…

Quantity is a quality all on its own.

This is one of the reasons I admired and stuck to the HP-20S for so many years, despite knowing about RPN and admiring it also: there is value in having every function of the calculator exposed on the front panel. More functionality is great, but only if you can first find it, then access it quickly enough to be worth having.

My experience of the R47 menus on this front has been mixed, so far. In several cases I have been able to puzzle out the location of an item merely by scanning labels and making educated guesses. In others, the eventual place I found a function has been a surprise, sometimes of the WTF order. An excellent example of this is the calculator’s system menu, because it hides behind the obscure acronym DMCP, after the SDK referenced above. This in turn is the first unshifted function on the first page of the 🟧 PREF menu. Only some of the items on the resulting DM Calculator Platform menu are preferences; others show information about the calculator, leading us to misremember this menu’s location as under 🟦 INFO. Others have neither to do with user preferences nor passive displays of information, and it is these which have the best reason to be on a “DMCP” menu, but then where should it be if not under PREF or INFO?

I ask rhetorically, to show the problem, not to solicit a post facto explanation.

Contrast the DM32, where essentially the same stuff is on 🟧 SETUP, a pure extension to the HP-32SII keyboard layout. This label makes sufficiently reasonable sense that one is not surprised by most of the menu’s contents. More, it’s labeled right there in bright orange, ready to be discovered.

Trigonometry

One of the things making me wish I had been involved at a time early enough to influence the direction of the C47 is the TRG menu. It is my belief that this has never been done better than on the HP-28S, where for one thing they found space to spell it out, TRIG.

I get why the project members collectively chose to elevate these to top-level functions, but if it had been me in charge, I would have arranged the present TRG menu thus:

SINC	SINCπ	ATAN2
⇒D.MS	.ms⁻¹	→R	→P	⇒MULπ
DEG ○	RAD ●	GRAD ○	⇒DEG	⇒RAD	⇒GRAD
SIN	COS	TAN	SIN⁻¹	COS⁻¹	TAN⁻¹

Not only does that give access to the six primary trigonometric functions without further shifts, it would open up six shifted front-panel locations for important things like SETUP. It also shoves the obscure sinc functions and atan2 off to a second page, where they ought to be, when properly ranked against what I have put on the first page.

But they didn’t ask me, did they? 🤓

Navigation

There’s a wry old observation that ran around Silicon Valley before the PC police stamped it out:

You can always tell the pioneers; they’re the ones with all the arrows in their backs.

In our present comparison, the pioneers are the ones with all the arrows on the front, ha ha!

The R47 does navigation right, for the most part.² It dedicates two of its precious top-level keys to up/down arrows, and it uses the six soft menu buttons to cover the horizontal dimension. Add to this the two shift keys, and you can access its many menus with reasonable ease.

Now let us observe the mess that is the DM32’s navigation scheme, where at least three prior designs were thrown together into a mishmash:

HP-32SII: This historical forebear to the DM32 offered a single method, 🟧 7/8, where HP in its wisdom tucked the down/up arrows away.
DMCP: Because HP’s questionable design decision requires a lot of shifts in tasks like program editing, SwissMicros programmed two of their soft buttons to give the same function without the shifts (F5/F6) but only while in PRGM mode or inside the SETUP menu. Elsewhere, these buttons change to do other things, and because they are doubly-unlabeled, one may well be uncertain what they will do instead!
HP-32S: In an apparent bid to merge in the historical 32S behavior, where the arrows were on a dedicated button, pressing the 🟧 key on a DM32 sometimes moves a selection point down. HP moved these arrows above the 7 and 8 keys per item #1 above, then bumped the 🟧 shift up into the space that made available, allowing the prior space to be taken over by the new 🟦 shift key.

The DM32 creators appear to have thought, “Right, what is now the 🟧 shift used to be the arrows, and pressing this button unshifted gave the ‘down’ function, so let’s do that, merging both behaviors!” The problem that then raised is, does pressing 🟦-🟧 result in an upward movement of the selection, as 🟧 ▼ would have on an HP-32S? That breaks the historical HP behavior that pressing one shift cancels the other. What they chose instead is to make the complementary command the XEQ key, which has no faceplate label to indicate this surprising behavior.
Help: The DMCP help system has a further surprise: it repurposes the four basic operator keys as page up/down and line up/down, in that order, top-to-bottom. These also work in DMCP menus, but not elsewhere since they are needed to provide the labeled arithmetic functions.

What this leads to is poor habit-building. The user may be in the middle of editing a program, using the F5/F6 combo to avoid the hassle of the 32SII’s shifted arrow design, but then go into the Help to look something up, where F5/F6 now means something else, which is not labeled on-screen. They may become irritated enough by this to seek out another way which they can safely build a habit on and find the 32SII arrows, but on pressing 🟧 to employ them, they find the cursor immediately goes down even though this historical 32S behavior is not marked anywhere on the faceplate. 🤬

Being based on the same DMCP5 platform as the DM32, the R47 inherits the +/- behavior in the DMCP menus. There appears to be no on-board Help at this time, so I have observed no repurposing of ÷/× as page up/down. Everywhere else, the two dedicated arrow buttons rule the day. This is a significant day-to-day improvement. It is placement one can build solid muscle memory on, and when habits fail, it is immediately rediscoverable.

Future Directions

I intend to give deeper examples comparing and contrasting the operation of these two calculators here, but for now, I bid you adeiu.

(You may now wish to return to my R47 article index.)

License

^{^} I believe that honor goes to the HP-18C, off on a parallel development track.
^{^} There appear to be remnants of historical designs in the firmware I have running here, 0.109.02.07b12. See for instance the 🟦 P.FN menu, where repeatedly hitting F6 cycles through all three pages of the menu. This is inconsistent with the rest of the menu design, where you would need to use the up/down arrows instead, and further menu pages would be indicated by wee arrows above the upper left corner of the third menu row.