Motivations

Shortly after unboxing a shiny new SwissMicros R47, you will want to begin customizing it to your preferences. This article will not attempt to provide a comprehensive guide to every configurable item, but rather show the main paths to take and suggest ideas for fruitful spots to visit early in your journey.

🟧 PREF

Start customizing your R47 here. The initial display shows a single-line menu, but there are two more pages collectively containing 5 more lines of configurable items, available via the ⬇︎/⬆︎ keys. There are several items here that are likely targets for Day 1 changes:

• eRPN: This is the modern variant of RPN pioneered on the HP-28S and seen on all later RPL machines, plus ones like the HP 20b and 30b. It is the default on the R47. The easiest way to discern the RPN flavor is to press 4 ENTER ⨉. If you got…

  • …four times the prior value in X, it’s eRPN
  • …always 16 regardless of the prior stack contents, it’s classic RPN due to duplication of the 4 on stack-lift.

  I find eRPN to be an improvement, but then, I do not have deep-grooved habits that depend on that duplication behavior. It’s the opposite with me: on 1-line displays I frequently find myself needing to slow down and think before hitting ENTER lest I create a hidden copy of X up in Y. This quirk of classic RPN is more tolerable on 2-line machines like the HP 35s or 4-line ones like the R47, where I can see my error immediately and recover, but I believe I will enjoy eRPN enough to miss its lack when picking up a vintage machine.

• SSIZE8: This default sets the stack size to 8, in contravention of HP’s longstanding 4-register stack in all non-RPL machines. This innovation goes back to the WP34s, the R47’s oldest lineal ancestor. If you are used to the original HP behavior, you might want to set SSIZE4, but I suggest giving the new method some time first; you might find yourself coming around to liking it.

  Those not stuck in an old groove may still wish to revert to a 4-register stack on the grounds that the R47 display shows the lower 4 stack registers by default, so setting SSIZE4 syncs the display with what goes on underneath. If you press the R↓ key on a machine like the DM32 where there are exactly four stack registers, always visible, observe that the prior X value reappears at the top of the visible stack, in the T register. This also occurs on the R47 with SSIZE4 enabled, but when you have SSIZE8 enabled instead, the prior X moves into D because the upper four registers are called A-D, a fact you can verify by pressing 🟦 REGS.

🟧 DISP

Decimal Number Display Modes

It should surprise no one that the lowest (unshifted) row on the first page of the 🟧 DISP menu gives the most important calculator display modes. These all control how many digits to display after the decimal (radix) mark, and in which number format. The classic HP modes ALL, FIX, SCI, and ENG are here:

• ALL: Show all available digits, within the limits on available LCD space. Lesser calculators run in this mode full-time, as their sole option. Scientific calculators often default to this mode instead of one of the below, out of a wish not to frighten the user with exponents. Exponents do not worry the readers of this wiki, however, and so we proceed.

• FIX: Show a fixed number of digits to the right of the radix mark when a fractional part is given, with rounding. (The R47 always displays integers in full precision given sufficient display space.) In FIX 4 mode, an entry of “12.34” produces “12.3400” on the R47.

  Unlike the modes below, there is no “+1” reinterpretation of the digit count argument because the FIX limit affects the decimal part only. Changing our example above to “12.3456789” produces “12.3457” in FIX 4 mode, including the automatic rounding.

  There are some who use FIX 0 mode to force the calculator to give integer results, but under the R47 type system, there are other ways to achieve that end, such as 🟧 INTS LINT to force a long integer conversion, denoted with a “ℤ” to the left of the number.

  This mode is acceptable when pressing the R47 into use as a financial calculator, where you often want FIX 2 mode for common monetary units. (This should be accompanied by a switch into BCD mode to avoid floating-point roundoff errors.) It is also useful for replicating historical behaviors. Otherwise, for scientific applications, we have better alternatives now. Read on.

• SCI: Shows a single nonzero digit to the left of the radix mark when there is a fractional part, with the given number of digits to the right, scaled using a power-of-10 multiplier. An entry of “.1” under SCI 4 mode shows as “1.0000×10⁻¹” while an entry of “123” appears the same as in ALL mode because there are no decimal digits, preventing the prior rules from going into effect. For this same reason, an entry of “123.4” shows as “1.2340×10²” even though it fits within our 4-digit limit because we included a fractional part. Notice that this gives N+1 total digits.

• ENG: Similar to SCI except that the exponent is always a multiple of 3, in accord with SI unit prefixes: pico, nano, micro, milli, kilo, mega, giga… One learns to read these exponents accordingly. The N+1 digit limit you set gets split to either side of the radix mark to meet this restriction, resulting in anywhere from 1-3 digits to the left, the balance to the right. An entry of “0.1” becomes “100.00×10⁻³” in ENG 4 mode, for instance. If that input happened to be a value in inches, we would read this as “100 mils” or “100 thous” depending on who taught us their preferred scheme, but if it was in meters, it reads as 100 mm the world ’round.

Because this +1 rule applies to several (if not all) numeric display modes, its idiosyncrasies are learn-able. To one who came up on HP calculators, these details may well be ingrained by this point. They even make a type of sense irrespective of historical HP choices: a request for zero digits of precision in SCI mode is nonsensical, so we might as well offset everything by one, right? What that decision bought those first generations of HP calculator users is the ability to have a single-digit precision value on a 10-digit machine, avoiding the need for an explicit ENTER; on an HP-42S, SCI 9 would make it show every digit the machine is capable of displaying, while SCI 0 shows the minimum useful output, a single digit.

Yet I cannot resist opining that this setting scheme is an artifact of a simpler age. 10-digit calculator displays haven’t been impressive for decades. I’ve seen bargain-aisle business desk calculators with 12-digit displays!

HP got there first, naturally, but rather than rethink a scheme inspired by a 10-digit world, they extended the old scheme in an ugly way: SCI .0 means 10+1 digits in HP-speak, and SCI .1 means 12 total.

The R47 preserves this creaky +1 rule for compatibility with old HP RPN programs, if nothing else. Because it is a much higher-precision machine than anything Hewlett-Packard’s calculator division ever produced, the R47 allows 2-digit entry for the precision parameter, making its equivalent to the classic SCI 4 either SCI 04 or SCI 4 ENTER. This precludes the need for the . hack: SCI 11 works as expected.¹

The R47 adds two more modes in a similar vein, which are not unique to it, but are less commonly seen:

• SIG: The FIX, SCI and ENG modes all try to get at the problem of significant figures in different ways, but this mode actually does it the way it is taught in mathematics classes. SIG 4 shows five significant figures in accord with the +1 rule, but it has a useful practical effect. Good applications for this mode typically come out of cases where the final significant figure is iffy. Let us consider measuring an object with a dial caliper calibrated in millimeters, with 1 mm nominal resolution; if the needle doesn’t land directly on one of the dial’s ticks, you can guesstimate down to tenths of a millimeter beyond the reading, adding a fifth fractional digit to your measurement. This last digit is on a sounder basis than a wild guess, but it is not in fact reported by the caliper’s dial.

  Under this mode, entering 123456789 shows the number as given, treating it as an integer constant, but then dividing by 10 shows the result as 12346000: four reliable significant figures plus an iffy “5” rounded up by the following 6, everything else uncertain.

  While this result will make some people uneasy, even to the point of calling it incorrect, it is how real-world measurements actually work. Claiming more accuracy than one’s tools can actually produce leads to overconfidence.

• UNIT: This works in combination with other settings to show unit suffixes to the right of each number, when known. See below for one good use case; there are others.

Fraction Display

The next row down (🟧) is devoted to how fractions are displayed on the R47. Its power in this regard exceeds that of a modern textbook-display school calculator, blowing away classic HP efforts on this front while retaining the utility of RPN. R47 owners no longer need to put up with plasticky Casio Classwiz or TI Mathprint cheapies to get decent fraction handling.

• 🟧 FRACT: Setting this will attempt to show decimal values as fractions, where possible. For instance, entering 0.375 and hitting ENTER will show ⅜ as long as all the other defaults remain untouched.

• 🟧 IRFRACT: Enabling this allows irrational numbers like 0.3̅ to be shown as a fraction, ⅓ in this case. This is, strictly speaking, non-mathematical since the sense of the word “irrational” relevant to us here is “cannot be expressed as a ratio of whole numbers.” Strictly, then, showing a floating-point value as a fraction is always “wrong” whenever the finite precision has run out, even though anyone with any mathematical sense knows what is meant in cases like our example above. When one of these calculated approximations is close enough to be shown as a fraction within the configured limits, this mode allows the R47 to do the right thing.

• 🟧 PROPFR: While this is enabled, the R47 will attempt to show results as “proper” fractions. That is, 1.375 will show as 1 ⅜ instead of ¹¹⁄₈.

• 🟧 DMX: This is the Denominator MaXimum, the limit beyond which the R47 will not go. The default of 64 is good for Imperial measurements, since it is rare to go beyond sixty-fourths, being the rough limit of a cheap ruler’s resolution. You might instead choose 1000 for applications where mils are in common use.

  Especially useful here are multiples of 12, including the ever-popular 60, the basis of human timekeeping and degree-of-angle measurement systems. These numbers have an uncommonly large number of factors, giving the R47 plenty of freedom in selecting “nice” numerators.

Fine Number Formatting Details

That brings us to the top row (🟦) where the first three items bring up further sub-menus for customizing the display of numbers:

• 🟦 IPART: The integer part, broken up by spaces into groups of three, by default. I greatly prefer the classic HP choice,² being from the US, giving me a lifelong familiarity with comma as a thousands separator.

• 🟦 RADIX: This menu not only gives you the classic HP options of a dot or comma as the radix mark, you also have the option of a “waist” level dot, plus options for fixed-width versions of these three. Being a USian, I prefer the proportional-width radix dot — first option, PER. — but please yourself.

• 🟦 FPART: The selection options here are nearly the same as for IPART, with minor changes in offered choices as suits the change in purpose here, affecting the fractional part of the number. Here, I like the 🟦 NSPC␣ option: narrow space. The R47 defaults to the regular SPC␣ which I deem wastes too much…um…space!

The second page of options gives a choice of six common locale settings:

• 🇨🇳 China
  • 24-hour time
  • YYYY-MM-DD dates
  • radix separator: dot
  • integer group size 4, comma separator
  • fractional group size 4, comma separator
• 🇪🇺 Europe
  • 24-hour time
  • DD.MM.YYYY dates
  • radix separator: comma
  • integer group size 3, space separator
  • fractional group size 3, space separator
• 🇮🇳 India
  • 24-hour time
  • DD.MM.YYYY dates
  • radix separator: dot
  • integer group size mixed 3 and 2, comma separator
  • fractional group size 2, comma separator
• 🇯🇵 Japan
  • 24-hour time
  • YYYY-MM-DD dates
  • radix separator: dot
  • integer group size 3, space separator
  • fractional group size 3, space separator
• 🇬🇧 UK
  • 12-hour time
  • DD.MM.YYYY dates
  • radix separator: dot
  • integer group size 3, space separator
  • fractional group size 3, space separator
• 🇺🇸 USA
  • 12-hour time
  • MM/DD/YYYY dates 🙄
  • radix separator: dot
  • integer group size 3, comma separator
  • fractional part ungrouped; no separator

These single high-level settings control multiple display flags in a coordinated fashion, suited to each region’s common rules. There are other associated settings such as which day begins the week, which date the Gregorian calendar took effect in that region, and so forth.

The DFLT setting is the mode the R47 ships in, but it directly controls only these settings:

• 24-hour time
• YYYY-MM-DD dates

…plus a few others. Everything else it takes from the IPART, RADIX, and FPART menu settings. That makes this mode more broadly useful, being tunable to local preferences.

🟧 PREF DMCP

This is the first item on the first page of the PREF menu, but it deserves to be called out specially because it gives access to a key menu for the underlying SwissMicros DM Calculator Platform, atop which the third-party R47 software runs. It offers little in the way of PREFerences, making this a strange place to find this menu, but there is one big exception that brings it to our attention here: the Settings menu item, where you can set the date and time, as well as override some of the locale setting options detailed above.

🟧 PREF CFLG

This is a meta level above both the PREF and DISP menus we toured above, containing all the configuration flags previously covered, those we skipped past, and still more exposed via other paths. It is the master catalog, but by that very fact it should be your last resort for finding a setting.

That said, this is the only way to find obscure settings, a few of which are worth your consideration early on:

• ⬅︎ DROP: When you delete all digits of a partial entry, having this mode set causes that last backspace to take on the effect of the DROP function found on later HP calculators.³ Without this, you have to resort to ugly hacks like backspacing to produce a zero, then hit + to add that to the prior Y value to emulate DROP. Enabling this setting also causes backspace to drop “closed” entries, avoiding the need for the CL𝑥 + workaround.

• 1024ⁿ: Setting this flag and then entering UNIT display mode causes integers to be shown in SI information units: kibi, mebi, gibi, etc. UNIT mode sets the maximum length of the displayed value in digits, plus 1, so that with UNIT 2, an entry of 65536 is shown as “64.0 Ki”. It is easy to then switch back to raw bytes or bits or whatever by changing to ALL mode.

• TODO: Ideas solicited!

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

License

This work is © 2025 by Warren Young and is licensed under CC BY-NC-SA 4.0

---

1. ^{^} …and SCI .1 is ignored. Yay!
2. ^{^} HP always had the best commas on their fixed-segment LCDs. 🤓 A low resolution dot matrix display like on an HP-28S or a DM15 cannot help but produce stubby, ugly tick marks for “commas,” whereas the R47’s high resolution display approaches the beauty of old HPs like the Voyagers and the HP-20S.
3. ^{^} It was exposed on the WP43 — one of R47’s predecessors — as 🟦 ENTER, but we lost that in all the reshuffling that resulted in the R47. One must now dig into the function CATalog to find its equivalent, DROP𝑥, making the option of drop-on-backspace more valuable on the R47 than on the WP43.