Early HP calculators had numeric-only displays and when program lines were entered, they were displayed as numeric codes. On these models, (Since the 2021 update) the museum displays program listings that match the keys. When HP created their first alphanumeric handheld, the HP-41C, they designed it with a segmented LCD display that could display the alphabet and quite a few special characters, but not every character. Thus, while the calculator's display could show characters like *, ≠ and < it could not display, for example, ≤, ⇔ and √. As a result, many keyboard symbols were replaced by more than one "more-basic" symbol in the display, or the function was simply spelled out like SQRT. The later HP-42S had a dot-matrix display, but was meant to be software-compatible with the HP-41C so it continued many (but not all) of 41C's more-textual representations. (For example, the 42S uses ≤ and R↓ but continued to use E↑X instead of e^{x}.)
In addition to the above issues, many of our program listings have been submitted by people all around the world at different times, and people had their own symbologies, and in addition to all that, many readers will be reading a listing for one model with the intent of using it on another model. So, during the 2021 update, the curator has cleaned up and modernized many of the listings, and made many of the symbologies significantly more uniform than they once were but eventually gave up on displaying them all in a grand unified way. Early models are shown as the buttons you press. HP-41C programs are shown as they are displayed and later models, including the HP-42S, usually use a mix. Most of these differences are (hopefully) self-evident, but just in case, a decoder ring is shown below:
Typical Key |
Also Shown As: |
Meaning |
---|---|---|
x⇔y | x<>y | Swap x and y. |
x⇔ | x<> | Swap x and a register/variable. |
≤ ≥ | <= => | Less than or equal to. Greater than or equal to. |
x^{2} | X↑2 | x squared. |
x^{2} | SQ | x squared on RPL models. |
y^{x} | Y↑X | y to the xth power. |
y^{x} | ^ | y to the xth power on RPL models. |
e^{x} | E↑X | e to the xth power. |
e^{x} | EXP | e to the xth power on RPL models. |
10^{x} | 10↑X | 10 to the xth power. |
10^{x} | ALOG | 10 to the xth power on RPL models. |
√x | SQRT | Square root of x. |
× | * | Multiply |
÷ | / | Divide |
COS^{-1} | ACOS | Arccosine. ACOS is the key legend on the HP-42S and RPL models. |
SIN^{-1} | ASIN | Arcsine. ASIN is the key legend on the HP-42S and RPL models. |
TAN^{-1} | ATAN | Arctangent. ATAN is the key legend on the HP-42S and RPL models. |
R↓ | RDN | Roll the stack Down. (Do not confuse with RND!) |
R→P, D→R etc. |
R-P, D-R etc. |
Conversions have → on the key but may display as -. |
\ | varies | See below. |
Strings on the HP-41C are displayed like ᵀText and listed on a printer like "Text". The HP-42S displays quoted strings in both contexts. Museum listings use the quoted format.
Some pages use \ to indicate either that a multi-character string that follows is a single key (e.g.: \R/S is the R/S key or \+/- is the change sign key) or to indicate a special character that is not easily displayable. For example \LF indicates the visible Line Feed character on the HP-42S.
In addition to the above, as of this writing (June 1, 2021) many programs have still not been modernized. As a result, you will see that many people used additional "work-arounds" to express HP keys as simple ASCII, ISO 8859, Windows-125x, etc. The curator is still working on these. 6 months ago, I expected to get these done in the summer, and I expected to still be un-vaccinated and mostly staying home. However, vaccinations happened way sooner than I expected and so my summer has become much less predictable. So, for now, here is your decoder ring for these:
Original ASCII Style | New UTF8 style | Meaning |
---|---|---|
-> or \-> | → | Used wherever a calculator would use a right arrow key such as conversions. |
/ or : | ÷ or / | Division. / is typically still used in formulas. |
^ | ↑ or superscript | Used both to represent upward arrows (like R^ for R↑) and for exponentiation (like 2^3 for 2^{3}). Of course, the latter is kept for programs in BASIC. |
|- or \|- | ⊢ | The alpha append symbol on the 41C/42S. On the HP-41C, press Shift K right after entering Alpha mode. On the 42S, press Enter right after entering Alpha mode. |
delta | Δ | Change in. Typically followed by %, days, x... |
integrate | ∫ | Integration |
mean x | x̄ | Mean of x values |
est. y | ŷ | Estimate of y value |
pi | π | The constant 3.14159... |
Roll dn, down, Rv etc. | R↓ | Roll the stack down |
Roll up, up, R^ etc. | R↑ | Roll the stack up |
sqrt | √ or √x | Square root |
sum | Σ | Summation |
sum+ | Σ+ | Sum add |
sum- | Σ− | Sum subtract |
x!=y, x/=y, x<>y? x#y, x ne y etc. | x≠y | x not equal to y test. (This one is tricky because a few people contributed programs with <> as not equal and others as swap. Fortunately the not equal case is typically followed by a "?".) |
x<>y, x<->y, swap etc. | x⇔y, x⇄y | Exchange x and y. x⇄y is used on early desktop models. |
x<>I | x⇔I, or x<>I | Exchange x and I. See above. |
<< >> or \<< \>> | « » | Object delimiters used on RPL models. |
left shift right shift or \ls \rs | ↰ ↱ | Left and Right Shift keys. |
\lf | \lf | This is the visible line feed character used on the HP-42S. It is entered only via the alpha menu. There appears to be no obvious Unicode code point for such a specialized character so this one will probably remain as-is. (Unicode does allow totally custom characters but the curator assumes using them will flummox readers who need to use screen readers.) |
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