The Museum of HP Calculators

HP-15C Features

Features in optional ROMs are listed as Option.
Features in HP mag card or tape Application Pacs are listed as +.
Other software is not included.
Display and Keyboard HP-15C
Display type LCD
Display format 1 Line
FIXed number format Yes
SCIentific number format Yes
ENGineering number format Yes
STanDard / ALL number format -
Alpha messages and prompts -
Softkeys labeled by mag. card or overlay -
Softkeys labeled by display menus -
Softkeys with neither labeling system Yes
Status annunciators Yes
Redefinable keyboard -
Logic HP-15C
Logic system RPN
Stack levels 4
Last x Yes
Undo -
Precedence -
Parentheses -
Storage Addition (STO +) Yes
Storage Arithmetic (STO +, −, ×, ÷) Yes
Storage Exponentiation (STO ^) -
Recall Arithmetic Yes
Named variables -
Multiple data types -
Directories -
Math HP-15C
+, −, ×, ÷ Yes 
1/x Yes
x2 Yes
LOG x Yes
10x Yes
LN x Yes
ex Yes
yx Yes
π Yes
% Yes
% change Yes
INTeger truncation and ABSolute value Yes
Trigonometric functions (SIN, COS etc.) Yes
Hyperbolic trig. (SINH, COSH etc.) Yes
# of trig. modes (degrees, radians, grads) 3
Advanced Math HP-15C
Solver / root finder Yes
Numeric integration Yes
Complex numbers Yes
Matrix operations Yes
Matrix writer -
Equation writer -
Symbolic operations -
Fractions -
Plotting and graphics (display) -
Plotting and graphics (printer / plotter) -
Statistical HP-15C
Mean, standard deviation (# of variables) 2
Σ of n, x, x2 Yes
Σ of n, x, x2, y Yes
Σ of n, x, x2, y, xy Yes
Σ of n, x, x2, y, y2, xy Yes
Σ of lists -
Random number generator Yes
Linear regression, estimate  Yes
Curve fitting -
Correlation coefficient Yes
Normal distribution -
Factorial Yes
Gamma Yes
Combinations and permutations Yes
Scientific and Time HP-15C
Polar / rectangular conversions Yes
Base conversions (2, 8, 10, 16) -
Arithmetic in bases 2, 8 and 16 -
Bit operations (AND, OR, XOR, ...) -
Selectable word size (1-64 bits) -
Selectable complement mode (1's, 2's, unsigned) -
Decimal hrs / hrs.min.sec. conversions Yes
Hrs.min.sec arithmetic -
Time of day clock -
Timer -
Dynamic calculations (timer × rate) -
Alarms -
Unit Conversions HP-15C
Centimeters / inches -
Millimeters / inches -
Meters / feet -
Kilograms / pounds (mass) -
Newtons / pounds (force) -
British thermal units / joules -
Liters / gallons -
° Celsius / ° Fahrenheit -
Other -
User-defined units -
Time Value of Money HP-15C
Number of payments (n) -
Interest rate (i) -
Present Value (PV) -
Payment (PMT) -
Future Value (FV) -
Cash Flow Analysis HP-15C
Net present value (NPV) -
Internal rate of return (IRR) -
Amortization HP-15C
Accumulated Interest (ACC INT) -
Balance (BAL) -
Depreciation HP-15C
Straight line (SL) -
Sum of the years digits (SOYD) -
Declining balance (DB) -
Bonds and calendar functions HP-15C
Bond price -
Bond yield -
Date arithmetic / calendar functions -
Memory and Programming HP-15C
Programming language(s) RPN
RAM / Max # of variables or addressable registers 67
Max # of program steps 448*
RAM / Max vars or regs with full optional RAM -
Max # of prog steps with full optional RAM -
Merged program steps  Yes
Manual register / program memory allocation  Yes
Automatic register / program memory allocation -
Overlapped register and program memory -
Continuous memory Yes
Flags 10
Conditional tests 12
Subroutine levels 7
Indexed looping (increment by +/- 1, end at 0) Yes
Indexed looping (choice of increment and end) Yes
Multiple index / loop registers Loop only
Line number addressing Via I*
Branching by relative line number -
Global program label addressing Yes
Local program label addressing -
Indirect / computed addressing and control Yes
Multiple indirection registers -
Pause Yes
Alpha messages and prompts in programs -
Alpha program listings -
Alpha string manipulation -
Program step insert / delete Yes
I/O and Expansion Features HP-15C
ROM modules -
RAM modules or expansion option -
General expansion slots / connector -
Magnetic card reader/writer -
Tape drive -
Disk drive -
Upgradeable firmware -
Optical wand -
Serial port -
Infrared input -
Infrared output -
Printer -
Networking -
Other -
General HP-15C
Sounds -
Self test Yes
Hard case (in addition to soft case) -
Additional Features -
Batteries 3 SR44
Length (inches) 5.1"
Width 3.1"
Height 0.6"
Weight (oz or lbs) 4 oz
Year of introduction 1982
Features in optional ROMs are listed as Option.
Features in HP mag card or tape Application Pacs are listed as +.
Other software is not included.

Unlim means limited only by available memory.
HP-15C notes:
  • The HP-15C had enough memory for 448 one-byte instructions but some instructions required two bytes.
  • If the number in the I register was negative, the calculator branched to the line number indicated by the absolute value of that number.
  • Self test: with the calculator off, hold the × key down and press and release ON, then release ×. The calculator will display running for around half a minute and then activate the entire display to indicate success. The test may be done continuously by (with the calculator off) holding + down while pressing the ON key. To stop the continuous test at the end of the current iteration, press and hold − and then press ON.
  • There is also a keyboard test. With the calculator off, press and hold ÷ and press ON. Now press each key from the top left moving left to right and then down (the enter key gets pressed in both the third and fourth rows.) If all keys are pressed in the correct order and are working, the model number (without the C) is displayed. Otherwise, Error 9 is displayed. (The display will show a changing pattern of segments as keys are pressed.)

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