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  HP11C  HP15C 
Display type  LCD  LCD 
Display format  1 Line  1 Line 
FIXed number format  Yes  Yes 
SCIentific number format  Yes  Yes 
ENGineering number format  Yes  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  Yes 
Status annunciators  Yes  Yes 
Redefinable keyboard     
Logic  HP11C  HP15C 
Logic system  RPN  RPN 
Stack levels  4  4 
Last x  Yes  Yes 
Undo     
Precedence     
Parentheses     
Storage Addition (STO +)  Yes  Yes 
Storage Arithmetic (STO +, −, ×, ÷)  Yes  Yes 
Storage Exponentiation (STO ^)     
Recall Arithmetic    Yes 
Named variables     
Multiple data types     
Directories     
Math  HP11C  HP15C 
+, −, ×, ÷  Yes  Yes 
1/x  Yes  Yes 
√  Yes  Yes 
x^{2}  Yes  Yes 
LOG x  Yes  Yes 
10^{x}  Yes  Yes 
LN x  Yes  Yes 
e^{x}  Yes  Yes 
y^{x}  Yes  Yes 
π  Yes  Yes 
%  Yes  Yes 
% change  Yes  Yes 
INTeger truncation and ABSolute value  Yes  Yes 
Trigonometric functions (SIN, COS etc.)  Yes  Yes 
Hyperbolic trig. (SINH, COSH etc.)  Yes  Yes 
# of trig. modes (degrees, radians, grads)  3  3 
Advanced Math  HP11C  HP15C 
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  HP11C  HP15C 
Mean, standard deviation (# of variables)  2  2 
Σ of n, x, x^{2}  Yes  Yes 
Σ of n, x, x^{2}, y  Yes  Yes 
Σ of n, x, x^{2}, y, xy  Yes  Yes 
Σ of n, x, x^{2}, y, y^{2}, xy  Yes  Yes 
Σ of lists     
Random number generator  Yes  Yes 
Linear regression, estimate  Yes  Yes 
Curve fitting     
Correlation coefficient  Yes  Yes 
Normal distribution     
Factorial  Yes  Yes 
Gamma  Yes  Yes 
Combinations and permutations  Yes  Yes 
Scientific and Time  HP11C  HP15C 
Polar / rectangular conversions  Yes  Yes 
Base conversions (2, 8, 10, 16)     
Arithmetic in bases 2, 8 and 16     
Bit operations (AND, OR, XOR, ...)     
Selectable word size (164 bits)     
Selectable complement mode (1's, 2's, unsigned)     
Decimal hrs / hrs.min.sec. conversions  Yes  Yes 
Hrs.min.sec arithmetic     
Time of day clock     
Timer     
Dynamic calculations (timer × rate)     
Alarms     
Unit Conversions  HP11C  HP15C 
Centimeters / inches     
Millimeters / inches     
Meters / feet     
Kilograms / pounds (mass)     
Newtons / pounds (force)     
British thermal units / joules     
Liters / gallons     
° Celsius / ° Fahrenheit     
Other     
Userdefined units     
Time Value of Money  HP11C  HP15C 
Number of payments (n)     
Interest rate (i)     
Present Value (PV)     
Payment (PMT)     
Future Value (FV)     
Cash Flow Analysis  HP11C  HP15C 
Net present value (NPV)     
Internal rate of return (IRR)     
Amortization  HP11C  HP15C 
Accumulated Interest (ACC INT)     
Balance (BAL)     
Depreciation  HP11C  HP15C 
Straight line (SL)     
Sum of the years digits (SOYD)     
Declining balance (DB)     
Bonds and calendar functions  HP11C  HP15C 
Bond price     
Bond yield     
Date arithmetic / calendar functions     
Memory and Programming  HP11C  HP15C 
Programming language(s)  RPN  RPN 
RAM / Max # of variables or addressable registers  21  67 
Max # of program steps  203  448* 
RAM / Max vars or regs with full optional RAM     
Max # of prog steps with full optional RAM     
Merged program steps  Yes  Yes 
Manual register / program memory allocation    Yes 
Automatic register / program memory allocation  Yes   
Overlapped register and program memory     
Continuous memory  Yes  Yes 
Flags  2  10 
Conditional tests  8  12 
Subroutine levels  4  7 
Indexed looping (increment by +/ 1, end at 0)  Yes  Yes 
Indexed looping (choice of increment and end)  Yes  Yes 
Multiple index / loop registers    Loop only 
Line number addressing    Via I* 
Branching by relative line number     
Global program label addressing  Yes  Yes 
Local program label addressing     
Indirect / computed addressing and control  Yes  Yes 
Multiple indirection registers     
Pause  Yes  Yes 
Alpha messages and prompts in programs     
Alpha program listings     
Alpha string manipulation     
Program step insert / delete  Yes  Yes 
I/O and Expansion Features  HP11C  HP15C 
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  HP11C  HP15C 
Sounds     
Self test  Yes  Yes 
Hard case (in addition to soft case)     
Additional Features     
Batteries  3 SR44  3 SR44 
Length (inches)  5.1"  5.1" 
Width  3.1"  3.1" 
Height  0.6"  0.6" 
Weight (oz or lbs)  4 oz  4 oz 
Year of introduction  1981  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. 
HP11C notes:

HP15C notes:

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