Features in optional ROMs are listed as Option. 

Display and Keyboard  HP38C  HP12C 
Display type  LED  LCD 
Display format  1 Line  1 Line 
FIXed number format  Yes  Yes 
SCIentific number format  Yes  Yes* 
ENGineering number format     
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     
Status annunciators    Yes 
Redefinable keyboard     
Logic  HP38C  HP12C 
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     
Named variables     
Multiple data types     
Directories     
Math  HP38C  HP12C 
+, , ×, ÷  Yes  Yes 
1/x  Yes  Yes 
sq. root  Yes  Yes 
x^{2}     
LOG x     
10^{x}     
LN x  Yes  Yes 
e^{x}  Yes  Yes 
y^{x}  Yes  Yes 
pi     
%  Yes  Yes 
% change  Yes  Yes 
INTeger truncation and ABSolute value  Yes  INT only 
Trigonometric functions (SIN, COS etc.)     
Hyperbolic trig. (SINH, COSH etc.)     
# of trig. modes (degrees, radians, grads)     
Advanced Math  HP38C  HP12C 
Solver / root finder     
Numeric integration     
Complex numbers     
Matrix operations     
Matrix writer     
Equation writer     
Symbolic operations     
Fractions     
Plotting and graphics (display)     
Plotting and graphics (printer / plotter)     
Statistical  HP38C  HP12C 
Mean, standard deviation (# of variables)  2  2 
Summation of n, x, x^{2}  Yes  Yes 
Summation of n, x, x^{2}, y  Yes  Yes 
Summation of n, x, x^{2}, y, xy  Yes  Yes 
Summation of n, x, x^{2}, y, y^{2}, xy  Yes  Yes 
Summation of lists     
Random number generator     
Linear regression, estimate  Yes  Yes 
Curve fitting     
Correlation coefficient  Yes  Yes 
Normal distribution     
Factorial  Yes  Yes 
Gamma     
Combinations and permutations     
Scientific and Time  
Polar / rectangular conversions     
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     
Hrs.min.sec arithmetic     
Time of day clock     
Timer     
Dynamic calculations (timer × rate)     
Alarms     
Unit Conversions  
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  HP38C  HP12C 
Number of payments (n)  Yes  Yes 
Interest rate (i)  Yes  Yes 
Present Value (PV)  Yes  Yes 
Payment (PMT)  Yes  Yes 
Future Value (FV)  Yes  Yes 
Cash Flow Analysis  HP38C  HP12C 
Net present value (NPV)  Yes  Yes 
Internal rate of return (IRR)  Yes  Yes 
Amortization  HP38C  HP12C 
Accumulated Interest (ACC INT)  Yes  Yes 
Balance (BAL)  Yes  Yes 
Depreciation  HP38C  HP12C 
Straight line (SL)    Yes 
Sum of the years digits (SOYD)    Yes 
Declining balance (DB)    Yes 
Bonds and calendar functions  HP38C  HP12C 
Bond price    Yes 
Bond yield    Yes 
Date arithmetic / calendar functions    Yes 
Memory and Programming  HP38C  HP12C 
Programming language(s)  RPN  RPN 
RAM / Max # of variables or addressable registers  20  20 
Max # of program steps  99  99 
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     
Automatic register / program memory allocation  Yes 
Yes 
Overlapped register and program memory     
Continuous memory  Yes 
Yes 
Flags     
Conditional tests  2  2 
Subroutine levels     
Indexed looping (increment by +/ 1, end at 0)     
Indexed looping (choice of increment and end)     
Multiple index / loop registers     
Line number addressing    Yes 
Branching by relative line number     
Global program label addressing     
Local program label addressing     
Indirect / computed addressing and control     
Multiple indirection registers     
Pause  Yes  Yes 
Alpha messages and prompts in programs     
Alpha program listings     
Alpha string manipulation     
Program step insert / delete     
I/O and Expansion Features  HP38C  HP12C 
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  HP38C  HP12C 
Sounds     
Self test  Yes  Yes 
Hard case (in addition to soft case)     
Additional Features     
Batteries  Rechargeable  3 SR44 
Length (inches)  5.6"  5.1" 
Width  2.8"  3.1" 
Height  1.2"  0.6" 
Weight (oz or lbs)  68 oz*  4 oz 
Year of introduction  1979  1981 
Features in optional ROMs are listed as Option. 
HP38C notes:

HP12C notes:

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