The Museum of HP Calculators

HP-28S 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-28S

Display type LCD

Display format 4Line

FIXed number format Yes

SCIentific number format Yes

ENGineering number format Yes

STanDard / ALL number format Yes

Alpha messages and prompts Yes

Softkeys labeled by mag. card or overlay -

Softkeys labeled by display menus Yes

Softkeys with neither labeling system -

Status annunciators Yes

Redefinable keyboard -

Logic HP-28S

Logic system RPN/RPL

Stack levels Unlim

Last x Yes

Undo Yes

Precedence Yes

Parentheses Yes

Storage Addition (STO +) Yes

Storage Arithmetic (STO +, -, ×, ÷) Yes

Storage Exponentiation (STO ^) -

Recall Arithmetic -

Named variables Yes

Multiple data types Yes

Math HP-28S

+, -, ×, ÷ Yes

1/x Yes

sq. root Yes

x² Yes

LOG x Yes

10^x Yes

LN x Yes

e^x Yes

y^x Yes

pi Yes

% Yes

% change Yes

INTeger truncation and ABSolute value -

Trigonometric functions (SIN, COS etc.) Yes

Hyperbolic trig. (SINH, COSH etc.) Yes

# of trig. modes (degrees, radians, grads) 2

Advanced Math HP-28S

Solver / root finder Yes

Numeric integration Yes

Complex numbers Yes

Matrix operations Yes

Symbolic operations Yes

Fractions -

Plotting and graphics (display) Yes

Plotting and graphics (printer / plotter) Option

Statistical HP-28S

Mean, standard deviation (# of variables) Multiple

Summation of n, x, x² -

Summation of n, x, x², y -

Summation of n, x, x², y, xy -

Summation of n, x, x², y, y², xy -

Summation of lists Yes

Random number generator -

Linear regression, estimate Yes

Curve fitting -

Correlation coefficient Yes

Normal distribution Yes

Factorial Yes

Gamma Yes

Combinations and permutations Yes

Scientific and Time
HP-28S

Polar / rectangular conversions Yes

Base conversions (2, 8, 10, 16) Yes

Arithmetic in bases 2, 8 and 16 Yes

Bit operations (AND, OR, XOR, ...) Yes

Selectable word size (1-64 bits) -

Selectable compliment mode (1's, 2's, unsigned) -

Decimal hrs / hrs.min.sec. conversions Yes

Hrs.min.sec arithmetic Yes

Time of day clock -

Timer -

Dynamic calculations (timer × rate) -

Alarms -

Unit Conversions
HP-28S

Centimeters / inches Yes

Millimeters / inches Yes

Meters / feet Yes

Kilograms / pounds (mass) Yes

Newtons / pounds (force) Yes

British thermal units / joules Yes

Liters / gallons Yes

° Celsius / ° Fahrenheit Yes

Other Yes

User-defined units Yes

Time Value of Money HP-28S

Number of payments (n) -

Interest rate (i) -

Present Value (PV) -

Payment (PMT) -

Future Value (FV) -

Cash Flow Analysis HP-28S

Net present value (NPV) -

Internal rate of return (IRR) -

Amortization HP-28S

Accumulated Interest (ACC INT) -

Balance (BAL) -

Depreciation HP-28S

Straight line (SL) -

Sum of the years digits (SOYD) -

Declining balance (DB) -

Bonds and calendar functions HP-28S

Bond price -

Bond yield -

Date arithmetic / calendar functions -

Memory and Programming HP-28S

Programming language(s) RPL

RAM / Max # of variables or addressable registers 32K Bytes

Max # of program steps Unlim

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 -

Automatic register / program memory allocation
Yes

Overlapped register and program memory -

Continuous memory
Yes

Flags 64

Conditional tests Many

Subroutine levels Unlim

Indexed looping (increment by +/- 1, end at 0) Yes

Indexed looping (choice of increment and end) Yes

Multiple index / loop registers Yes

Line number addressing -

Branching by relative line number -

Global program label addressing Yes

Local program label addressing Yes

Indirect / computed addressing and control Yes

Multiple indirection registers Yes

Pause Yes

Alpha messages and prompts in programs Yes

Alpha program listings Option

Alpha string manipulation Yes

Program step insert / delete Yes

I/O and Expansion Features HP-28S

ROM modules -

RAM modules or expansion option -

General expansion slots / connector -

Magnetic card reader/writer -

Tape drive -

Optical wand -

Serial port -

Infrared input -

Infrared output Yes

Printer Option

Networking -

Other -

General HP-28S

Sounds Yes

Self test Yes

Hard case (in addition to soft case) -

Additional Features Directories

Batteries 3 N cells

Length (inches) 6.2"

Width 3.75"

Height 0.7"

Weight (oz or lbs) 8oz

Year of introduction 1987

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-28S notes:

To start the self test, press and hold ON and press the down arrow. The calculator will beep and display a series of vertical bars. You can now press any key to step through a series of tests (each with a different display - one blank.) Once the calculator displays KEYBOARD TEST, you must press each key on the alpha (left) keyboard starting from the upper left and proceeding from left to right and then down. You will hear a beep on each keystroke. After the alpha keyboard, do the same with the main (right) keyboard. When you are finished, you will see: OK-28S. The message FAIL will be displayed if there is a problem or if you press keys in the wrong order. By pressing and holding ON and pressing the left arrow, you can put the calculator into a continuous self-test (minus the keyboard test.) To exit the continuous test press and hold ON and press the up arrow key.

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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-28S
Display type	LCD
Display format	4Line
FIXed number format	Yes
SCIentific number format	Yes
ENGineering number format	Yes
STanDard / ALL number format	Yes
Alpha messages and prompts	Yes
Softkeys labeled by mag. card or overlay	-
Softkeys labeled by display menus	Yes
Softkeys with neither labeling system	-
Status annunciators	Yes
Redefinable keyboard	-

Logic	HP-28S
Logic system	RPN/RPL
Stack levels	Unlim
Last x	Yes
Undo	Yes
Precedence	Yes
Parentheses	Yes
Storage Addition (STO +)	Yes
Storage Arithmetic (STO +, -, ×, ÷)	Yes
Storage Exponentiation (STO ^)	-
Recall Arithmetic	-
Named variables	Yes
Multiple data types	Yes

Math	HP-28S
+, -, ×, ÷	Yes
1/x	Yes
sq. root	Yes
x²	Yes
LOG x	Yes
10^x	Yes
LN x	Yes
e^x	Yes
y^x	Yes
pi	Yes
%	Yes
% change	Yes
INTeger truncation and ABSolute value	-
Trigonometric functions (SIN, COS etc.)	Yes
Hyperbolic trig. (SINH, COSH etc.)	Yes
# of trig. modes (degrees, radians, grads)	2

Advanced Math	HP-28S
Solver / root finder	Yes
Numeric integration	Yes
Complex numbers	Yes
Matrix operations	Yes
Symbolic operations	Yes
Fractions	-
Plotting and graphics (display)	Yes
Plotting and graphics (printer / plotter)	Option

Statistical	HP-28S
Mean, standard deviation (# of variables)	Multiple
Summation of n, x, x²	-
Summation of n, x, x², y	-
Summation of n, x, x², y, xy	-
Summation of n, x, x², y, y², xy	-
Summation of lists	Yes
Random number generator	-
Linear regression, estimate	Yes
Curve fitting	-
Correlation coefficient	Yes
Normal distribution	Yes
Factorial	Yes
Gamma	Yes
Combinations and permutations	Yes

Scientific and Time	HP-28S
Polar / rectangular conversions	Yes
Base conversions (2, 8, 10, 16)	Yes
Arithmetic in bases 2, 8 and 16	Yes
Bit operations (AND, OR, XOR, ...)	Yes
Selectable word size (1-64 bits)	-
Selectable compliment mode (1's, 2's, unsigned)	-
Decimal hrs / hrs.min.sec. conversions	Yes
Hrs.min.sec arithmetic	Yes
Time of day clock	-
Timer	-
Dynamic calculations (timer × rate)	-
Alarms	-

Unit Conversions	HP-28S
Centimeters / inches	Yes
Millimeters / inches	Yes
Meters / feet	Yes
Kilograms / pounds (mass)	Yes
Newtons / pounds (force)	Yes
British thermal units / joules	Yes
Liters / gallons	Yes
° Celsius / ° Fahrenheit	Yes
Other	Yes
User-defined units	Yes

Time Value of Money	HP-28S
Number of payments (n)	-
Interest rate (i)	-
Present Value (PV)	-
Payment (PMT)	-
Future Value (FV)	-

Cash Flow Analysis	HP-28S
Net present value (NPV)	-
Internal rate of return (IRR)	-

Amortization	HP-28S
Accumulated Interest (ACC INT)	-
Balance (BAL)	-

Depreciation	HP-28S
Straight line (SL)	-
Sum of the years digits (SOYD)	-
Declining balance (DB)	-

Bonds and calendar functions	HP-28S
Bond price	-
Bond yield	-
Date arithmetic / calendar functions	-

Memory and Programming	HP-28S
Programming language(s)	RPL
RAM / Max # of variables or addressable registers	32K Bytes
Max # of program steps	Unlim
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	-
Automatic register / program memory allocation	Yes
Overlapped register and program memory	-
Continuous memory	Yes
Flags	64
Conditional tests	Many
Subroutine levels	Unlim
Indexed looping (increment by +/- 1, end at 0)	Yes
Indexed looping (choice of increment and end)	Yes
Multiple index / loop registers	Yes
Line number addressing	-
Branching by relative line number	-
Global program label addressing	Yes
Local program label addressing	Yes
Indirect / computed addressing and control	Yes
Multiple indirection registers	Yes
Pause	Yes
Alpha messages and prompts in programs	Yes
Alpha program listings	Option
Alpha string manipulation	Yes
Program step insert / delete	Yes

I/O and Expansion Features	HP-28S
ROM modules	-
RAM modules or expansion option	-
General expansion slots / connector	-
Magnetic card reader/writer	-
Tape drive	-
Optical wand	-
Serial port	-
Infrared input	-
Infrared output	Yes
Printer	Option
Networking	-
Other	-

General	HP-28S
Sounds	Yes
Self test	Yes
Hard case (in addition to soft case)	-
Additional Features	Directories
Batteries	3 N cells
Length (inches)	6.2"
Width	3.75"
Height	0.7"
Weight (oz or lbs)	8oz
Year of introduction	1987
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.