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
Directories	Yes
Math	HP-28S
+, −, ×, ÷	Yes
1/x	Yes
√	Yes
x²	Yes
LOG x	Yes
10^x	Yes
LN x	Yes
e^x	Yes
y^x	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)	2
Advanced Math	HP-28S
Solver / root finder	Yes
Numeric integration	Yes
Complex numbers	Yes
Matrix operations	Yes
Matrix writer	-
Equation writer	-
Symbolic operations	Yes
Fractions	-
Plotting and graphics (display)	Yes
Plotting and graphics (printer / plotter)	Option
Statistical	HP-28S
Mean, standard deviation (# of variables)	Multiple
Σ of n, x, x²	-
Σ of n, x, x², y	-
Σ of n, x, x², y, xy	-
Σ of n, x, x², y, y², xy	-
Σ of lists	Yes
Random number generator	Yes
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)	Yes
Selectable complement 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	-
Disk drive	-
Upgradeable firmware	-
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	-
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.

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

Directories

Yes

Math

HP-28S

+, −, ×, ÷

Yes

1/x

Yes

√

Yes

x²

Yes

LOG x

Yes

10^x

Yes

LN x

Yes

e^x

Yes

y^x

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)

Advanced Math

HP-28S

Solver / root finder

Yes

Numeric integration

Yes

Complex numbers

Yes

Matrix operations

Yes

Matrix writer

Equation writer

Symbolic operations

Yes

Fractions

Plotting and graphics (display)

Yes

Plotting and graphics (printer / plotter)

Option

Statistical

HP-28S

Mean, standard deviation (# of variables)

Multiple

Σ of n, x, x²

Σ of n, x, x², y

Σ of n, x, x², y, xy

Σ of n, x, x², y, y², xy

Σ of lists

Yes

Random number generator

Yes

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)

Yes

Selectable complement 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

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

Disk drive

Upgradeable firmware

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

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 continuous self test, with the calculator turned on, press and hold ON and press ◀. The calculator will step through a series of self-tests and will display OK-28S briefly at the end and then loop back to the beginning and repeat. Halt this test by pressing and holding ON and pressing the ▲ key.
To start the keyboard test, with the calculator turned on, press and hold ON and press the NEXT key. 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.

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