>> What is qualitative difference between these two.  I had a 41cx for a
>> short while, but it got stolen from me.  I am currently looking at
>> both, and would like to know what the real differences are (like, does
>> the 28s have a timer?)

The major advantage of the HP-41 is that it is a flexible,
customizable calculator with I/O capabilities.  The HP-28S has no
customization other than typing in programs via the keyboard and no
I/O other than the I/R printer.

The major advantage of the HP-28 is that it is a state of the art
calculator with the memory and speed that is expected of a modern top
end hand held.  The HP-41 is an obsolete architecture that can only
support a limited amount of memory and is very slow.

The following is a copy of the comparison of the HP-28S and the HP-41
>from the HP sales glossy.

PHYSICAL FEATURES
  Display Type		Dot matrix		16 segment
  Display Size		4 lines of 23 chars	1 line 12 chars
  Keyboard		Numbers and letters	Numbers and letters

OPERATING FEATURES
  Built in functions	Over 1500		CX 200, CV 128
  Operating logic	RPN or algebraic	RPN

CONFIGURATION
  Peripherals		I/R printer		Too many to fit here
  Plug in modules	None			ROM, RAM, I/O
  Built in memory	32k bytes		3133 bytes
  Maximum memory	32k bytes		6433 bytes
  Clock			Software		CX or time module
  Alarms		No			CX or time module
  Text editor		Yes			CX or Ext functions
  Software		6 solutions books	27 books, 20 ROMs
  Redefinable keys	6			All

MATHS FEATURES
  Basic maths		Built in		Built in
  Graphics		Display/Printer		Printer
  Symbolic algebra	Built in		No
  Numeric integration	Built in		Maths/Stats or Adv Pac
  Symb poly integ	Built in		No
  Symbolic derivatives	Built in		No

SCIENTIFIC FEATURES
  Base conversions	Built in		Adv Pac
  Bit/Boolean		Built in		Adv Pac
  Complex numbers	Built in		Maths/Stats or Adv Pac
  Root finder		Built in		Maths/Stats or Adv Pac
  Hyperbolics		Built in		Maths/Stats Pac
  Matrices		Built in		Maths/Stats or Adv Pac
  Trigonometry		Built in		Built in
  Unit Conversions	Built in		Software

FINANCIAL FEATURES
  Time value of money	No			Adv or Finance Pac

STATISTICAL FEATURES
  Type			List based		Cumulative
  Scatter plots		Built in		No
  Std dev, Mean		Built in		Built in
  Linear regression	Built in		Maths/Stats Pac
  Correlation coeff.	Built in		Maths/Stats Pac
  Curve Fitting		No			Maths/Stats Pac
  Weighted Mean		No			Maths/Stats Pac
  Groups std dev	No			Maths/Stats Pac
  Probability analysis	Built in		Maths/Stats Pac
  Combinations/Perms	Built in		Maths/Stats Pac

PROGRAMMING
  Number of steps	Memory limited		Memory limited
  Custom applics	Yes			Yes
  Alpha strings		Yes			Yes
  Tests/flags		22/64			20/56
  Indexed looping	Yes			Yes
  Program labels	Memory limited		Memory limited
  Subroutine levels	Memory limited		6

DIMENSIONS
  Operating		7.5"x6.25"x0.5"		3.1"x5.6"x1.3"
  Non-operating		3.6"x6.5"x1.6"		3.1"x5.6"x1.3"
  Weight		8oz			7.2oz

POWER
  Operating current     8mA			20mA
  Non-operating current 1mA			2mA
  Off current		25uA			50uA
  Supply		3 N cells		4 N cells
  Typical life		9 months		6 months

VARIABLE STORAGE
  Real no range		10E-499 to 10E+499	10E-99 to 10E+99
  Real no precision	15 digits		12 digits
  Display precision	12 digits		12 digits
  Integer precision	64 bits			Not available


The features of the HP-41CX with either the Advantage Pac or the
Maths/Stats Pac are very similar to those of the HP-28S.  The main
things that the HP-28S does that cannot be done on the HP-41 are those
based around symbolic algebra.  The main things that the HP-41 does
that the HP-28S cannot do are based on the timer and on I/O.

Another thing to take into account is the size and shape of the two.
The HP-28S is a book format that opens for use.  As such it is harder
to use held in the hand.  The HP-41 is a traditional format calculator
designed so that it can be used away from a desk.

The final point is to do with futures.  HP has already announced the
obsolescence of the HP-41.  If you do get another HP-41, then do so
soon and buy any software or peripherals you need at the same time.
HP has announced that a new top end calculator will be launched some
time this year.  If you can wait, that is the one to go for.  If not,
I don't know how long the HP-28S will last after the new machine is
introduced.

Mark Simms

----------------------------------------------------------------------
Please note that I have no connection with Hewlett-Packard's
calculator operations other than as a user of their products.
----------------------------------------------------------------------
Opinions expressed are my own and are not intended to be an official
statement by Hewlett-Packard Company
----------------------------------------------------------------------
Name:         Mark Simms
Position:     Software Development Engineer
Organization: Hewlett-Packard Computer Peripherals Division
Email US:     mark%hpcpbla@hplb.hpl.hp.com
      UK:     mark%hpcpbla@hplb.hp.co.uk
Address:      Filton Road, Bristol BS12 6QZ, United Kingdom
----------------------------------------------------------------------