HP 35s

HP-35s

Front view of the HP-35s
Type	Programmable Scientific
Manufacturer	Hewlett-Packard
Introduced	2007
Design firm	Kinpo Electronics, Inc
Calculator
Entry mode	RPN, Infix
Precision	15 digits ±499 exponent (internal)
Display Type	LCD Dot-matrix
Display Size	2 × 14 Character
CPU
Processor	Sunplus Technology 8502
Programming
Programming language(s)	RPN Keystroke (fully merged, Turing complete)
User Memory	30KB
Memory Register	26 .. 800
Other
Power supply	2 × CR2032 batteries
Weight	125 g (4.4 oz)
Dimensions	15.8 × 8.2 × 1.82 cm (6.22 × 3.23 × 0.72 in)

The HP 35s Scientific Calculator is, as of 2007, the latest in Hewlett-Packard's long line of non-graphing scientific and programmable calculators. Although it is a successor to the HP 33s, it was introduced to commemorate the 35th anniversary of the HP-35, Hewlett-Packard's first pocket calculator (and the world's first pocket scientific calculator).

The HP 35s uses either Reverse Polish Notation (RPN) or Infix notation as input.

Other features of the HP 35s include:

• Two-line alphanumeric LCD display
• 26 memory registers
• Scientific and statistical functions
• Operation in decimal, binary, octal, hexadecimal
• Equation solver with arbitrary variable isolation (first seen on the HP-18C)
• Numerical integration (first seen on the HP-34C)
• Support for input and display of fractions
• Complex number and vector calculations
• Unit conversions and table of physical constants
• Approximately 30 kilobytes of memory for programs and/or data

Although the HP 35s has far more functions, processing power, and memory than the original HP-35 which it commemorates, Hewlett-Packard has attempted to give the HP 35s the look of the original HP-35 and other HP calculators of that era. It also features the sloped-front keys for which HP calculators (although not the original HP-35) are well known.

The physical appearance and keyboard layout of the HP 35s is very different than that of its immediate predecessor, the HP 33s, but the two calculators are functionally almost identical. The primary differences are:

• The HP 35s allows both label and line number addressing in programs. The HP 33s had only label addressing. With only 26 labels, it was difficult to write programs making use of the entire 30KB of memory.
• The memory in the HP 35s is also usable for data storage, in the form of up to 801 numbered memory registers.
• Support for vector operations is new in the HP 35s.
• Indirect branching, which allows the contents of a memory register to be used as the target of a branching instruction (GTO or XEQ) is available in the HP 33s, but was omitted from the HP 35s.^{[citation needed]}

Design and manufacture

The HP 35s was designed by Hewlett-Packard in conjunction with Kinpo Electronics, Inc. The latter company manufactures this calculator for HP.

Reception

The 35s has been welcomed by reviewers as a return to the best HP professional calculator traditions, in contrast to their more recent advanced calculators which were seen as feature-packed and heavily styled for the student market, but in some cases poorly designed and built. Particular mention has been made of the solid construction and the traditional HP feel of the keyboard with a big Enter key back in its traditional place. Shortcomings which have been identified include the lack of any facility for communication with a computer and the restrictive single-letter naming of programs and variables. Several firmware bugs have also been reported, which are not known to have been fixed as of 2011.

Programming

Unlike the original HP-35, the HP 35s is keystroke programmable, meaning that it can remember and later execute sequences of keystrokes to solve particular problems of interest to the user. These keystroke programs, in addition to performing any operation normally available on the keyboard, can also make use of conditional and unconditional branching and looping instructions, allowing programs to perform repetitive operations and make decisions.

Even with indirect jumping removed, the HP 35s still supports indirect addressing, with which it is still possible to implement a Universal Turing machine; and therefore the programming model of the HP 35s can be considered Turing complete.

As in normal operation, programming can be done in either in RPN or in D.A.L.

RPN mode programs are usually smaller and faster, while D.A.L. is better suited for interactive use and easier to use for those who are not used to RPN.

Programming example

Here is a sample program that computes the factorial of an integer number from 2 to 69. There are two versions of the example: one for algebraic mode (LBL A) and one for RPN mode (LBL R). Even in this small example the algebraic version is 14 bytes (56%) larger.

Algebraic version

(entered while in algebraic mode)

Step	Instruction	Comment
A001	LBLA	Start of program A
A002	ALG	Switch to algebraic mode
A003	LASTXSTON↵ Enter	Store displayed value in N
A004	1STOF↵ Enter	Store 1 in F
A005	RCLN×RCLFSTOF	Store N*F in F
A006	DSEN	Decrement N and if not zero ...
A007	GTOA005	... go back to step A005
A008	RTN	End of program - result is displayed
		Summary: LN=39

RPN version

(entered while in RPN mode)

Step	Instruction	Comment
R001	LBLR	Start of program R
R002	RPN	Switch to RPN mode
R003	STOI	Store x (stack) into I (memory)
R004	1	Start with 1
R005	RCL×I	Recall I (memory) and multiply with x (stack)
R006	DSEI	Decrement I and if not zero ...
R007	GTOR005	... go back to step R005
R008	RTN	End of program - result is in x (stack)
		Summary: LN=25

External links

• HP 35s Specifications
• HP 35s Datasheet (PDF)
• HP 35s Simulator for Windows