HP 35s
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 Reverse Polish Notation (RPN) for input, although it is also capable of accepting input in a pure algebraic form. 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.
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 (a feature first seen on the HP-34C)
- Numerical integration (also 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 approximately 800 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.
The HP 35s was designed by Hewlett-Packard in conjunction with Kinpo Electronics, Inc. The latter company manufactures this calculator for HP.