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Chapter 49

The HP 9810/20/30 Series

A New Series of Programmable Calculators1

Richard M. Spangler

In recent years, programmable calculators have taken on a large portion of the computation jobs that were previously handled by computers. Calculators have several advantages that are responsible for this trend. Calculators are small, self-contained, and easily transported-they can be brought directly to the user's desk. They are quiet, and fit easily into a laboratory or office environment. No complicated turn-on procedure is required; the user merely turns on the power switch, and the calculator is ready. The most important advantage is a psychological one-calculators are "friendly." They are interactive, they provide immediate feedback and immediate answers, and they are dedicated to their user.

The 9800 Series is a new line of powerful programmable calculators and an extensive set of calculator peripherals. The series is designed to cover a broad range of applications. Important objectives of the new series are to provide the user with a choice of calculators that are flexible and expandable, and to support those calculators with comprehensive applications software and peripherals.

The new 9800 Series is the successor of the 9100A/B [Hewlett-Packard, September 19681, HP's first programmable calculators. These earlier calculators were as powerful as the limits of technology at the time of their conception would allow them to be. But with technological advances come better calculators, hence the 9800 Series.

Three Models

There are currently three calculators in the 9800 Series. Model 10 is a key-per-function calculator with a keyboard and language that are extensions of the HP 9100A/B. The display is a three-register numeric display like the 9100A/B's, but uses seven-segment light-emitting-diode characters rather than a cathode-ray tube.

Model 20 has a statement-oriented algebraic language. The user doesn't have to position his variables in special registers or keep track of temporary results. He can enter arithmetic expressions in the same order as he would read them, including parentheses. Model 20 even allows implied multiplication, something that's not allowed even in most high-level computer languages. Model 20 has a display of 16 alphanumeric characters that can display a whole statement at a time. The alphanumeric display can be used during program execution to display comments and instructions as well as numeric results. This capability enhances the interactiveness of this model.

Model 30 is even more interactive. The keyboard is alphanumeric, like a typewriter, rather than key-per-function. This complements the 32-character alphanumeric display by making it convenient to enter text and messages. The programming language of the Model 30 is BASIC, a well-known and easy-to-learn computer language that is designed for use in interactive environments.

The electronics of the 9800 Series is general in design and is common to all three calculators. The central processing unit is a microprogrammed, 16 bit serial processor that implements a general computer machine language (see article, p. 000). The three separate keyboard languages and the arithmetic routines are implemented by firmware routines stored in MOS read-only memory (ROM), and the user's programs are stored in MOS read-write memory. The input/output structure is a general purpose system which makes it possible to interface with a wide variety of peripherals (see article, p. 817).

Many Peripherals

Some of the more important peripherals that have been interfaced are:


Card Reader
Output Typewriter
X-Y Plotter
Mechanical Paper Tape Reader
Magnetic Tape Cassette
Thermal Line Printer
Hopper Fed Card Reader
Instrumentation Coupler
Paper Tape Reader
Paper Tape Punch

Several general purpose interface cards are also available to interface with other HP instruments, the new HP interface systems [Nelson and Ricci, 1972], and many peripherals from other manufacturers.

Flexible and Expandable

Flexibility and expandability of the keyboard and programming languages of 9800 Series calculators are provided through the use of add-on ROM modules. From the optional ROMs available, the


1Hewlett-Packard Journal, vol. 24, December 1972, pp. 2-4.

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