John Wolff's Web Museum

Hewlett-Packard Calculators

This page gives a brief description of some of the early Hewlett-Packard electronic calculators that have come my way from sources within Australia.

Detailed technical and historical information on the full range of Hewlett-Packard machines is available on-line at The Museum of HP Calculators.

HP9100B.jpg (6kb) Hewlett-Packard Model 9100B, S/N 0938A03791
Functions: Scientific, special functions, 32 memory registers
Programming: All keystrokes, subroutines, 392 steps, magnetic card storage
Technology: Discrete diode-resistor logic, magnetic core memory
Display: 10 significant digits, 2 exponent, 3-register CRT display
Dimensions: 16"W x 19"D x 8-1/2"H, weight 40 pounds
Manufactured: USA, October 1969

The Model 9100 was Hewlett-Packard's first calculator, introduced in mid-1968. It combined a full range of scientific functions with an extensive programming capability, including a magnetic card system for storage of programs and data. The machine was built entirely with discrete transistors, diode-resistor logic, and magnetic core memory - there are no integrated circuits.

This remarkable calculator was at least five years ahead of its time, and served as the benchmark against which all others were judged. Its price of just under US$5000 was four times the price of a top-line mechanical calculator, twice the price of most electronic machines, and more than a year's wages for many people at that time.

The illustration shows the "B" version, with increased memory capacity. This machine originally belonged to the State Electricity Commission of Victoria, where it was used for power system calculations in the engineering departments.

HP9810.jpg (8kb) Hewlett-Packard Model 9810, S/N 1228A04915
Functions: Scientific, plug-in option ROMs, 51 memory registers
Programming: All keystrokes, subroutines, 500 steps, magnetic card storage
Technology: MOS LSI, semiconductor ROM and RAM memory
Display: 10 significant digits, 3-register LED display, internal printer
Dimensions: 17-3/4"W x 21"D x 5-1/2"H, weight 34 pounds
Manufactured: USA, July 1972

HP's second-generation desktop calculators included three quite different models. The 9810 was basically an "upgrade" of the 9100, the 9820 used an algebraic keyboard language, and the 9830 was programmable in BASIC. Internally, however, the three machines were very similar. All were based on a 16-bit serial "mini-computer", built with MOS-LSI technology and semiconductor memory. The personalities of the different models were determined by the internal micro-programming, and by changes to the keyboard and display.

The 9810 had a 3-register display similar to the 9100, but using LED displays instead of the CRT, and it had an (optional) internal printer. The basic machine did not include the full complement of scientific functions, but relied on (optional) plug-in ROM modules to provide a choice of mathematical, statistical, or other functions. An auxilliary keypad with interchangeable overlays provided the user interface to the additional routines in the ROM modules.

This particular machine served for many years as the "office calculator" for a firm of surveyors in Melbourne, Australia. It came to me with the printer and mathematical ROMs, the original manuals and dust cover, and a documented library of survey calculations on magnetic cards, prepared by the original owners.

HP354567.jpg (6kb) First-generation HP Pocket Calculators
Model 35, 1972
Model 45, 1973
Model 67, 1975, programmable, magnetic card storage


HP212529.jpg (6kb) Second-generation HP Pocket Calculators
Model 21, 1975
Model 25, 1975, programmable
Model 29C, 1975, programmable, "continuous memory"

HP19C.jpg (9kb) Hewlett-Packard Model 19C, S/N 1802S12751
Functions: "Pocket" size, scientific, printing
Programming: Keystroke programming, continuous memory
Technology: MOS LSI
Display: 13 digit LED display, internal printer
Dimensions: 3-1/2"W x 6-1/2"D x 1-1/2"H, weight 12oz (incl batteries)
Manufactured: USA, January 1978

The HP Model 19C is a programmable scientific calculator with an in-built miniature thermal printer. The calculator is functionally equivalent to the second-generation Model 29C (above), but has been re-packaged into an older-style case to accommodate the printer and a 4-cell battery pack.

The printer will record the numerical display, the registers and stack, or the full program listing on its tiny (1-1/2" wide) paper roll.

Original text and images Copyright (C) John Wolff 2003.
Use at own risk; beware of errors; suggestions for improvement welcome.
Last Updated: 26 June 2003

Back to:    Home    Calculating Machines