HP-9810A Calculator

General description

The HP 9810A, released in 1971, was a pioneering programmable desktop calculator that marked a significant advancement in the field of computing. Developed by Hewlett-Packard as part of its esteemed 9800 series, this calculator was targeted towards professionals, engineers, scientists, and academics who required sophisticated computational capabilities.

At its core, the HP 9810A was built around the concept of programmability, which was a groundbreaking feature at the time. This allowed users to create and store sequences of calculations, enabling the calculator to perform complex tasks automatically. This was a significant departure from earlier calculators, which were limited to performing only basic arithmetic operations.

One of the distinctive features of the HP 9810A was its utilization of Reverse Polish Notation (RPN) for data entry and calculation. RPN, also known as postfix notation, streamlines mathematical operations by eliminating the need for parentheses and reducing the number of keystrokes required for complex calculations. While initially challenging for some users to grasp, RPN ultimately provided a more efficient and intuitive approach to calculation.

The calculator boasted a comprehensive set of built-in mathematical and scientific functions, encompassing arithmetic operations, trigonometric functions, logarithms, exponentiation, and more. These functions were essential for professionals engaged in various fields, including engineering, physics, mathematics, and finance.

What set the HP 9810A apart was its ability to store and execute user-programmed instructions. Programs could be written directly on the calculator using a specialized programming language, which included conditional statements, loops, and subroutines. This capability transformed the calculator from a mere computational tool into a versatile computing device, capable of performing custom calculations tailored to specific needs.

Furthermore, the HP 9810A featured a compact yet functional display that provided clear feedback to the user. This display not only presented numerical results but also conveyed programming prompts and error messages, enhancing the overall user experience.

The calculator’s memory capacity could be expanded using optional memory modules, allowing users to store additional programs and data. Additionally, HP offered a range of peripheral devices and accessories to extend the functionality of the calculator, such as printers, card readers, and interface modules.

The HP 9810A played a pivotal role in the evolution of computing technology, serving as a precursor to more advanced programmable calculators and eventually personal computers. Its impact on various industries, including engineering, science, and education, cannot be overstated. Even today, the HP 9810A remains a revered artifact among collectors and enthusiasts, symbolizing a significant milestone in the history of computing.

The most important individual characteristics of the 9810A are:

  • A three-register (x, y, and z) light-emitting diode display
  • Separate memories for program and data storage
  • All-decimal addressing of program and data storage
  • Modular internal expansion of program and/or data storage
  • Indirect addressing for any register reference
  • Arithmetic operations (all four functions) into or from all data registers
  • Optional function blocks (ROM) to define the operation of the lefthand keyblock and other auxiliary functions, user-installable with ease.

Internal structure

The basic Model 10 Calculator is fully programmable; both data and program steps can be stored in the calculator memory.
Programming is simple because the various keyboard operations become the program instructions: no special language need be learned.
Standard programming features include separate data and program memories, conditional and unconditional branching, direct and indirect data storage and register arithmetic, relocatable programs, subroutines, and the ability to automatically load magnetic cards containing either program steps or data. An additional feature is program editing, which enables programs to be easily debugged and corrected, even though they are already stored in the memory.

The internal structure of the HP 9810A calculator consists of modules, which were designed by the manufacturer to be easily replaceable to simplify potential repairs of the calculator.

The basic modules of the HP 9810A calculator are:








09810-69511 I/O Register
09810-69512 I/O Clock
09810-69513 Micro Processor
09810-69514 ALU Register
09810-69521 Basic ROM Memory
09810-69522 Control Ass’y
09810-69523 M Register
09810-69524 T Register
09810-69525 R/W Memory (Basic)
11218-69526 2036 Register Board
09810-69527 Memory Cage
09810-66502 Mainboard
11219-69550 Printer
09810-69560 Magcard Reader
09810-69530 Keyboard
09810-69541 Display

Modules Cage & Display Board Frame

09810-69581 +5V Power Supply
09810-66582 Misc. Power Supplies
09810-66583 -12V Power Supplies
All major components of the HP 9810A calculator