# HP-25

> 1975-1978 calculator by Hewlett-Packard

**Wikidata**: [Q608913](https://www.wikidata.org/wiki/Q608913)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/HP-25)  
**Source**: https://4ort.xyz/entity/hp-25

## Summary
The HP-25 is a programmable calculator produced by Hewlett-Packard between 1975 and 1978. It was one of the first handheld calculators to combine programmability with reverse Polish notation (RPN), making it a significant tool for engineers, scientists, and students. As part of HP's "Classic" series, it built on the success of earlier models like the HP-35.

## Key Facts
- **Production dates**: 1975–1978.
- **Manufacturer**: Hewlett-Packard (HP), a U.S.-based information technology company founded in 1939.
- **Type**: Programmable calculator using reverse Polish notation (RPN).
- **Aliases**: HP25.
- **Notable features**: Could store up to 49 programming steps; used magnetic cards for program storage.
- **Legacy identifiers**: Library of Congress authority ID (sh85062687), National Library of Israel J9U ID (987007531304505171).
- **Cultural impact**: Featured in multiple Wikipedia languages (English, German, Spanish, French, Japanese, Slovene) and a dedicated Wikimedia Commons category.

## FAQs
### Q: When was the HP-25 produced?
A: The HP-25 was manufactured by Hewlett-Packard from 1975 to 1978, making it a key device in the early era of programmable calculators.

### Q: What made the HP-25 unique?
A: It was one of the first handheld calculators to offer programmability, allowing users to automate repetitive calculations using magnetic storage cards and reverse Polish notation (RPN).

### Q: Is the HP-25 still relevant today?
A: While discontinued, the HP-25 remains historically significant as a precursor to modern computing tools and is collectible among calculator enthusiasts. Its design influenced later HP models and the broader calculator industry.

## Why It Matters
The HP-25 played a pivotal role in democratizing access to programmable computing. Before its release, programmable calculators were often bulky and expensive, limiting their use to specialized fields. By combining affordability, portability, and the ability to store instructions, the HP-25 empowered professionals and students to solve complex problems more efficiently. Its use of magnetic cards for program sharing also fostered collaboration, laying groundwork for later data-transfer technologies. As one of HP’s most iconic early calculators, it exemplified the company’s innovation in merging cutting-edge engineering with user-friendly design—a philosophy that defined HP’s dominance in the calculator market for decades.

## Notable For
- **Firsts**: One of the earliest handheld programmable calculators, setting a standard for compact, user-programmable devices.
- **Technology**: Utilized reverse Polish notation (RPN) for efficient calculation workflows, a hallmark of HP’s calculator design.
- **Storage innovation**: Employed magnetic cards to save and transfer programs, enhancing usability in educational and professional settings.
- **Cultural legacy**: Featured in academic and technical literature, with dedicated archival efforts (e.g., Library of Congress and Wikimedia Commons documentation).

## Body

### Production Timeline
- **1975**: Released as part of HP’s "Classic" calculator series, succeeding the groundbreaking HP-35 (1972).
- **1978**: Discontinued after a three-year production run, succeeded by models like the HP-29C and HP-41C.

### Technical Specifications
- **Programming capacity**: Up to 49 steps (later expanded in models like the HP-25C with continuous memory).
- **Display**: Light-emitting diode (LED) screen showing four digits.
- **Power**: Required batteries for operation, with an optional AC adapter.

### Design and Features
- **Reverse Polish Notation (RPN)**: Eliminated the need for parentheses, streamlining complex calculations.
- **Magnetic card reader**: Allowed users to save and load programs, a novel feature for handheld devices at the time.
- **Portability**: Designed for handheld use, reflecting HP’s focus on engineering tools for fieldwork.

### Legacy and Impact
- **Educational use**: Widely adopted in schools and universities to teach programming and computational thinking.
- **Professional applications**: Used in aerospace, engineering, and finance for tasks like statistical analysis and financial modeling.
- **Collectibility**: Remains sought after by collectors due to its historical significance and durable build quality.

## References

1. [Source](https://github.com/JohnMarkOckerbloom/ftl/blob/master/data/wikimap)
2. Freebase Data Dumps. 2013
3. National Library of Israel Names and Subjects Authority File