# Continuous memory

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Continuous_memory
> Markdown URL: https://mediated.wiki/source/Continuous_memory.md
> Source: https://en.wikipedia.org/wiki/Continuous_memory
> Source revision: 1046882447
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

The term '''continuous memory''' was coined by [Hewlett-Packard (HP)](/source/Hewlett-Packard) to describe a unique feature of certain [HP calculators](/source/HP_calculators) whereby the calculator could internally sustain most, or in later models - all, of the contents of user memory (via battery-backed [CMOS](/source/CMOS) memory).  Since its introduction on the [HP-25C](/source/HP-25C), this feature slowly evolved by model to eventually mean maintaining the contents of nearly all calculator memory, including system and scratch RAM, options, settings, flags, and other calculator state information.

Before the introduction of the HP-25C in 1976, all calculator [random-access memory (RAM)](/source/Random-access_memory) was volatile, i.e. its contents (esp. user data in storage registers and any user programs) were cleared when the calculator was turned off.  Three early models with this improved, continuous memory - the HP-25C, [HP-29C](/source/HP-29C), and [HP-19C](/source/HP-19C) - actually had the words "'' Continuous Memory ''" printed in conspicuous, white script on the bottom margin of their faceplates.  The "'''C'''" in the model designations was to distinguish those models within HP's calculator product line.  HP did not print this phrase on subsequent, featured models because the novelty of continuous memory had by then faded and also because it could no longer claim it as a feature unique to HP calculators (Texas Instruments would later call their identical feature "[Constant Memory](/source/TI_Constant_Memory)").  At introduction over the next 9 years (approx. 1979–1987), subsequent HP models so featured simply had designations in which the letter "'''C'''" followed the model number, e.g. the [HP-34C](/source/HP-34C) and the [Voyager series](/source/HP_Voyager_series) [HP-10C](/source/HP-10C), [HP-11C](/source/HP-11C), [HP-12C](/source/HP-12C), [HP-15C](/source/HP-15C) and [HP-16C](/source/HP-16C).

==References==
*{{cite book|author=Hearst Magazines|title=Popular Mechanics|url=https://books.google.com/books?id=VtkDAAAAMBAJ&pg=PA68|date=August 1982|publisher=Hearst Magazines|pages=68–|issn=0032-4558}}

{{HP calculators}}

continuous memory

---
Adapted from the Wikipedia article [Continuous memory](https://en.wikipedia.org/wiki/Continuous_memory) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Continuous_memory?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.