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<title>Continuous memory</title>

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Continuous memory</span></span>

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<div id="mw-content-text" class="mw-body-content mw-content-ltr" lang="en" dir="ltr"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><p>The term <b>continuous memory</b> was coined by <a href="Hewlett-Packard" title="Hewlett-Packard">Hewlett-Packard (HP)</a> to describe a unique feature of certain <a href="HP_calculators" title="HP calculators">HP calculators</a> whereby the calculator could internally sustain most, or in later models - all, of the contents of user memory (via battery-backed <a href="CMOS" title="CMOS">CMOS</a> memory). Since its introduction on the <a href="HP-25C" class="mw-redirect" title="HP-25C">HP-25C</a>, 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.

</p><p>Before the introduction of the HP-25C in 1976, all calculator <a href="Random-access_memory" title="Random-access memory">random-access memory (RAM)</a> 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, <a href="HP-29C" class="mw-redirect" title="HP-29C">HP-29C</a>, and <a href="HP-19C" class="mw-redirect" title="HP-19C">HP-19C</a> - actually had the words "<i> Continuous Memory </i>" printed in conspicuous, white script on the bottom margin of their faceplates. The "<b>C</b>" 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 "<a href="TI_Constant_Memory" class="mw-redirect" title="TI Constant Memory">Constant Memory</a>"). At introduction over the next 9 years (approx. 1979–1987), subsequent HP models so featured simply had designations in which the letter "<b>C</b>" followed the model number, e.g. the <a href="HP-34C" title="HP-34C">HP-34C</a> and the <a href="HP_Voyager_series" class="mw-redirect" title="HP Voyager series">Voyager series</a> <a href="HP-10C" class="mw-redirect" title="HP-10C">HP-10C</a>, <a href="HP-11C" class="mw-redirect" title="HP-11C">HP-11C</a>, <a href="HP-12C" title="HP-12C">HP-12C</a>, <a href="HP-15C" title="HP-15C">HP-15C</a> and <a href="HP-16C" title="HP-16C">HP-16C</a>.

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<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite id="CITEREFHearst_Magazines1982" class="citation book cs1">Hearst Magazines (August 1982). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=VtkDAAAAMBAJ&pg=PA68"><i>Popular Mechanics</i></a>. Hearst Magazines. pp. 68–. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0032-4558">0032-4558</a>.</cite></li></ul>

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</style><div id="Hewlett-Packard_(HP)_calculators246" style="font-size:114%;margin:0 4em"><a href="HP_calculators" title="HP calculators"><span style="color:#FFFFFF;">Hewlett-Packard (HP) calculators</span></a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color: #FFFFFF"><a href="Comparison_of_HP_graphing_calculators" title="Comparison of HP graphing calculators">Graphing</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="HP_Prime" title="HP Prime">Prime</a></li>

<li><a href="HP_Xpander" title="HP Xpander">Xpander</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color: #FFFFFF">Scientific programmable</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="HP_9800_series" title="HP 9800 series">9800 series</a>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color: #FFFFFF">Scientific non-programmable</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li>6s Solar</li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color: #FFFFFF">Financial and business</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="HP-12C#12c_Platinum" title="HP-12C">Platinum</a></li>

<li><a href="HP-12C#12c_Prestige" title="HP-12C">Prestige</a></li></ul></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color: #FFFFFF">Other</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="HP_CalcPad_series" class="mw-redirect" title="HP CalcPad series">CalcPad</a>

<li>QuickCalc</li>

<li>EasyCalc</li>

<li>OfficeCalc</li>

<li>PrintCalc</li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color: #FFFFFF">Related topics</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="FOCAL_(Hewlett-Packard)" class="mw-redirect" title="FOCAL (Hewlett-Packard)">FOCAL</a></li>

<li><a href="Synthetic_programming_(HP-41)" title="Synthetic programming (HP-41)">Synthetic programming</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;background-color: #FFFFFF">Emulation software</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

</div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2021-09-27" href="https://en.wikipedia.org/wiki/?title=Continuous_memory&oldid=1046882447">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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