HP 9825 Projects

Incidentally, CuriousMarc (Jean-Marc Verdiell) is currently deep into his 9825 repair-a-thon. An incredible window into the technology of that time.<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=b-eN93L6yX8&amp;list=PL-_93BVApb58Hy846J52DT8FeF9USYJUn" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=b-eN93L6yX8&amp;list=PL-_93BVApb...</a>

I don&#x27;t know the precise history, but the corporate decision to work on these self contained computers was the reason why Steve Wozniak left HP to found Apple Computer with Steve Jobs.<p>Still, paging through Byte Magazine and looking at all of the things that I couldn&#x27;t afford at the time, the HP computers definitely seemed pretty cool to me, and I&#x27;m sure the quality of HP calculators lent to the appeal.

This is a predecessor of the computer that I most crave, the HP-87:<p><a href="http:&#x2F;&#x2F;www.oldcomputers.net&#x2F;hp85.html" rel="nofollow">http:&#x2F;&#x2F;www.oldcomputers.net&#x2F;hp85.html</a><p>(I wanted the HP-87 since before the Series 80 became the standard issue computer in the great Brutalist&amp;retro ambiance of the video game Control. I would be sure to get a HP-87 without any supernatural phenomena.)

I finished one other project - playing &quot;MasterMind&quot; against the computer (you know, where you have to guess five colour pins) with output done on the internal little printer. After that I had started one one other project (an 8085 assembly language simulator), when first the controller for the external 8&#x27;&#x27; floppy drive stopped working, effectively bricking it, and shortly after that the handful of tape cartridges I had. Mind you, at the time everything was 15 years old or so, so I couldn&#x27;t really blame the equipment.

I used one of those big machines (not this one) back in the day. But, for my money, the most beautiful calculator in history was the HP25 (<a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;HP-25" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;HP-25</a>). Clear keys, spaced for errorless entry, and with that wonderful levering action that made it unnecessary to look up at the display to see if you entered the number correctly. The key colours, sublime. And the back, shaped to perfection.<p>A pinnacle of design.

I wished they would have some hints regarding the applications of this &quot;third generation desktop computer&quot;. Those things had 32KiB of RAM -- what were they using that for? Some felt even the need for a 32KiB RAM expansion. Clearly those were not used as desktop calculators, but what <i>were</i> they doing?

I once (1992?) calculated mandelbrot sets on one of these. 400x400, output to an external thermo printer as the one-line display had, well, only one line. With a calculation depth of 256 it took about 48 hours to produce one set.

Love the disclaimer at the bottom, &quot;and don’t let nobody tell you different!&quot;