There is a surviving software demo for the HP 9845C that needed two tapes, more than 4,000 lines of BASIC, a light pen, and enough graphics tricks to make a 1980 computer look like it was trying to escape the decade.
HP9845.net documents the package in unusually good detail. The demo contains 36 cases spread across color graphics, engineering, scientific work, management graphics, and advanced graphics. The machine could display up to 4,913 colors, and the software demonstrates wireframes, shaded 3D surfaces, ordered dithering, data visualization, interactive light-pen control, mapping, architecture, stress analysis, astronomy, and even a small gravity game.
The name attached to the demo makes the page even stranger: Colin Cantwell.
Cantwell worked on spacecraft designs for Star Wars, including early concepts connected with the X-wing, TIE fighter and Star Destroyer. The HP archive says he also consulted on the 9845C color system and later programmed the tactical NORAD screens seen in WarGames using an HP 9845C.
The software survived by inches
Magnetic media does not care that something is historically interesting.
The archive explains that surviving demo tapes commonly suffer from deterioration, and multiple versions of the software made reconstruction difficult. A complete set of files eventually turned up on a backup disk held by another HP collector, allowing the full demo to run again.
That one paragraph contains most of digital preservation: old media fails, incomplete copies multiply, somebody kept a backup, and suddenly the thing is recoverable.
The page does more than describe it. There is a large screenshot gallery, the complete demo disk image, the original demo guide, video footage, and instructions for running the software through an HP 9845C emulator based on MAME.
A technical page that earns its URL
This is the kind of old-web material search engines are good at only after somebody has done the hard part. The page ties together a specific computer, part numbers, software, a designer, screenshots, damaged media, downloadable artifacts, and enough context to explain why any of it matters.
Webmasters building historical resources should notice the pattern: preserve the files, but preserve the explanation around the files too.
This HP page was found in the larger CacheRat Ancient Web research list.
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The screenshots alone are worth the visit. The fact that you can still download the demo is better.