--- title: Java Ring Restored After Nearly 30 Years | daily.dev description: In the late 1990s, Sun Microsystems handed out Java Rings at developer conferences as a demonstration of Java-powered wearable authentication. Daisuke Yamazaki... canonical: https://daily.dev/posts/java-ring-restored-after-nearly-30-years-t148wwvfr twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Java Ring Restored After Nearly 30 Years | daily.dev og:description: In the late 1990s, Sun Microsystems handed out Java Rings at developer conferences as a demonstration of Java-powered wearable authentication. Daisuke Yamazaki... og:url: https://daily.dev/posts/java-ring-restored-after-nearly-30-years-t148wwvfr og:image: https://api.daily.dev/og/posts/T148WWvFr.png og:image:alt: Java Ring Restored After Nearly 30 Years og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Java Ring Restored After Nearly 30 Years **[Hackaday](https://daily.dev/sources/hackaday)** · 3 min read · 1 upvotes · 0 comments ## Summary In the late 1990s, Sun Microsystems handed out Java Rings at developer conferences as a demonstration of Java-powered wearable authentication. Daisuke Yamazaki recently acquired one of these collector's items and documented the process of reviving it. Challenges included finding a Blue Dot adapter for the 1-Wire bus, recovering a 32-bit Dallas Semiconductor IDE from the Wayback Machine, and dealing with Java compatibility issues requiring a downgrade to Java 1.8. A CRC error investigation revealed the built-in lithium backup battery had died, sealing the device's fate as e-waste — until a Japanese TV feature connected Yamazaki with others who helped replace the battery. The restoration confirmed that original coffee-preference data stored in battery-backed RAM was lost, but the ROM retained the JVM, allowing new programs to be written to the device. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why wouldn't the old Java Ring IDE software work with a modern Java runtime like Java 25? The Dallas Semiconductor IB-DE IDE was a 32-bit Java binary relying on communication APIs that have since been removed from modern Java, so it failed under Java 25. Downgrading to 32-bit Java 1.8, which still included those older communication APIs, resolved the compatibility problem and allowed the software to talk to the ring again. _daily.dev surfaces stories like this for developers curious about legacy Java runtime quirks and long-term API removals._ ### What causes a Java Ring or iButton device to stop working after decades of storage? A dead built-in lithium backup battery causes CRC errors on the 1-Wire bus and wipes any data stored in battery-backed RAM, including things like saved user preferences. The JVM itself survives because it lives in ROM, so once the battery is replaced, new programs can be written to the device and persist across sessions again. _Anyone reviving old embedded hardware can find similar restoration deep-dives curated on daily.dev._ ## Similar posts on daily.dev - [Time Frog Color Is A Game Boy Color On Your Wrist](https://daily.dev/posts/time-frog-color-is-a-game-boy-color-on-your-wrist-wvkbojr8a) · Hackaday · 0 upvotes · 0 comments - [Nokia N900 Necromancy](https://daily.dev/posts/nokia-n900-necromancy-8urfeemql) · Hacker News · 4 upvotes · 0 comments - [Computers that I never had: the Acorn A3020](https://daily.dev/posts/computers-that-i-never-had-the-acorn-a3020-hspqvpdsc) · Two Stop Bits · 4 upvotes · 1 comments - [My Anti AI computer](https://daily.dev/posts/my-anti-ai-computer-vqs0dbnds) · Lobsters · 0 upvotes · 0 comments - [An Analog Reservoir Computer Chip Could Power Wearables](https://daily.dev/posts/an-analog-reservoir-computer-chip-could-power-wearables-g82fxrjlc) · IEEE Spectrum · 1 upvotes · 0 comments --- Tags: [#java](https://daily.dev/tags/java), [#embedded](https://daily.dev/tags/embedded), [#retrocomputing](https://daily.dev/tags/retrocomputing) [View this post on daily.dev](https://daily.dev/posts/java-ring-restored-after-nearly-30-years-t148wwvfr) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Java Ring Restored After Nearly 30 Years","url":"https://daily.dev/posts/java-ring-restored-after-nearly-30-years-t148wwvfr","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/java-ring-restored-after-nearly-30-years-t148wwvfr"},"datePublished":"2026-07-21T11:20:07.847Z","dateModified":"2026-09-14T06:38:05.279Z","description":"In the late 1990s, Sun Microsystems handed out Java Rings at developer conferences as a demonstration of Java-powered wearable authentication. 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