IBN 5100#
| Manufacturer | IBN Corporation |
| Released | 1975 |
| Class | Portable (luggable) personal computer |
| Mass | ~25 kg ("portable") |
| CPU | Custom 16-bit PALM-architecture processor |
| Display | 5-inch monochrome CRT, 64 × 16 characters |
| Storage | Quarter-inch cartridge tape, 204 KB |
| Languages | BASIC, APL |
| Hidden feature | Undocumented multibyte decoding routine |
| Significance | Only machine able to decode SERN's archived LHC reports |
| Known units in Akihabara | One (worldline-dependent) |
| Current owner | Future Gadget Laboratory (briefly) |
The IBN 5100 is a 1975 luggable computer of no particular distinction — except for one undocumented capability that made a forty-year-old machine the most contested object in Akihabara: it is the only computer that can read the archaic multibyte encoding SERN used for its earliest internal reports. Anyone wanting to read what SERN's archives say about time travel needs an IBN 5100 first. This includes, at various points, SERN itself, a round-up of internet conspiracy theorists, and the Future Gadget Laboratory.
When Daru first breached SERN's internal network, the juiciest directories — decades of reports filed under a project name that translates loosely to "Z Program" — turned out to be stored in a dead encoding no modern toolchain could parse. Not encrypted: encoded, in a proprietary interchange format IBN shipped briefly in the mid-1970s and documented nowhere public.
The IBN 5100's firmware contains a translation routine for exactly this format. IBN never advertised it; the routine appears to have been a contractual deliverable for a single large customer, and the machine's service manual refers to it only as "extended interchange support." Whether that single large customer was SERN is the kind of question that gets a wiki page flagged #lore, but the circumstantial case writes itself.
The chain of need
Daru's hack → unreadable archives → need IBN 5100 → search Akiba → shrine donation → decode → regret. See Episode 05 onward.
graph TD;
SERNArchive-->LegacyEncoding;
LegacyEncoding-->IBN5100;
IBN5100-->DecodedReports;
Exactly one unit was known to survive in Akihabara, donated years ago to the Yanabayashi Shrine and kept in storage as an offering nobody knew what to do with. The lab's acquisition of it — and the worldline shifts that repeatedly un-acquired it — form one of the stranger subplots of the lab's first summer. On some worldlines the machine was never donated at all; on at least one it was destroyed in the 1990s. Its presence or absence became an informal marker for which Alpha worldline the lab was currently on, a job later done properly by the Divergence Meter.
| Property | Value |
|---|---|
| Serial number | 5100-J-04471 |
| Condition | Working; CRT slightly burned |
| Shrine storage duration | ~10 years |
| Retrieval attempts | 3 (two undone by worldline shifts) |
| Final disposition | Worldline-dependent |
If you have found what you believe to be an IBN 5100 at a flea market, do not post about it publicly. This advice is offered without further explanation. See Episode 08 for what happens to people who don't take it.
A single-board design around IBN's PALM processor, executing an interpreter in microcode: the machine runs BASIC and APL natively in the sense that its "machine language" is itself emulated. This baroque design is precisely why the decoding routine survives — it lives in the microcode ROM, not on replaceable media.
Quarter-inch tape cartridges, a 5-inch internal CRT, and an external video jack. Daru interfaced it to a modern network by wiring the video output to a capture card and pointing OCR software at the result — a solution he describes as "warcrime-adjacent, but shipping."
The PALM microcode has never been fully dumped; emulators reproduce the BASIC environment but not the interchange decoder. As of this writing the physical machine remains irreplaceable.
Working 5100s trade hands for figures that would fund the lab for a year. The Radio Kaikan retro-computing floor lists one perhaps once a decade; the last public listing was withdrawn within four hours under circumstances nobody at the shop will discuss. Rumors of a second Akihabara unit surface annually and have never survived contact with a camera.1
The real-world machine this article shamelessly resembles is documented at IBM 5100. Within this wiki, the IBN 5100's story is inseparable from SERN's LHC archives, the shrine that sheltered it, and Okabe's repeated attempts to keep it in one worldline long enough to finish a decode job. A planned page on the PALM architecture has not been written yet.
Footnotes#
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The one photograph that allegedly exists shows, on close inspection, a beige sewing machine. ↩