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Press kit

Writing about this? Take what you need.

Boilerplate, facts, and photography you can use without asking. Everything below is free to publish with credit.

One line

Derby Owners Club, a linked-cabinet Sega arcade game that never got a home release, is being kept running by the community that remembers it.

Short version

Derby Owners Club arrived in arcades in 1999. You raised a racehorse, fed and trained it, and carried it home on a magnetic card so it would still be yours next week. Then you sat in a row of linked seats and raced it on a shared screen the size of a doorway. It never got a home release, so when the cabinets left the arcades that was supposed to be the end of it. A community has since preserved four builds of the game, worked out the undocumented card format by hand, and put real cabinets online so anyone can take a seat from a browser.

Longer version

Derby Owners Club was built around hardware that does not survive well. A full setup is not one machine but a stack: a main two-screen race board plus a satellite cabinet for every player, all linked together. Cabinets shipped in four, six and eight player variants, so a full eight-seat row meant seven other people riding against you at once, each at their own seat.

The part that made it special is also what made it hard to preserve. Your horse did not live in the machine. It lived on a magnetic card in your wallet, and nothing about that card's layout was ever documented. Every field had to be worked out against real cards: the internal stats, the externals, coat, pedigree, running style, and the full record of every race the horse had run. That map is now published openly, along with the tools built from it, because a format only one person understands has not really been preserved.

Four builds are preserved and running: World Edition Rev C and Rev D, and the two Japanese releases, DOC 2000 and the original DOC '99. All four can now save a horse to a card and load it back, which the Japanese versions could not do outside a cabinet until recently.

Facts

1999Arcade debut
4Builds preserved
4 / 6 / 8Player variants
244Horse records decoded
0Ways to play it officially

Two home versions did exist, and both are gone: Derby Owners Club Online on PC (Japan only, 2004, servers closed 2006) and Derby Owners Club -Next Furlong- on iOS and Android (Japan only, 2012, closed January 2019). Both were online services rather than games anyone could own, so when they were switched off nothing was left. The arcade game itself never got a console port.

Two details that tend to interest people who know the game. Rev C and Rev D turn out to be identical across all 244 horse records, which settles a long-running argument about whether the later revision quietly changed the roster. It did not. And the Japanese builds differ from the World Edition far more than a translation would: DOC '99 stores a horse in 28 bytes where the World Edition uses 32.

The open problem, if you want the interesting angle

We can read every byte of a horse and still cannot prove the arithmetic that turns those numbers into a finishing order. That maths is not stored as data anywhere. It is processor code, and reading it means disassembling the game's own instructions.

We know where it lives, we have the entry points, and we have thousands of recorded races to test an answer against. What we do not have is the answer. We would rather say so than publish a guess that sounds authoritative. If you know someone who reads SH-4 assembly, that is the single most useful thing anyone could bring to this project right now.

What to link

If you link one thing, link the preservation page. It explains why the project exists before it asks anyone for anything.

Photography

Free to use with credit. Shot by the project. Click any image for the full resolution file.

A lit row of Derby Owners Club seats with people playing.
doc-row-playersA full row, lit and running, with people in the seats.
A row of lit Derby Owners Club cabinets.
hw-row-litThe row as it stands, powered up.
A lit Derby Owners Club cabinet showing the ranking board.
doc-cabinet-litA single cabinet showing the earnings ranking board.
A Derby Owners Club cabinet opened for service.
doc-cabinet-openedOpened for service. This is most of what keeping them alive looks like.
Two Sega NAOMI cartridges labelled Derby Owners Club 2000.
sw-naomi-cartsSega NAOMI cartridges, labelled by hand at the factory.
Derby Owners Club player cards beside a magnetic card reader.
doc-cards-readerThe horse lived here: a magnetic card, and the reader that reads it back.
Two Japanese Derby Owners Club owner's cards in sleeves.
sw-jp-owner-cardsJapanese owner's cards, the format that took longest to crack.
The Derby Owners Club online lobby showing live cabinets with open seats.
on-lobbyThe online lobby: real cabinets, showing which seats are open.
The two-screen race board showing a race card with twelve horses.
on-race-boardThe board everyone in the row is watching.
Derby Owners Club cabinets arriving on a truck.
doc-arrival-2019Arrival day. Nine machines make one eight-player setup.

Credit as: Derby Owners Club Preservation Project, doc.johnreevesiii.com

Please get this bit right

This project is community run and there is no advertising. Racing is free for everyone. Until November 30, members can pay for a workshop of tools we wrote ourselves (breeding and planning software, and a larger stable). From December 1 those tools are free for everyone and DOC runs on donations.

The online cabinets run on hardware owned by the project. The home Host Pack, retired in August 2026, set up a linked row on your own PC; its successor, DOC Host, lets Winner’s Circle members (every member from December 1) run a cabinet at home that joins the online lobby. Both are built on Flycast, which is open source.

If a piece implies otherwise we would genuinely rather correct it before publication than after.

Contact

The fastest way to reach the people actually doing this is the Discord. It is also where the community talks, and where you will find people who have owned these machines for years.