Pachislot fans and collectors talk in generations: “a 4号機 classic”, “6.5号機 smart slots”. Each generation (号機, gōki) reflects a new set of testing rules. Machines must pass these before a hall can install them, and halls need approval to replace machines (PIWR – law). Every rule change reshaped what machines could do, so the generation tells you a lot about how a machine plays, at a hall or at home.
Most dates below come from Japanese Wikipedia, which is a secondary source. Where we could, we cross-checked with DMM’s Japanese explainer and Sammy’s official page.
Timeline
| Generation | When (approx.) | What changed | Source |
|---|---|---|---|
| Pre-history | 1964 | Olympia, made by a Sega–Taito venture, is recorded as the first reel machine in Japan | ja.wikipedia |
| 0号機 | 1977–1985 | Gemini (Max Shoji, 1977), sold as “American pachinko”. Machines before the 1985 rules are retro-labelled “0号機” | ja.wikipedia |
| 1号機 | 1985 | First generation under formal testing rules | ja.wikipedia |
| 2号機 | 1988 | Credit function (up to 50 credits) | ja.wikipedia |
| 3号機 | 1990 | Third rule set | ja.wikipedia |
| 4号機 | 1992 | Replay introduced, auto-reset, more design freedom. Later sub-versions 4.1 and 4.5 (both 2002), and 4.7 (2004). All 4号機 had to leave halls by 30 Sep 2007 | ja.wikipedia |
| 5号機 | from 2005 | Tighter payout limits, stock systems banned. RT and ART appear, and ART revives the market from about 2010 | ja.wikipedia |
| 6号機 | from 2018 | Machines type-tested under the NPA rule revision of February 2018. New upper and lower payout limits, a cap per advantage zone, BIG bonus capped lower. Ceilings return | ja.wikipedia 6号機 (パチスロ), DMM |
| 6.5号機 | from June 2022 | Net-medal (差枚) limit of 2,400. Advantage zone up to 4,000 games. 19,000-medal ‘complete’ stop | ja.wikipedia 6号機 (パチスロ) |
| Smart slot | Nov 2022 | Electronic medals, unlimited advantage-zone games (smart only), 19,000-medal daily “complete” stop | Sammy |
| 6.6号機 | 2024 (TODO: exact date) | Advantage zone extended from 4,000 to 6,000 games. ‘Bonus Trigger’ for A-types | ja.wikipedia 6号機 (パチスロ) |
Japanese Wikipedia also notes that Mie prefecture only allowed pachislot from 2000 (ja.wikipedia), an interesting regional footnote.
The 4th generation: why collectors love it
The 4号機 era is the stuff of legend. Japanese Wikipedia describes machines with very large single bonuses and AT booms, where single-day payouts drew public criticism. The industry tightened its own rules in 2002 (labelling some machines “4.1”), and certain machines lost their certification in 2003 (ja.wikipedia). Every 4号機 had to leave the halls by 30 September 2007.
At home there’s no money involved, so many collectors seek out these machines for the history and the sounds. See buying a machine for home and the import guide.
The 6th generation in more detail
Japanese Wikipedia summarises the original 6号機 rules like this (ja.wikipedia 6号機 (パチスロ)):
- Short-term upper limits on the payout rate: no more than 220% over 400 games and 150% over 1,600 games.
- Lower limits too, so machines can’t take medals too fast: 33% over 400 games, 40% over 1,600, 50% over 6,000 and 60% over 17,500.
- A cap of 2,400 medals within one 有利区間 (“advantage zone”, the period in which a machine can pay out through AT), with the zone limited to 1,500 games at first.
- Bonus games on normal (A-type) machines capped at 300 medals, against 480 in the 5th generation.
- Ceilings (天井) allowed again. See ceilings explained.
It names HEY! Kagami (Daito Giken), introduced to halls from 1 October 2018, as the first 6号機 to debut. Then came a run of revisions:
| Version | Change (summary) |
|---|---|
| 6.1 (first machine in halls Aug 2020) | Penalty rules eased |
| 6.2 (announced Apr 2021) | Advantage zone extended from 1,500 to 3,000 games. The 2,400-medal cap stays |
| Dec 2021 rule change | Cap redefined as net medals (差枚) 2,400 |
| 6.4 | Advantage-zone lamp no longer mandatory in normal play |
| 6.5 (from Jun 2022) | Advantage zone up to 4,000 games, net cap 2,400, lamp formally optional, 19,000-medal complete function |
| Smart slots | Treated as 6.5 under the industry rules, with no game limit on the advantage zone |
| 6.6 | Advantage zone from 4,000 to 6,000 games. New Bonus Trigger (規定数固定機能) for normal machines: bonus odds are much higher on 1- or 2-medal games than on 3-medal games, the player can’t choose the bet, and no AT or RT is allowed |
Source for all rows: ja.wikipedia 6号機 (パチスロ). TODO: replace with the primary documents from the industry associations (日電協 and 日工組) or the NPA before treating these as authoritative.
“Setting L”: the same article describes a “設定L”, a deliberately low setting some makers added to help machines pass type testing. It wasn’t meant for hall use (ja.wikipedia 6号機 (パチスロ)). It’s a good example of how strict the 6号機 tests were. See settings explained.
What this means for a visitor: you don’t need to know any of it to play. It explains why modern machines have long build-ups and capped runs, why ceilings exist, and why old classics are found only in collections.
Pachinko has generations too, sort of
Pachinko doesn’t use the 号機 naming, but its rules have changed just as much. The CR card system arrived in 1992, payout caps came in 2018, and the yu-time and Lucky Trigger designs followed (ja.wikipedia パチンコ). See pachinko machine types and the history guide.
Quick answers
What does 号機 (gōki) mean?
号機 means 'machine number' and marks a generation of pachislot regulations. Each generation (1号機, 2号機… 6号機) reflects a new set of testing rules that changed how machines could be designed and how much they could pay out.
What generation are machines in parlours today?
6th-generation machines: the later 6.5 and 6.6 versions and smart slots. Japanese Wikipedia records that all 4th-generation machines had to leave halls by 30 September 2007. Earlier generations survive only as collectors' pieces.
Why do collectors talk about 4号機?
4th-generation machines (from 1992) became famous for very large payouts and stock systems. The rules were tightened, and these machines had to leave halls by September 2007. That makes them sought after for home play, where no money is involved.
Can I play an old 4号機 in a Japanese parlour?
No. Halls can only run machines that pass current certification. Retro titles return as new machines built to the current rules, sometimes with the same name.
Sources
- ja.wikipedia – パチスロ (generation history; secondary source)
- ja.wikipedia – 6号機 (パチスロ) (6.0–6.6 rule details; secondary source)
- DMM Pachitown – 6号機 explained (Japanese)
- Sammy – smart pachislot official explainer (Japanese)
- Pachinko Industry Web Reference – game machine certification and law
Facts on this page were last checked against these sources on 4 October 2026. Rules, prices and venues change, so always follow the signs and staff at the venue.
