# How Early Video Games Synchronized Gameplay Over Modems > A 1998 patent describing a method to keep two remote video games in sync by exchanging command signals and timing codes over a modem connection. - **Patent:** US RE36574 - **Original title:** USRE36574E - Video game - **Owner:** MILTON HAROLD W - **Granted:** 2000 - **Status:** Public domain (expired) - **Times cited:** 16 - **Field:** consumer_electronics, gaming, telecommunications ## What it does This patent describes a hardware assembly that sits between a video game console and a modem to enable remote multiplayer gaming. It captures player inputs (like button presses) from the local console and receives similar inputs from a remote player via a data link. A synchronizer component then ensures these two sets of inputs are fed into the game's processor at the same time. It also uses a counting mechanism to track when the game states drift apart; if the synchronization codes don't match for a set number of cycles, the system retrieves stored player parameters to re-align the games. ## What it does NOT cover - Does not cover modern high-speed internet multiplayer architectures that rely on server-side state reconciliation. - Does not cover wireless or Bluetooth-based controller synchronization. - Does not cover cloud gaming where the game logic runs on a remote server rather than a local console. - Does not cover synchronization methods that do not utilize a specific local and remote synchronization code comparison. ## The clever bit Instead of trying to sync the entire game state (which was too much data for 1990s modems), it only synchronizes the input commands and uses a counter to detect when the two consoles have drifted out of sync. ## Real-world examples 1. Early dial-up modem adapters for 8-bit and 16-bit consoles 2. Peer-to-peer multiplayer configurations for early PC gaming 3. Modem-based game link peripherals ## Why it matters This patent represents an era when developers were solving the fundamental problem of 'lag' and state divergence in early dial-up multiplayer gaming. It highlights the transition from local-only play to the networked experiences that define modern gaming, specifically addressing how to keep two consoles running the same game logic simultaneously over slow, unreliable phone lines. ## Frequently asked questions ### What does How Early Video Games Synchronized Gameplay Over Modems cover? A 1998 patent describing a method to keep two remote video games in sync by exchanging command signals and timing codes over a modem connection. ### Who owns patent US RE36574? MILTON HAROLD W owns this patent, granted in 2000. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US RE36574 cited by? This patent has been cited by 16 later patents that build on its ideas. ### What problem does this patent solve? This patent represents an era when developers were solving the fundamental problem of 'lag' and state divergence in early dial-up multiplayer gaming. It highlights the transition from local-only play to the networked experiences that define modern gaming, specifically addressing how to keep two consoles running the same game logic simultaneously over slow, unreliable phone lines. ### What does this patent NOT cover? Does not cover modern high-speed internet multiplayer architectures that rely on server-side state reconciliation. **Full plain-English explainer:** https://patentbrief.org/patent/us/RE36574/game-boy **Original patent:** https://patents.google.com/patent/USRE36574 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Modems Use Guard Time to Switch Between Data and Commands](https://patentbrief.org/patent/us/4549302/hayes-modem-escape-sequence) — This patent describes a method for modems to safely switch from sending data to accepting commands without accidentally triggering that switch while transmitting normal files. - [How the First Home Video Game Console Worked](https://patentbrief.org/patent/us/3659285/video-game-console-magnavox) — Ralph Baer's 1969 patent for the Magnavox Odyssey, the first home video game system, which generated controllable dots on a standard television screen using analog circuitry. - [How Cable Modems Fix Signal Distortions Before Sending Data](https://patentbrief.org/patent/us/6665308/apparatus-and-method-for-equalization-in-distributed-digital-data-transmission-systems) — A method for cable modems to pre-filter data so it arrives clearly at the central office, preventing signal errors caused by the messy physical wires between them. - [How Nintendo's Wii Remote Tracks Motion and Infrared Light](https://patentbrief.org/patent/us/RE45905/walkman-portable-cassette-player) — A patent describing the Wii Remote's technology for tracking physical movement and infrared light to control video games wirelessly. - [How Multiple Computers Share a Network Cable Without Crashing](https://patentbrief.org/patent/us/4063220/ethernet-packet-network) — This patent describes how multiple computers can share a single communication cable by listening for other transmissions and stopping their own if a collision occurs, then trying again later.