# 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

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._