# How Wozniak Made the Apple II Display Color Graphics > Steve Wozniak's 1977 patent for a circuit that allowed a home computer to display stable, sharp color graphics on a standard television screen. - **Patent:** US 4136359 - **Original title:** Microcomputer for use with video display - **Owner:** Apple Computer Inc - **Granted:** 1979 - **Status:** Public domain (expired) - **Times cited:** 29 - **Field:** consumer_electronics, semiconductors ## What it does This patent describes a timing circuit that synchronizes a computer's digital signals with the analog signal requirements of a standard television. Because televisions use a specific color frequency (the color subcarrier), simply outputting digital data often resulted in blurry or 'crawling' colors. Wozniak's invention uses a horizontal synchronization counter that is locked to an odd-submultiple of the color frequency. By introducing a specific 'delayed' count into this cycle, the system ensures that the color phase remains consistent across different scan lines, preventing the color distortion that would otherwise occur on a consumer CRT display. ## What it does NOT cover - Does not cover non-raster scan display technologies like modern LCD or OLED panels. - Does not cover software-based color generation methods that do not rely on hardware-level timing synchronization. - Does not cover high-definition (HD) or 4K signal timing protocols. - Does not cover the specific logic used to store the pixel data itself, only the timing synchronization for the output. ## The clever bit Wozniak realized that if you force the computer's horizontal sync to be an odd-submultiple of the color subcarrier, the phase of the color signal automatically corrects itself every other line, eliminating the need for complex and expensive external hardware. ## Real-world examples 1. Apple II personal computer 2. Early home video game consoles using NTSC television signals ## Why it matters This patent was the technical backbone of the Apple II, the machine that effectively launched the personal computer industry. By allowing the Apple II to plug into an affordable, off-the-shelf television instead of an expensive professional monitor, Wozniak made home computing commercially viable for the first time. ## Frequently asked questions ### What does How Wozniak Made the Apple II Display Color Graphics cover? Steve Wozniak's 1977 patent for a circuit that allowed a home computer to display stable, sharp color graphics on a standard television screen. ### Who owns patent US 4136359? Apple Computer Inc owns this patent, granted in 1979. ### 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 4136359 cited by? This patent has been cited by 29 later patents that build on its ideas. ### What problem does this patent solve? This patent was the technical backbone of the Apple II, the machine that effectively launched the personal computer industry. By allowing the Apple II to plug into an affordable, off-the-shelf television instead of an expensive professional monitor, Wozniak made home computing commercially viable for the first time. ### What does this patent NOT cover? Does not cover non-raster scan display technologies like modern LCD or OLED panels. **Full plain-English explainer:** https://patentbrief.org/patent/us/4136359/apple-ii-personal-computer **Original patent:** https://patents.google.com/patent/US4136359 --- _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 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 Early Television Systems Isolated Specific Colors for Special Effects](https://patentbrief.org/patent/us/3678182/chroma-key-green-screen) — A 1971 circuit design that allowed television equipment to detect a specific color in a video signal, enabling the green-screen effects we see in modern weather forecasts and movies. - [How Touchscreens Precisely Align Signals to Detect Your Touch](https://patentbrief.org/patent/us/8493330/individual-channel-phase-delay-scheme) — Apple's patent describes a way for touchscreens to adjust the timing of internal electrical signals so they perfectly match the signals coming from your finger, making touch detection more accurate. - [The First Digital Camera's Core Technology](https://patentbrief.org/patent/us/4131919/digital-camera-electronic-still) — Kodak's 1978 patent on the fundamental technology for capturing, processing, and storing digital images using a CCD sensor and magnetic tape. - [How Douglas Engelbart Invented the Computer Mouse](https://patentbrief.org/patent/us/3541541/computer-mouse-input-device) — The 1970 patent for the X-Y position indicator, better known as the computer mouse, which allowed users to move a cursor across a screen for the first time.