Apple Desktop Bus

Definition of Apple Desktop Bus

Apple Desktop Bus (ADB) is a proprietary data transfer protocol and connector system developed by Apple Inc. in the 1980s. It was primarily used for connecting input devices like keyboards, mice, and graphics tablets to Apple desktop computers. However, the ADB technology has now been phased out and replaced by USB and other more modern interface standards.


Apple Desktop Bus in phonetics is: /ˈæpəl ˈdɛskˌtɒp bʌs/

Key Takeaways

  1. Apple Desktop Bus (ADB) is a proprietary, low-speed, bidirectional serial communication system developed by Apple Inc. in the mid-1980s, primarily used for connecting peripherals like keyboards, mice, and graphics tablets to Macintosh computers.
  2. ADB devices can be daisy-chained together, allowing multiple peripherals to connect to a single ADB port on the Mac, reducing cable clutter and simplifying system expansion. This feature distinguishes ADB from its contemporaries, such as IBM’s PS/2 interface.
  3. Though versatile and widely used in early Macintosh systems, ADB was ultimately replaced by USB in the late 1990s, starting with the iMac G3. USB offers higher transfer speeds, greater device compatibility, and a standardized interface across multiple platforms, leading to ADB’s obsolescence.

Importance of Apple Desktop Bus

The technology term “Apple Desktop Bus” (ADB) is important because it was an innovative low-speed serial computer bus designed by Apple Inc.

in the mid-1980s.

It aimed to simplify the process of connecting peripherals like keyboards, mice, graphics tablets, and other input devices to Apple computers.

By using a daisy-chaining scheme, ADB enabled multiple devices to connect to a single bus line, thus reducing the clutter of multiple cables and freeing up expansion slots.

Despite being eventually replaced by USB as a more universal and faster connection type, ADB made a significant impact on the evolution of computer connectivity standards and played a pivotal role in simplifying and streamlining the computer peripheral ecosystem of its time.


The Apple Desktop Bus (ADB) is a technology that was designed to enhance the interaction between various peripheral devices and Apple’s personal computers. The primary purpose of ADB was to streamline connections and improve the overall user experience by allowing users to connect multiple devices, such as keyboards, mice, and graphics tablets, to their computers using a single, daisy-chainable interface. This technology simplified the process of attaching peripherals and eliminated the need for numerous, separate connectors on the computer.

ADB was introduced in 1986 as a part of Apple’s 16-bit Macintosh systems, and was eventually also used in the Apple IIGS, the Power Macintosh and PowerBook laptops. ADB was beneficial in several ways. Firstly, it helped users in consolidating the clutter of multiple wires and connectors.

Instead, they were able to use a single 4-pin connector for all peripherals, which could be linked together by connecting one device to another in a daisy chain configuration. This made the process of setting up and managing devices more efficient and user-friendly. Furthermore, ADB featured a built-in power supply that allowed the connected peripherals to draw power directly from the bus.

This eliminated the need for separate power supplies for each device, further simplifying the overall setup. Although ADB was eventually replaced by USB and other more advanced connectivity options, it played a significant role in the evolution of computer peripherals and user interfaces, laying the foundation for the streamlined connections we enjoy today.

Examples of Apple Desktop Bus

Apple Desktop Bus (ADB) is a proprietary bit-serial peripheral bus used by Apple Inc. for connecting low-speed devices to their computers. It was introduced in 1986 on the Apple IIGS computer system. Here are three real-world examples of this technology:

Apple Keyboard: The Apple Desktop Bus was used to connect keyboards to various Apple computer models, such as the Apple IIgs, Macintosh II, and Macintosh SE. This made it easier for users to interact with their computer systems, enabling them to type commands and input data using a physical keyboard instead of relying solely on the mouse.

Apple Mouse: ADB was also used for connecting Apple’s early pointing devices like the Apple Desktop Bus Mouse (ADB Mouse) and later versions such as the ADB Mouse II. These mice were designed for use with Apple computer systems and provided users with greater control over their GUI-based operating systems, making it easier to navigate and interact with onscreen elements.

Apple Graphics Tablet: Apple developed a graphics tablet that connected using the ADB port. The Apple Graphics Tablet was a pressure-sensitive input device that allowed artists and designers to create digital artwork directly on their Apple computers. Using the ADB connection, the tablet was able to send precise pen movements and pressure data to the computer, which could then be interpreted by various drawing and design software.

Apple Desktop Bus FAQ

1. What is Apple Desktop Bus?

Apple Desktop Bus (ADB) is a proprietary bit-serial peripheral bus connecting low-speed devices to computers. It was introduced on the Apple IIGS in 1986 and used on all later Apple Macintosh and Apple PowerBook computers until it was phased out in favor of USB in 1999.

2. What devices are compatible with Apple Desktop Bus?

ADB was used to connect devices such as keyboards, mice, graphics tablets, trackballs, joystick controllers, and other low-speed peripherals to Apple computers. This allowed for simplified device management and reduced cable clutter.

3. Is Apple Desktop Bus still in use today?

No, ADB was phased out in favor of USB in 1999, which has since become the industry standard for connecting peripherals to computers. The introduction of the iMac G3 eliminated ADB ports and supported USB instead.

4. Can I use ADB devices with modern computers?

It is possible to use ADB devices with modern computers through the use of ADB-to-USB converters. This allows older peripherals such as ADB keyboards and mice to be used with USB ports on current devices.

5. What is the benefit of Apple Desktop Bus technology?

ADB provided a simple, low-cost method for connecting low-speed devices such as keyboards and mice to Apple computers. It featured daisy-chaining, which reduced cable clutter and eased device management by allowing multiple devices to be connected to a single ADB port.

Related Technology Terms

  • Peripheral Connection
  • ADB Protocol
  • Macintosh Computers
  • Input Devices
  • Macintosh System Software

Sources for More Information


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