VMEbus

VMEbus

VMEbus (Versa Module Europa bus) is a computer bus standard originally developed for the Motorola 68000 line of CPUs in 1981. It was first developed by Motorola, Mostek, Philips, and Thomson-CSF and has since been standardized by the IEEE as IEEE 1014-1987. VMEbus is widely used in industrial, commercial, and military applications due to its robustness and versatility.

History

The VMEbus was developed as a result of the need for a standardized bus system that could support multiple processors and a variety of peripheral devices. The initial development was driven by the requirements of the Motorola 68000 microprocessor, which necessitated a bus system that could handle its advanced features. The VMEbus quickly gained popularity due to its flexibility and scalability, allowing it to be used in a wide range of applications.

Technical Specifications

VMEbus is a parallel bus system that supports data widths of 8, 16, 24, and 32 bits. It operates at a clock speed of 16.67 MHz and supports multiple masters and slaves, allowing for complex configurations and high data throughput. The bus uses a Eurocard form factor, with standard card sizes of 3U and 6U.

Addressing and Data Transfer

VMEbus supports both 16-bit and 32-bit addressing, allowing for a large address space. Data transfer on the VMEbus can be performed using several methods, including single-cycle transfers, block transfers, and burst transfers. The bus also supports interrupt handling and arbitration, ensuring efficient and reliable communication between devices.

Mechanical and Electrical Characteristics

The VMEbus uses a 96-pin connector for electrical connections, with specific pins designated for power, ground, data, address, and control signals. The bus operates at a voltage of 5V, with optional support for 3.3V devices. The mechanical design of the VMEbus ensures robust connections and reliable operation in harsh environments.

Applications

VMEbus is used in a wide range of applications, including industrial automation, telecommunications, data acquisition, and military systems. Its flexibility and scalability make it suitable for both small and large systems, and its robustness ensures reliable operation in demanding environments.

Related Technologies

VMEbus has inspired the development of several related technologies, including VXIbus, which is used for automated test equipment, and VPX, which is designed for high-performance computing applications. These technologies build on the foundation of VMEbus, offering enhanced features and capabilities for specific applications.

See Also

• Motorola 68000
• VXIbus
• VPX
• IEEE 1014-1987
• Eurocard