Overview
IEC 60796-1:1990 - "Microprocessor system bus - 8-bit and 16-bit data (MULTIBUS I) - Part 1: Functional description with electrical and timing specifications" - is a foundational international standard developed by the International Electrotechnical Commission (IEC) and referenced by ISO. It specifies the functional, electrical, and timing requirements for the MULTIBUS I microprocessor system bus, supporting both 8-bit and 16-bit data paths.
This standard facilitates interoperability among data processing, storage, and peripheral control devices within microprocessor systems. By defining a common interface bus, IEC 60796-1 enables parallel signal and data transfers between modules, supporting complex, closely coupled computing environments.
Key Topics
- Bus Architecture: Based on the master-slave concept, where the master device initiates transfers and the slave device responds upon address recognition.
- Address Spaces: Provides two independent spaces: memory (24-bit addressing enabling up to 16 MB) and I/O (16-bit addressing for up to 64K I/O ports).
- Data Transfers: Details mechanisms for both 8-bit and 16-bit data transfer cycles, covering input/output and memory operations.
- Signal Definitions: Standardizes control lines, address lines, data lines, and interrupt lines, with consistent notation focusing on electrical "High" and "Low" states.
- Multiple Masters Support: Enables multiprocessing configurations via serial or parallel bus arbitration, allowing resource sharing among multiple master modules.
- Electrical and Timing Specifications: Outlines requirements for signal voltages, timing cycles, and bus arbitration to ensure reliable, high-speed operation (up to 5 million transfers per second).
- Compliance Levels: Defines varying levels of bus compliance to support a wide range of device capabilities and ensure product compatibility.
Applications
IEC 60796-1 is primarily used in the design, evaluation, and implementation of hardware that needs to interface via the MULTIBUS I system bus, including:
- Microprocessor Boards: Ensuring compatible communication between different processing units and peripheral controllers.
- Embedded Systems: Facilitating reliable connections among closely integrated system modules.
- Multiprocessing Configurations: Supporting systems requiring multiple masters and high-speed parallel processing.
- Industrial Automation: Used in measurement, control, and logic devices where robust data transfer and interoperability are crucial.
- Retrofit and Maintenance: Useful for maintaining or updating legacy systems built on the MULTIBUS I architecture.
By adhering to this standard, manufacturers and system integrators guarantee that their products can seamlessly communicate and interoperate, reducing custom engineering, increasing reliability, and fostering a broader ecosystem of compatible components.
Related Standards
For those implementing MULTIBUS I or designing systems with parallel data buses, these related standards provide further guidance:
- IEC 60796-2: Covers mechanical and connector specifications for the MULTIBUS I system bus, detailing edge connector configurations.
- IEC 60796-3: Addresses mechanical and pin descriptions for the Eurocard (indirect) configuration.
- IEC 60050: Provides international electrotechnical vocabulary for consistent terminology.
- IEC 60027, IEC 60417, and IEC 60617: Standardize letter symbols, graphical symbols for equipment, and diagram representation, respectively.
- IEC 625-1: Defines interface systems for programmable measuring instruments, cited as a reference for terminology and system concepts in IEC 60796-1.
Keywords: microprocessor system bus, MULTIBUS I, IEC 60796-1, 8-bit data bus, 16-bit data bus, electrical specifications, timing specifications, master-slave architecture, memory addressing, I/O addressing, system interoperability, parallel data transfer, bus arbitration.