Futurebus

Futurebus, or 'IEEE 896, is a computer bus standard, intended to replace all local bus connections in a computer, including the CPU, memory, plug-in cards and even, to some extent, LAN links between machines. The effort started in 1979 and didn't complete until 1987, and then immediately went into a redesign that lasted until 1994. By this point, implementation of a chip-set based on the standard lacked industry leadership. It has seen little real-world use, although custom implementations continue to be designed and used throughout industry. Futurebus, or 'IEEE 896, is a computer bus standard, intended to replace all local bus connections in a computer, including the CPU, memory, plug-in cards and even, to some extent, LAN links between machines. The effort started in 1979 and didn't complete until 1987, and then immediately went into a redesign that lasted until 1994. By this point, implementation of a chip-set based on the standard lacked industry leadership. It has seen little real-world use, although custom implementations continue to be designed and used throughout industry. In the late 1970s, VMEbus was faster than the parts plugged into it. It was quite reasonable to connect a CPU and RAM to VME on separate cards to build a computer. However, as the speed of the CPUs and RAM rapidly increased, VME was quickly overwhelmed. Increasing the speed of VME was not easy, because all of the parts plugged into it would have to be able to support these faster speeds as well. Futurebus looked to fix these problems and create a successor to systems like VMEbus with a system that could grow in speed without affecting existing devices. In order to do this the primary technology of Futurebus was built using asynchronous links, allowing the devices plugged into it to talk at whatever speed they wished. Another problem that needed to be addressed was the ability to have several cards in the system as 'masters', allowing Futurebus to build multiprocessor machines. This required some form of 'distributed arbitration' to allow the various cards to gain access to the bus at any point, as opposed to VME, which put a single master in slot 0 with overall control. In order to have a clear performance benefit, Futurebus was designed to have the performance needed ten years in the future. Typical IEEE standards start with a company building a device, and then submitting it to the IEEE for the standardization effort. In the case of Futurebus this was reversed, the whole system was being designed during the standardization effort. This proved to be its downfall. As companies came to see Futurebus as the system, they all joined in. Soon the standards meetings had hundreds of people attending, all of them demanding that their particular needs and wants be included. As the complexity grew, the standards process slowed. In the end it took eight long years before the specification was finally agreed on in 1987. Tektronix did make a few workstations based on Futurebus. American Logic Machines (ALM) continues to build end to end system Futurebus hybrid solutions, including VME-to-Futurebus+ and other Bus-to-Futurebus bridge technologies. That was just in time for the US Navy who had been looking for a new high-speed system for the Next Generation Computer Resources (NGCR) project for passing sonar data around in their newly designed Seawolf-class submarines, and they said they would standardize on Futurebus if only a few more changes would be made. Seeing a potential massive government buy, the additions effort started immediately on Futurebus+. It took another four years for the Futurebus+ Standard to be released by this time custom variation of Futurebus took the lead in industry.