FASTBUS facts for kids

FASTBUS (also known as IEEE 960) is a special kind of computer bus. Think of a computer bus as a super-fast highway inside a computer that helps different parts talk to each other. FASTBUS was made to handle lots of information very quickly. It was often used in big science projects, especially in particle detectors, which are machines that help scientists study tiny particles. It's also a standard for how electronic parts fit together in special boxes called "crates."

How FASTBUS Systems Work

A FASTBUS system is made up of different parts called "segments." These segments can be "crate segments" or "cable segments." They are connected using something called a segment interconnect.

Crate Segments Explained

A crate segment is like a big electronic box that fits into a 19-inch rack. Inside this box, there's a special board called a backplane. This backplane has slots where you can plug in up to 26 electronic parts, called "modules."

• Each module is usually a circuit board with a front panel.
• Modules are about 14 inches by 15 inches in size.
• They can take up one or more slots in the crate.

Smaller FASTBUS systems might just use one crate or a few crates connected directly to a main computer.

Cable Segments and Connections

Cable segments use special cables that are 32 bits wide. This means they can send a lot of information at once. These cables use a special way of sending signals to make sure data travels fast and reliably.

How Modules Talk to Each Other

In a FASTBUS system, modules can be either a "master" or a "slave."

• A master module is like a leader. It controls the bus and tells other modules when to send or receive data.
• A slave module is like a follower. It responds to commands from a master.

Many master modules can be in one segment. They take turns controlling the bus. This allows for very fast reading of data from all modules in a segment, one after another, without needing a central computer to manage every step.

Physical Design of FASTBUS

FASTBUS crates are quite tall compared to other electronic crates. The power supply for a FASTBUS crate is usually placed below the crate itself. This means it takes up even more space in a rack.

Power and Cooling Needs

Full-sized FASTBUS crates can hold 26 modules. Each module can use a lot of power, up to 70 watts! This means a full crate can produce a lot of heat, about 1750 watts.

• Modules need different power supplies, like -5.2 volts and +5 volts.
• Crates often have very powerful power supplies (200 or 300 amps) to provide enough electricity.
• Because of all the heat, keeping the system cool is a big challenge. Large installations need special cooling and air handling systems.

History of FASTBUS

FASTBUS was created to replace an older system called CAMAC. CAMAC had some limitations:

• It was slow.
• It could only send a limited amount of data at once.
• It had only one main controller.
• Connecting different crates was difficult.

FASTBUS aimed to fix these problems by being much faster and allowing many parts to work together. It used a special "asynchronous" way of sending data, meaning parts didn't have to wait for a clock signal to communicate.

The official standard for FASTBUS was approved in May 1984.

Where FASTBUS Was Used

During the 1980s, FASTBUS was used in many important high-energy physics experiments. These experiments took place at major science laboratories around the world, including:

• CERN
• SLAC
• Fermilab
• Brookhaven National Laboratory
• TRIUMF

Today, FASTBUS has mostly been replaced by newer technologies like VMEbus for smaller systems. For very large systems, custom-made designs are often used because they can be cheaper for each connection.

Challenges with FASTBUS

Some parts of FASTBUS, like the cable segments, were not used as much as expected. This was partly because it was hard to make the special chips needed for them. Also, the cables themselves were wide and difficult to handle. The parts that connected different segments were also complex and expensive. These challenges meant that the full potential of the FASTBUS system was not always reached.

FASTBUS Standards

The details of FASTBUS are described in a document called IEEE standard 960-1986. This standard is titled "IEEE Standard FASTBUS Modular High-Speed Data Acquisition and Control System."

The system was first developed by a group called the NIM committee in the US Department of Energy. Scientists from European and Canadian laboratories also helped create this important standard.