Page "Bus (computing)" Paragraph 15

High-end systems introduced the idea of channel controllers, which were essentially small computers dedicated to handing the input and output of a given bus.

IBM introduced these on the IBM 709 in 1958, and they became a common feature of their platforms.

Other high-performance vendors like Control Data Corporation implemented similar designs.

Generally, the channel controllers would do their best to run all of the bus operations internally, moving data when the CPU was known to be busy elsewhere if possible, and only using interrupts when necessary.

This greatly reduced CPU load, and provided better overall system performance.