1394a

1394a is an amendment to the IEEE 1394 standard, part of the FireWire family of high-speed serial bus interfaces. Ratified in 2000 as IEEE Std 1394a-2000, it preserves the 400 Mbit/s data rate of the original 1394 specification while introducing enhancements intended to simplify implementation and improve interoperability among devices and hosts.

The amendment provides improvements to the electrical and protocol layers to support easier design and more flexible use of the bus. It maintains backward compatibility with earlier 1394 devices, meaning devices and hosts that support 1394a can typically interoperate with 1394 devices without requiring a new controller. 1394a also emphasizes more robust bus management and smoother handling of device discovery and connection changes, which is beneficial for consumer electronics and storage peripherals that rely on FireWire connections.

In practice, 1394a helped standardize and streamline FireWire implementations across hardware from cameras to external drives, contributing to wider adoption during the early to mid-2000s. Over time, many devices shifted to newer speeds such as 1394b (800 Mbit/s) or to USB-based interfaces, but 1394a remains part of the historical lineage of FireWire technology, preserving compatibility with existing 400 Mbit/s FireWire ecosystems.

See also: IEEE 1394, FireWire, 1394b.