Editing Direct-access storage device (section)

===FBA===
In 1979 IBM introduced [[fixed-block architecture]] (FBA) for mainframes. At the programming level, these devices do not use the traditional CHR addressing, but reference fixed-length blocks by number, much like sectors in mini-computers. More correctly, the application programmer remains unaware of the underlying storage arrangement, which stores the data in fixed physical block lengths of 512, 1024, 2048, or 4096, depending on the device type. As part of the FBA interface IBM introduced new channel commands for asynchronous operation that are very similar to those introduced for ECKD.
 
For some applications, FBA not only offers simplicity, but an increase in throughput.

FBA is supported by [[VM (operating system)|VM/370]] and [[VSE (operating system)|DOS/VSE]], but not [[MVS]]{{efn|However, the privileged routine IOSFBA provides limited access to these devices.}} or successor operating systems in the OS/360 line.