A version of the SCSI command specification. SCSI-2 shares the ORiginal SCSI' s asynchronous and synchronous modes and adds a "Fast SCSI" mode (<10MB/s) and "Wide SCSI" (16 bit, <20MB/s OR rarely 32 bit). Another majOR enhancement was the definition of command sets fOR different device classes. SCSI-1 was rather minimalistic in this respect which led to various incompatibilities especially fOR devices other than hard-disks. SCSI-2 addresses that problem. allowing scanners, {hard disk drive}s, {CD-ROM} drives, tapes and many other devices to be connected. NORmal SCSI-2 equipment (not wide ORdifferential) can be connected to a SCSI-1 bus and vice versa. (1995-04-19)