ANSI introduced SCSI-2 as early as 1990, but after several changes it was not standardized until 1994 as X3.131-1994. The Common Command Set( CCS) was one of the most important prerequisites for the standardization of SCSI-2.
SCSI-2 represents a significant improvement over SCSI-1 with a more comprehensive command set and several new features. The increase of the clock frequency to 10 MHz and the resulting data transfer rate of 10 MB/s with an 8-bit bus should be mentioned. In the 16-bit version, the Wide-SCSI, the data transfer rate is 20 MB/s. In addition, 16 drives can be connected to SCSI-2, the SCSI bus can be actively terminated and the length of the SCSI cable, which is only 3 m, can be increased by transmitting differential signals. This transmission technique was subsequently named High Voltage Differential( HVD) after Low Voltage Differential( LVD) was introduced in Ultra-SCSI.