Ultra wide SCSI interfaces offers faster data transmission rates of up to 80 and 160 megabytes per second as compared to the standard serial and parallel ports.
8-BIT SCSI: In this type the data transfer rate was only 5 MBps and its cable length was 6 feet. This narrow SCSI interface has 50 pins.
16-BIT SCSI: The latest SCSI standard, Ultra-2 SCSI for a 16-bit bus has the capability to transfer data at up to 80 megabytes per second. In Ultra-2 SCSI up to 15 devices can be attached in a daisy chain fashion to one SCSI port or card. These devices have a unique ID that supports one IRQ. Ultra2 and Ultra3 SCSI cables have the capability to extend up to 12 feet. This SCSI interface has 68 pins.
SCSI FAST is referred to transfer rates of 10 MB/Sec with a narrow device, and a transfer rate of 20 MB/Sec for a Wide/Fast device. Some of the SCSIFAST Types are:
SCSI FAST-20 - Transfer rates of 20 MB/Sec with a narrow device, and 40 MB/Sec for a ULTRA / Wide / Fast device.
SCSI Fast-40 - Transfer rates of 40 MB/Sec with a narrow device, and 80 MB/Sec for a wide device.
SCSI Fast-80 - Transfer rates of 80 MB/Sec with a narrow device, and 160 MB/Sec for a wide device.
