Most CD-ROM drives are now of this EIDE type design and share the hard drive cable. More information on the SCSI interface will be added shortly. Size Limitations - IDE drives have BIOS and INT13 combined limitations. There is a limitation at the 504MB size, the 2GB size, the 4GB and 8.4GB sizes. In AT type computers, the floppy and hard drive cables have different twists and should not be interchanged.
Floppy cable has seven twisted lines.
Floppy cables have the twists in the lower pin numbers. The bus it is attached to must be terminated at two ends. Terminators are found close to the connector slot on the SCSI device. Terminators can a set of three resistors or on newer devices the termination might be built-in and switched ON or OFF by using switches. IDE uses a 40-pin cable with a maximum length of 18 inches.