and impacts that would damage other tape formats. However, because the tape is belt-driven, seeking back and forth can eventually cause the tape to become unevenly tensioned. It is therefore necessary to periodically retension the cartridge. This is accomplished by winding the tape from beginning to end and back in one operation, allowing the belt to equalize itself. For newer QIC drives that use a SCSI interface, there is a SCSI "RETENSION" command to do this. When the cartridge gets old, the belt may not provide enough friction to turn the takeup spool smoothly. When this happens, the tape will need to be replaced. In some cases a cartridge must be formatted before use. The capability to do this is in the drive rather than the host computer. Generations 3M Data Cartridge (DC) The first QIC tape format was the by Data Cartridge (DC) format with two internal belt-driven reels and a metal base. The original product, the DC300, has 300 feet of tape and holds 200 kilobytes. Various QIC DC recording formats have appeared over the years, including: QIC-11: a four-track format giving 20 MB on a 450 ft DC300XL cartridge QIC-24: nine-track, 45 MB or 60 MB on a 450 or 600 ft DC600A cartridge, respectively QIC-120: 15-track, 125 MB, DC6150 cartridge QIC-150: 18-track, 150 MB, DC6150 cartridge QIC-525: 26-track, 525 MB on a 1020 ft DC6525 cartridge QIC-1350: 30-track, 1.35 GB on a DC9135 cartridge Other QIC DC standards include the QIC-02 and QIC-36 drive interface standards. Later QIC DC drives usually use the QIC-104/111 SCSI and QIC-121 SCSI-2 interfaces. Other Data Cartridge (DC) look-alikes: 3M DC600HC, a preformatted tape with 16 tracks on 600 foot DC600A and software-based EOT/BOT detection. HP used these in the HP914x type of cartridge drives. QIC Mini Cartridge (MC) Later, the smaller Minicartridge (MC) form-factor was introduced. This is by size and is small enough to fit in a drive bay. QIC-40 20-track DC2000 mini-cartridge 205 ft. 40 MB 20-track DC2000XL mini-cartridge 307½ ft. 60 MB QIC-80 28-track DC2080 mini-cartridge 205 ft. 80 MB 28-track DC2120 mini-cartridge 307½ ft. 120 MB The QIC-40 and QIC-80 were designed to use the same floppy disk controller as a standard floppy drive, with MFM or RLL encoding. Travan (TR) Travan is an evolution of the QIC Minicartridge format, sold for personal computer use. This version, developed by 3M, uses a longer and wider (8