Conclusions

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• Hard disks: Very fast and with more capacity than floppy disks, but also more expensive. Some hard disk systems are portable (removable cartridges), but most are not.
• Floppy disks: Relatively slow and have a small capacity, but they are portable, inexpensive, and universal.
• Magnetic tapes: Relatively inexpensive and can have very large storage capacities, but they do not permit random access of data.
• Optical disks: Optical disks have very large storage capacity, but they are not as fast as hard disks. In addition, the inexpensive optical disk drives are read-only. Read/write varieties are expensive.

	Cost of Drive	Capacity (GB)	Transfer Rate (MB/sec)	Unit Media Cost	Cost/GB for media	# Needed for 20 GB
CD-R	$200	0.65	1.2 (8x unit)	$1.50	$2.31	31
CD-R/W	$250	0.65	1.2 (8x unit)	$4	$6.15	31
DVD-R (4.7GB)	$5,400	4.7	1.4	$45	$9.57	4
DVD-R (3.95 GB)	$5,400	3.95	1.4	$40	$10.13	5
DVD-RAM (single)	$500	2.6	1.4	$30	$11.54	8
DVD-RAM (double)	$500	5.2	1.4	$40	$7.69	4
DLT-IV (Digital Linear Tape)	$2,000+	20	1.5	$70	$3.50	1
Magnetic Disk	$160 – $1,000	20	5 – 40	*	$8 – $50	1
Jaz†	$300	2	4.9 – 8.7	$100	$50	10
Zip‡	$150	0.25	.8 – 2.4	$15	$60	80

^†Jaz: Both Jaz and Zip drives are a removable disk drive developed by Iomega Corporation. The Jaz drive has a 12-msec average seek time and a transfer rate of 5.5 Mbps. The removable cartridges hold up to 2 GB of data. The fast data rates and large storage capacity make it a viable alternative for backup storage as well as everyday use.

^‡Zip: A Zip drive takes removable 100 megabyte hard disks. Both internal and external drives are manufactured, making the drive suitable for backup, mass storage or for moving files between computers.