ZIP DISKS

3/21/98

ZIP disks: "ZIP" Disks are very high capacity Floppy Disks with capacities in the 25 to 250 mb range. Five formats are in common use -- A 100mb ZIP format, a 120 mb LS120 format, 135 EZFlyer, a 230mb EZFlyer, and a 250mb ZIP. Except for the rarely seen 25mb ZIP which can be read and written in the same drive as the 100mb, the media are not interchangeable.

As of 1998, ZIP drives cost roughly 3 to 6 times the price of a floppy drive. Media costs are roughly 10 cents an uncompressed megabyte as compared to 17 cents for floppy, 1 cent for hard drives, and 1 cent or less for tape.

The drives are available with SCSI, IDE and Parallel port interfaces although not all interfaces are available for all formats. Disk formats and low level tools are media specific and depend on utilities provided by the manufacturer. Data on the number of tracks and cylinders appear to be proprietary. Typical specifications include rotation speeds of about 3000 rpm, seek times of about 30mSec and sustained transfer rates of about 1MegaByte/Sec. Actual data rates depend on the drive and interface 150KByte/Sec for parallel, 500KiloByte/Sec for EIDE or SCSI -- give or take a factor of 2 or 3. MTBFs are quoted at 100,000 hours or more with error rates of about 1 part in 10^12.

Power (for ZIP) is 5 watts typical, 8.5 watts peak.

Note that published specifications are in terms of "MB/Sec" which appears to be an abbreviation for "Optimistic MegaBytes/Sec". PC Magazine tests of Iomega ZIP drives (12Mar96) showed about 455KBytes per second transfer rates for SCSI ZIP and 120KBytes/Sec for parallel. Iomega claims 60 "MB"/Min (1000 KByte/Sec) and 25 "MB/Min (416 KBytes/Sec) respectively.

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