SHCC WYSIWYG Article from May 2011

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This article was written by Don VanSyckel, the club president, as a part of "The President's Pen".  This article appeared in the May 2011 WYSIWYG newsletter.

Hard Drive Explosion

by Don VanSyckel

Here's something to think about, just a year or two ago laptops were selling with 40 and 60 Gbyte hard disks. Today I can go to the computer store and buy a 64 Gbyte thumb drive off the shelf. Granted the 64 Gbyte model costs a premium price per Gbyte than the 4 and 8 Gbyte models, but this is to be expected. At this point you're probably thinking, yea, but thumb drives are so slow compared to a real hard drive. You should not compare a thumb drive using the USB interface with an internal hard disk. Comparing a USB thumb drive to an external USB hard drive would be a more fair comparison.

Some companies have taken the memory chip technology used in thumb drives and built storage units that use the ATA or SATA interface that typical hard disks use. These units function exactly the way the standard hard disk does but there are no moving parts. This also means that all data is equally available at all times. These units are sometimes called solid state disk.

In a hard drive a read / write head is used to read and write data from and to the disk. The hard disk is laid out in tracks which are concentric circles on the surface of the hard drive platters. Then marks are written in the track to mark blocks of space called sectors. There will be one read / write head for each platter surface. To save money and space the heads for the various platter surfaces are built into one assembly so there needs to be only one motor and one control circuit. As a file is read or written the head assembly must be moved to the track to first access. Once the head is positioned it has to read some from the track to determine if it's at the correct track and to locate the particular sector for reading or writing. The time to move the head from place to place and acquire the initial track location read is generally called the seek time. Seek time is shortened if the disk spins faster that's why disk have advanced from 5400 RPM to 7200 RPM to 10,000 RPM.

In a solid state disk nothing moves so there is no time wasted positioning hardware. The memory is simply read or written. The technology needed in solid state disks is different than that used in main PC memory and is slower in reading and writing. Remember the 1 or 2 Gbytes of main PC memory can cost more that the 32 or 64 Gbyte thumb drive. Another advantage of solid state disks is they could be made smaller. Today they are built in a size to be compatible with today's hard drives or they could not be used. Disk drives used to be 18" or more and come in a stand alone cabinet, then down to 8", then down to 5.25", and now down to 3.5".

I predict that within a few years there will be another standard disk size evolve for solid state drives. There might even be adapters sized for the 3.5" hard disk slots which mount the new solid state drive.

End of Article

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