Studying for the A+, Network+ or Security+ exams? Get over 2,600 pages of FREE study guides at CertiGuide.com!
Join the PC homebuilding revolution! Read the all-new, FREE 200-page online guide: How to Build Your Own PC!
NOTE: Using robot software to mass-download the site degrades the server and is prohibited. See here for more.
Find The PC Guide helpful? Please consider a donation to The PC Guide Tip Jar. Visa/MC/Paypal accepted.
Take a virtual vacation any time at DesktopScenes.com - view my art photos online for FREE in either Flash or HTML!

[ The PC Guide | Systems and Components Reference Guide | Motherboard and System Devices | System BIOS | BIOS Settings | IDE Device Setup / Autodetection ]

Cylinders

The number of cylinders on each side of each platter in the disk. For older drives, this is the number of physical cylinders the disk uses. For newer disks, it is the logical number of cylinders that the drive specifies for use in the BIOS setup; see here for an explanation of physical and logical geometry.

For newer drives using BIOS geometry translation, the BIOS reduces the number of logical cylinders by dividing it by an integer factor (2, 4, etc.) so that it is less than 1,024 (the BIOS limit for the number of cylinders for historical reasons) and then multiplies the number of heads by the same number.

For example, a Western Digital Caviar 33100 3.1 GB drive has nominal parameters (logical geometry) of 6,136 cylinders, 16 heads and 63 sectors. When you set up this drive (autodetect it) most BIOSes will record 767 cylinders, 128 heads and 63 sectors. Of course the drive doesn't really have only 767 cylinders, but this is the way that the BIOS gets around the infamous 504 MB restriction. See here for more details on BIOS translation.

Note: Some BIOSes will continue to show the actual physical parameters even when set to a translating mode like LBA. This can be confusing to see on the screen, but if the BIOS is set to "LBA" or "Large", it should be using the translated parameters internally.

Note: IDE autodetection will set this value automatically.

Next: Heads


Home  -  Search  -  Topics  -  Up

The PC Guide (http://www.PCGuide.com)
Site Version: 2.2.0 - Version Date: April 17, 2001
Copyright 1997-2004 Charles M. Kozierok. All Rights Reserved.

Not responsible for any loss resulting from the use of this site.
Please read the Site Guide before using this material.
Custom Search