Learn about the technologies behind the Internet with The TCP/IP Guide!
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.
View over 750 of my fine art photos any time for free at DesktopScenes.com!

[ The PC Guide | Systems and Components Reference Guide | Hard Disk Drives | Hard Disk BIOS and Capacity Factors | Hard Disk BIOS Translation Modes ]

Normal / Standard CHS Mode

The normal or default mode used by "regular" hard disks that are below 504 MiB in size is called variously Normal or CHS mode, where "CHS" stands for "cylinder, head, sector", the three parameters used in hard disk geometry specifications. In this mode, there is no translation done at the BIOS level, and the logical geometry presented by the disk is used by the BIOS directly. Remember that this is still logical geometry. The actual physical geometry is known only to the disk controller.

Each hard disk using CHS mode is limited to 1,024 cylinders, 16 heads and 63 sectors, or 504 binary megabytes. This is also the only mode available on older BIOSes, from before about 1994. When hard disks above 504 MiB in size are used with one of these older BIOSes, the infamous 504 MiB barrier is hit.

Next: Extended CHS (ECHS) / Large Mode


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