Determining Fixed Disk Size from Physical Parameters (78920)

This article was previously published under Q78920


If the physical characteristics of a fixed disk are known, it is possible to calculate the size of the disk in megabytes. The following information is needed to make the determination:
Cylinders      (CYL)    (Physical number of cylinders [tracks])

Heads          (HDS)    (Physical number of read/write heads)

Sectors/Track  (SPT)    (Logical number of sectors per track)

Bytes/Sector   (BTS)    (Usually 512 for MS-DOS systems; other
                         values may apply for OEM and/or third
                         party partition schemes.)
Given the above information, the size of the fixed disk in megabytes may be calculated as follows:

[(CYL)*(HDS)*(SPT)*(BTS)]/[(1024)*(1024)] = size in megabytes

The physical characteristics of a fixed disk may be determined in some cases by using the system setup program provided by the system manufacturer, or by contacting the fixed disk manufacturer.

Modification Type: Major Last Reviewed: 7/30/2001
Keywords: KB78920