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Building & Buying a PC

Volume I, Issue No.10 JULY 19, 1995


DOS utilizes varying size clusters depending on the size of thepartitions selected when formatting a hard drive. Thelarger the partition-the larger the cluster; as follows:

Partition Size Clusters

Up to 16 MB 1 KB

> 16 - 128 MB 2 KB

>1 28 - 256 MB 4 KB

>256 - 512 MB 8 KB

>512 - 1024 MB 16 KB

> 1 GB and Up 32 KB

Cluster size is important! It establishes the smallest possibledisk space to be taken up by a file.

While a file may only show 150 bytes, it will occupy the amountof disk space determined by cluster size; from 1 KB to 32 KB.Three 150 byte files would actually occupy a minimum of 3 KB (3x 1 KB) up to a maximum of 96 KB (3 x 32 MB), depending on partitionsize set up. Hard drives occasionally indicate they are full whentotal bytes on a drive will appear a long way from being full.HD fullness depends on occupied clusters, not total bytes stored.

Therefore, in determining partition size to set up on your harddrive, consideration must be given to the anticipated file sizeto be used by the programs on your HD. If you utilize many smallfiles, then use smaller clusters. If you utilize many large files,(as in CAD or video programs) use larger size clusters.

There are tradeoffs between the extreme ends of the spectrum.Partition sizes in the 190 MB range will probably suffice forthe average user.

A 540 MB hard drive could be formatted for 190 MB as C: drive,190 MB as D: drive, and the remaining 160 MB as E: drive. Manypossibilities abound! Or, a user might prefer one physicalHard Drive with two partitions, such as-C:\ 270 megs. & D:\270 megs. Or, one physical Hard Drive, all as one partition of540 megs. The numbers are approximate depending on what softwarewe use. Some apps. define 1 meg as 1,000,000 bytes. While otherapps see 1 meg as 1,240,000 bytes (1024K).

When dealing with Hard Drives of 540 megs or greater, other variablesmust be taken into consideration. What is the total capacity ofthe hard drive? Is the hard drive IDE or EIDE? For a 1.2 GigabyteHard Drive, we might prefer a HD with equal partition sizes of256 megs. (). This material only covers one aspect of the equation.

For more details see the Electronic Computer Dictionary ondisk!


byte-holds the equivalent of a single character, such asthe letter A, a dollar sign or decimal point. For numbers, a bytecan hold a single decimal digit (0 to 9), two numeric digits (packeddecimal) or a number from 0 to 255 (binary numbers).

Kilobyte - One thousand bytes. (KB, Kbyte and K-byte)

megabyte - One million bytes. (MB, Mbyte and M-byte)

gigabyte - One billion bytes. (GB, Gbyte and G-byte)

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