▁value ▁of ▁the ▁file ▁name ▁is ▁derived ▁for ▁each ▁file ▁and ▁stored ▁in ▁the ▁directory ▁record . ▁When ▁searching ▁for ▁a ▁file , ▁the ▁file ▁name ▁is ▁first ▁converted ▁to ▁upper ▁case ▁using ▁the ▁up case ▁table ▁( file ▁names ▁are ▁case ▁ins ens itive ) ▁and ▁then ▁hash ed ▁using ▁a ▁propriet ary ▁pat ented ▁algorithm ▁into ▁a ▁ 1 6 - bit ▁( 2 ▁byte ) ▁hash ▁value . ▁Each ▁record ▁in ▁the ▁directory ▁is ▁searched ▁by ▁comparing ▁the ▁hash ▁value . ▁When ▁a ▁match ▁is ▁found , ▁the ▁file ▁names ▁are ▁compared ▁to ▁ensure ▁that ▁the ▁proper ▁file ▁was ▁located ▁in ▁case ▁of ▁hash ▁coll isions . ▁This ▁impro ves ▁performance ▁because ▁only ▁ 2 ▁bytes ▁have ▁to ▁be ▁compared ▁for ▁each ▁file . ▁This ▁significantly ▁reduces ▁the ▁CPU ▁cycles ▁because ▁most ▁file ▁names ▁are ▁more ▁than ▁ 2 ▁characters ▁( bytes ) ▁in ▁size ▁and ▁virt ually ▁every ▁comparison ▁is ▁performed ▁on ▁only ▁ 2 ▁bytes ▁at ▁a ▁time ▁until ▁the ▁intended ▁file ▁is ▁located . ▁ ▁Met adata ▁and ▁check sum s ▁ ▁ex F AT ▁introdu ces ▁metadata ▁integrity ▁through ▁the ▁use ▁of ▁check sum s . ▁There ▁are ▁three ▁check sum s ▁currently ▁in ▁use . ▁The ▁Volume ▁Boot ▁Record ▁( V BR ) ▁is ▁a ▁ 1 2 ▁sector ▁region ▁that ▁contains ▁the ▁boot ▁records , ▁B IOS ▁Parameter ▁Block ▁( B P B ), ▁O EM ▁parameters ▁and ▁the ▁check sum ▁sector . ▁( There ▁are ▁two ▁V BR ▁type ▁regions , ▁the ▁main