All computers need some sort of(71)(OS). Tile majority of modem home computers use some form. of Microsofts OS. The original Microsoft OS was called DOS though most computers use Windows. Windows comes in various versions beginning with(72)x then 95, 98, ME and currently XP. A few computers use IBMs O/SApples Mac uses their own OS beginning with OS I though most modem Macs use version x or x. Apples latest version is OS 10.x. In the past large companies and institutions would have an OS design exclusively for them but as the Commercial OS become more sophisticated the benefits of this practice is becoming less apparent. Some computer professionals,(73)(ISP)and(74)computer users use an OS such as UNIX(or a variant such as Linux), Windows NT or 2000(Win2k)or one of the other network or(75)based OS.