This means that the only operating system on the computer is "DOS" if it's an older machine, you will purchase a copy of some form of software such as windows that will be able to run on it. depending on how old the laptop is... flip the laptop over and take a look for a microsoft windows registration sticker. if it has one, whoever sold it to you is legally obliged to give you the copy of windows that it was shipped with... if you do not have a windows sticker. you will need to install a new operating system onto the computer. if either of these is not an option, a person may be able to look into linux, or other free operating system
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