The DOS manual :  disk operating system. 

 - Cupertino, Calif. :  Apple Computer Inc.,  1981. 
 - 200 p. :  ill. ;  22 cm. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Operating systems (Computers)
<br/><br/><label>Dewey Class. No.: </label>005.43