byte(s)   description

     0-3       far pointer to device header of next device driver, 
               set by MS-DOS when the driver is installed
     4-5       attribute word
     6-7       offset from beginning of file to "strategy" entry
     8-9       offset from beginning of file to "interrupt" entry
     10        first character of name of character device, or the 
               number of units of a block device
     11-17     last seven characters of name of character device