Simplify the following text for a Grade 8 native English-speaking person.
Original: In 1988 , the different types of RAID ( 1 to 5 ) , were written about by David Patterson , Garth Gibson and Randy Katz in their article , called `` A Case for Redundant Arrays of Inexpensive Disks ( RAID ) '' .
Simplified: The term RAID was first defined by David A. Patterson , Garth A. Gibson and Randy Katz at the University of California , Berkeley , in 1987 . They studied the possibility of using two or more drives to appear as a single device to the host system and published a paper : `` A Case for Redundant Arrays of Inexpensive Disks ( RAID ) '' in June 1988 at the SIGMOD conference .