The double-density drive of the Plus 3 was driven using a WD1770 drive controller by the ADFS. (The Plus 3 had been rumoured to offer Acorn's DFS and to feature a 8272 double density disk controller before its launch.) Because the WD1770 is capable of single density mode and uses the same IBM360 derived floppy disc format as the Intel 8271 found in the BBC Micro, it was also possible to use the Disc Filing System with an alternate ROM, such as the ACP 1770 DFS.