Dell OptiPlex E1 - Manual (Page 7)

DMA Channel Assignments: Dell™ OptiPlex™ E1 Systems
DREQ Line Used By/Available
DREQ0 Available
DREQ1 Available
DREQ2 Super I/O controller (to initiate DMA cycle for attached
diskette drive)
DREQ3 Available
DREQ4 Bus controller chip (to activate second DMA controller)
DREQ5 Available
DREQ6 Available
DREQ7 Available
NOTE: The integrated sound controller, NIC, and video controllers are assigned available DMA channels automatically during system start-up.