A computer system has a system memory, a central processing unit, an input/output controller, and at least one device. When the central processing unit wants data transferred to/from system memory from/to the device, it sends Indirect DAta Address Word (IDAW) commands to the I/O controller. Instead of performing a direct memory access (DMA) operation for each IDAW command, the I/O controller starts an IDAW look ahead procedure. In this procedure, the I/O controller checks to see if the system addresses of the system memory specified in the IDAW commands are contiguous. If so, the procedure combines IDAWs that specify contiguous system addresses up to the maximum DMA transfer length. Using this procedure, the number of DMA operations sent to the system memory is minimized, and the computer system has more efficient data transfer operations.