Original sentence: A variety of other barriers have existed, usually due to device drivers and disk I/O layers in operating systems that did not correspond with ATA standards.However, DMA (and later Ultra DMA, or UDMA) greatly reduced the amount of processing time the CPU had to use in order to read and write the disks by allowing the disk controller to write data to memory directly, thus bypassing the CPU
Edited sentence: A variety of other barriers have existed, usually due to poorly-written device drivers and disk I/O layers in operating systems.Even the barriers listed above mostly came about due to poor BIOS implementations.However, DMA (and later Ultra DMA or UDMA) greatly reduced the amount of processing time the CPU had to use in order to read and write the disks by allowing the disk controller to write data to memory directly, thus bypassing the CPU.However, such an excuse is not really possible for the 32GB and 137GB limit.In fairness, hard drive sizes progressed very slowly from 1GB–8GB, with companies marketing drive models that differ in size by only 100MB.It was therefore not unreasonable to think that the 8GB limit would not be exceeded in the useful life of a controller