re ide vs scsi in article apr julian uwo ca wlsmith valve heart rri uwo ca wayne smith writes stuff deleted so the lowly low density original pc fdd card used dma and the pc at hdd controller doesn t that makes real sense actually it does make a reasonable amount of sense fixed disk sectors are buffered by the controller and transferring them to memory with a rep insw or whatever the instruction is called is quite efficient single instruction goes as fast as the controller cpu know how to use the bus since the wasn t cached the bus is likely a critical resource relative to cpu performance and it s possible that dma bus interference would cause as much or more loss of cpu cycles for computing as does the rep insw sequence the floppy on the other hand is not buffered so that using the cpu for floppy data transfer as was done on the pc jr by the way really does stink wally bass
