re ide vs scsi richk grebyn com richard krehbiel writes stuff about the connection between ide and ida deleated mhz clock bit width mb sec if ide speed come from ida where does the mb s sighted for ide come from scsi is not complex it is just the way the industry uses and talks about it there are three key differences in scsi the controller chip the port and the software that is it let us look as scsi in from this stand point scsi asynchronous and synchronous modes software scsi driver only asynchronous is slower then synchronous mode only mb s vs mb s synchronous speeds can be reached by most scsi divices with a rewrite of the software driver as is the case for the mac quadra scsi bit this is the main source for the confusion this differs from scsi only in the controler chip in most machines in the mac and some pcs this is called fast scsi because it uses scsi ports and software drivers and can produce scsi speeds through scsi inspite of this even in the slower asynchronous mode average speed in asynchronous scsi mode mb s with mb s see in both quadras and higher end pcs synchronous mode just allows a higher burst rate mb s scsi bit two versions wide fast wide scsi requires two things over bit scsi a scsi software driver and a wide scsi port on the machine and the external device fast scsi also requires two things over bit scsi scsi driver software and that the recieving devise support bit fast scsi speed of both is the same mb s with mb s burst scsi bit also know as wide and fast scsi over bit scsi this requires scsi driver software wide scsi port and that the recieving devices also have a bit mode scsi chip as expected this is very expencive speed mb s with mb s bursts as i said simple seven versions of scsi seperated by software the controler chip and the port standarize the software and it drops to only five versions of scsi seperate by only hardware the chip and the port
