re ide vs scsi wlsmith valve heart rri uwo ca wayne smith writes this doesn t answer the original question is os a multi user os and no mention was made of an ether card either but from a disk data point of view why does scsi have an advantage when it comes to multi tasking data is data and it could be anywhere on the drive can scsi find it faster can it get it off the drive and into the computer faster does it have a better cache system i thought scsi was good at managing a data bus when multiple devices are attached if we are only talking about a single drive explain why scsi is inherently faster at managing data from a hard drive you are making the same mistake i did you are confusing the drive interface to the data throughput interface again from my mac ibm info sheet available by ftp on sumex aim stanford edu in the info mac report as mac ibm compare txt expansion both mac ibm scsi only external device expansion interface common to both mac and ibm allows the use of any device hard drive printer scanner nubus card expansion mac plus only some monitors and cd rom apple developed some specifications for scsi controlers while ibm has no exact controller specifications which results in added incompatibilities on ibm machines main problem there are a lot of external devices which are internal terminated which causes problems for more then two devises off the scsi port a scsi chain is supposed to be terminated only at the begining and at the end any other set up causes problems for either mac or ibm scsi devices per scsi controller bit asynchronous mb s ave and synchronous mb s max transfer base bit scsi requires a scsi controler chip and can provide only fast scsi not wide scsi which are both bit interfaces see scsi scsi devices per scsi controller in scsi mode scsi is fully scsi complient and tends to be implimented as a very fast scsi since it needs a different controller interface in both hardware which tends to be very expendsive and software transfer speeds are mb s with mb s burst bit mb s with mb s burst bit and mb s with mb s burst bit wide and fast scsi in scsi mode is limited to devices and reduced bit or bit fast only throughput due to the difference between scsi and wide scsi ports ibm hd interfaces limited to hard drives by design or lack of development ide integrated device electronics currently the most common standard and is mainly used for medium sized drives can have more than one hard drive asynchronous transfer mb s max so at its lowest setting scsi interface in asynchronous scsi mode averages the through put maximum of ide in asynchronous mode in full scsi mode it blows poor ide out the window down the street and into the garbage can the problem becomes can the drive mechanisim keep up with those through put rates and that is where the bottleneck and cost of scsi comes from not the interface itself but more and more from drive mechanisims to use the scsi through put the cost of scsi interface is a self fulliling prophisy few people buy scsi because it is so expencive for the pc which in turn convices makes that mass producing scsi which would reduce its cost is unwarented and so scsi is expencive that is the effect of the rule of scale the more items sold the less each item has to bare the brunt the cost of manufacture and so the less each item has to cost scsi allows a drive mechanisims through put to be limited by the drive while ide itself limits the through put
