re ide vs scsi in article c lkev hpj feanor xel com shaw feanor xel com greg shaw writes why don t you start with the spec sheet of the isa bus first you can quote scsi specs till you re blue in the face but if they exceed the isa bus capability then what s the point who said isa was necessary eisa or vlb are the only interfaces worth investing thousands of dollars e g a new pc s worth of money in then don t complain maybe it wasn t you that scsi was so expensive on pc s because all we ve had until a year or two ago was the isa bus ie no one buys scsi for isa because isa is slow are you saying that scsi on an isa bus is not an automatic winner when compared to ide you didn t read to carefully vlb ide uses the same connection mechanism as standard ide if transfer rate is limited by ide whether it s interfaced to isa eisa or vlb matters not i get different transfer rates out of my ide when i change my isa bus speed on mine for one thing scsi blows ide out of the water hands down if ide has better throughput why isn t it used on workstations and file servers ide is just a variant of the old ibm mfm at controller at least that s how it looks from a software point of view it was never meant to be an all encompassing protocal standard to be implimented across different platforms is there any argument that ide can or can t transfer data from the ide drive at least as fast as the drive is able to provide the data are scsi versions of ide drives able to deliver higher sustained transfer rates to their scsi interface because of a higher rpm platter different arrangement of heads etc given the original question scsi used only as a single hard drive controller is it then necessary to get a scsi drive that will do at least maybe megs sec for the scsi choice to make any sence what does a meg megs sec scsi drive cost no that s the nice thing on a multitasking os scsi can use both drives at once i ve got unix loaded on one of my pcs along with windogs and the os can only use one of the two ide drives at one time it s pretty ugly if data is going from one drive to another and if scsi has the ability to perform that transfer without the data having to go through the cpu or main memory then yes that is the optimal way to do it as far as i know ide can t do that but when the cpu wants data from both drives data to be stored in main memory are you saying that scsi can grab data from both drives at the same time and store transfer that data to main memory also at the same time working off irq and dma channel on an isa or whatever bus i just bought at quantum for my mac at home i paid for it i haven t seen ide drives cheaper a friend of mine just got a maxtor meg ide drive for that s million bytes or mega bytes with the basic interface he gets close to meg sec transfer on his does your figure include a few hundred for scsi drivers no actually we re talking about scsi being expensive simply because nobody did a common interface for the pc if they had a common read easily implemented method of adding scsi to a pc like as in a sun or mac then you d find scsi the connection medium of choice so you re saying that scsi would have been the default interface type considering that the vast majority of pc s don t have cd rom drives or tape backups or etc that most pc s only have or had hard drive and run dos that scsi hard drives cost a lot more than mfm or rll drives at the time and how common were scsi drives under megs to years ago there s a lot more than the lack of a common interface card that prevented scsi from becoming the connection medium of choice i won t argue that the scsi standard makes for a good well implimented data highway but i still want to know why it intrinsically better than ide on an isa bus when it comes to multi tasking os s when managing data from a single scsi hard drive on a single drive scsi is more expensive but on that point is it faster this is what all this is about do you get more performance for the money for all the people that will only have a single hard drive in their system regardless of the os will the scsi choice really give them more performance than ide but you bought your pc for expandibility so you d want to add more drives or whatever true but expandibility can also start on the bus which means the option is there for cd rom drives or tape backups that run off their own cards you can add many different types of devices and access them concurrently no argument this is always held up to the first time scsi buyer as the best reason but how many scsi devices will the first time scsi buyer eventually acquire again does it make sense to go scsi for a single hard drive system a scsi device works on many different machines i have a mac and a pc at home and moving hard drives between them is very nice with scsi hook them up and away they go with all the postings on the scsi i or ii specs are you really sure that pc and apple scsi hard drives are compatible and even if they are is the data accessible from either machine ie are there no formatting partitioning or file table differences is it really plug n play scsi devices work together better than ide devices for instance recently i added an older connor meg ide to a maxtor meg ide the connor must be setup as the slave it will work no other way on scsi you set the address check the termination plug it in and away it goes so the c drive on the connor becomes a logical d drive to dos is this really a problem i have a problem with ide s mutual exclusion i notice that the time it takes to switch from accessing drive c to drive d is quite long as compared to the time it takes to switch from drive c to d on a scsi system under a multitasking os this is very noticable as many things can be going on at once after having two ide drives in my system for temporary file transfers i have never seen any differences when switching between drives nor have i ever seen any differences when transfering files between drives or to from the same drive one neat thing that i ve noticed lately a fringe benefit has been the ability to add older almost dead drives as storage on a scsi system with little problem we ve got a bunch of almost dead meg drives that i ve added to my pc i ve now got the interface full but it does allow me to have meg drives meg drive tape drive and meg drive all on the same card that is nice as long as the power supply can keep up i do believe that there is the possibility for up to ide drives on a pc simply put scsi is handier than ide no mysterious jumpers to figure out but what about mysterious and expensive drivers to figure out at least ide doesn t require drivers that consume precious conventional dos memory
