re ide vs scsi wlsmith valve heart rri uwo ca wayne smith writes wayne amtower spacecoast org writes ide also uses dma techniques i believe floppy controller also uses dma and most a d boards also use dma dma is no big deal and has nothing to do directly with scsi no the simple style ide controller does not use dma the cpu performs the data transfer with a string move instruction this requires that the cpu stop what it had been doing and transfer the data only the smart drive controllers be they ide or scsi can transfer via dma these controllers tend to cost the same wether they are ide or scsi to get the dma benefits ide must sacrifice it s price advantage on the controller for example when rewinding or formatting a tape the command is issued to the controller and the bus is released to allow access to other devices on the bus this greatly increases productivity or at least do something else while backing up your hard drive which happens to be what i am doing while reading this group you can thank your software for that if dos had a few more brains it could format floppies etc while you were doing something else the hardware will support it but dos at least won t again this has nothing to do with scsi floppies aren t on the ide bus your arguement makes no sense this isn t an ide issue the floppys have their own processor on their controller board which handles all of these commands the difference between ide and scsi is that all scsi peripherials are intelligent they each have their own controller they depend on the cpu to do fewer things for them i e ide drives needing a processor to transfer their data its a long story but i still use ide on my except for the cdrom which thanks to scsi i can move between both machines if and when scsi is better standardized and supported on the ibm clone machines i plan to completely get rid of ide and if you stick with dos you ll wonder why you can t multitask again i ask why can t a unix or os type os do all the miraculous things with an ide harddrive that it can with a single scsi hard drive the dettach callback mechanism alows the cpu to make requests of the devices on the scsi bus and then dettach and go about its business later when the device is done it issues a callback to say that the data has arrived or the function has completed most scsi cards will also dma the data into memory without the interupting the cpu therefore allowing it to continue working uninterupted ide supports no such concept as dettach callback can you see how this would be a win in any multitasking system david willmore willmore iastate edu death before dishonor better dead than greek david willmore ever noticed how much they look like orchids lovely
