Quoting Karl E. Jrgensen ([EMAIL PROTECTED]): > > If I can get to understand Scsi and find it a viable alternative to > > IDE, it was my intention to attach a CD writer and some new > > harddrives externally (the board provides for this). Here again > > I'm lost - some people I've spoken to insist only one device can > > be attached externally whilst the literature clearly says up to 7. > SCSI takes at least 7. Later versions of SCSI (where the last address bit is > used) can take up to 15. > > > Furthermore, here in the UK no-one appears to stock any 'boxes' > > or whatever for more than one device. A stock explanation seems > Why should they? If they can sell one controller per device? :-) They > probably would argue that it's "just overengineering to be safe" :-) > On a serious note though, some cheaper cards do take quite a bit of CPU > overhead, and I ended up with such a card when I bought by SCSI CD-Rewriter. > Although it *can* take 7 devices (I now have a 18Gb disk, a CD-RW and a tape > station running off it), it doesn't seem to have an impressive bandwith... > Something to do with PCI-busmastering I've been told... > > > to be "haven't seen any for years - there's no call for them" > > (One 'charming' individual said he knows nothing technical > > about computer parts "I only sell them".
I'm not sure what John means by "boxes" for more than one device. A SCSI card will typically have one external connector and possibly more than one internal connector to cater for different connector-types. The documentation will warn you not to use more than any two connectors at the same time (else you have a star configuration, not a chain). To connect more than one scsi device to the external connector, they have to be daisy-chained, and most devices will carry two connectors to allow this. The order of daisy-chaining can be important when you have lame 8-bit devices that don't carry through the wires for bits 9--16, or which have tacky 25-way D connectors which are not real SCSI connectors anyway. Cheers, -- Email: [EMAIL PROTECTED] Tel: +44 1908 653 739 Fax: +44 1908 655 151 Snail: David Wright, Earth Science Dept., Milton Keynes, England, MK7 6AA Disclaimer: These addresses are only for reaching me, and do not signify official stationery. Views expressed here are either my own or plagiarised.