[Sunhelp] Help reqd for SCSI errors !!

[Dale Ghent]

On Sat, 28 Oct 2000, Kalyandurga, Mohammed I wrote:

| 
| Is diffrential SCSI also Backward compatable ? Can Diff Scsi support USCSI
| Hard disks and other Peripherals ?.

No.

Diff SCSI can be the same as regular (single-ended) SCSI in terms of speed
(You can have Differential Fast-Wide SCSI-2, Differential UltraSCSI,
etc). The difference between the two is purely electrical.

What differential SCSI gives you is the ability to have longer cables
between your devices. Diff SCSI makes use of pins on the connector that
are unused with SE SCSI to ground each individual data pin (8 data pins
for narrow SCSI, 16 for Wide SCSI). This recudes the amount of electrical
inteference on the data pins and thus allows increased distances between
devices.

Why you cant use differenct devices on a SE bus, or a combination of the
two is that you'r connecting live pins to what should be dead pin on a SE
device, openning up the posibility of frying your SE devices, and surely
the differential devices wont like that, either.

/dale