"Arno Wagner" wrote in message
In comp.sys.ibm.pc.hardware.storage Jeff Richards wrote:
Your comments are confused. There's no such thing, in SCSI or IDE, as a
terminated or unterminated device. There's a device, a terminator, or no
device. The terminator is a cheap way of pretending some sort of device is
connected, and it's important for SCSI mainly because of the cable lengths
involved. It doesn't really matter for IDE because the impact of an
unterminated connector on the signal quality (ringing, overshoot) is much
less with the shorter lengths involved, and the IDE interface can cope with
it. But there is still a difference in signal quality between an IDE cable
with a device connected and one without.

An 'Inactive' IDE device is not particularly high resistance, and certainly
has an impact on signal quality compared with an open connector.

SCSI is complicated today.

No it isn't, just complicated for you.

U2W cables are actively terminated.

No, they aren't. Ultra SCSI and LVD buses are actively terminated.

Older standards allow terminated devices (i.e. devices with internal
termion) as well as external terminators.

You got that backwards too.


As it turns out UDMA capable devices has some sort of half-assed
device terminaton,

No, they have series termination.

i.e. _every_ device on the bus has some pull-up or pull-down resistirs.

Quite inelegant IMO.

Quite elegant actually and no one cares OYO. Least T13.


Arno