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- Path: quasar.xs4all.nl!ekrieger
- Subject: Re: Termination Quantum Fireball 1080S
- Newsgroups: comp.periphs.scsi,comp.sys.amiga.hardware
- Followup-To: comp.periphs.scsi,comp.sys.amiga.hardware
- References: <236.6596T678T2599@ibm.net> <DLnut8.2Mn@ecf.toronto.edu>
- X-Newsreader: TIN [AMIGA 1.3 950726BETA PL0]
- From: ekrieger@quasar.xs4all.nl (Eric Krieger)
- Message-ID: <ekrieger.1wl0@quasar.xs4all.nl>
- Date: Sun, 4 Feb 96 15:38:28 +0100
- Organization: Private, Delft [NL]
-
- KWONG CHUN-KUEN (kwong@ecf.toronto.edu) wrote (on Wed, 24 Jan 1996 01:00:44 GMT):
-
- > Someone recommended that I get "active termination"...
- > I have no idea what that is. Its not described in the FAQ..
-
- May I suggest to look again:
-
- [... Taken from: "comp.periphs.scsi FAQ part 2 of 2" ...]
-
- ====
- QUESTION: What is Active Termination?
- ANSWER From: eric@telebit.com (Eric Smith)
- and brent@auspex.com (Brent R. Largent)
- ====
-
-
- An active terminator actually has one or more voltage regulators to produce
- the termination voltage, rather than using resistor voltage dividers.
-
- This is a passive terminator:
-
-
- TERMPWR ------/\/\/\/------+------/\/\/\/----- GND
- |
- |
- SCSI signal
-
- Notice that the termination voltage is varies with the voltage on the
- TERMPWR line. One voltage divider (two resistors) is used for each SCSI
- signal.
-
-
- An active terminator looks more like this (supply filter caps omitted):
-
- 2.85 Volt Regulator
- +-----------+ +2.85V 110 Ohms
- TERMPWR -----| in out |------+------/\/\/\/-------SCSI signal
- | gnd | |
- +-----------+ |
- | +------/\/\/\/-------SCSI signal
- | |
- GND ---------------+ |
- +------/\/\/\/-------SCSI signal
- |
- etc.
-
- Assuming that the TERMPWR voltage doesn't drop below the desired termination
- voltage (plus the regulator's minimum drop), the SCSI signals will always
- be terminated to the correct voltage level.
-
- Several vendors have started making SCSI active terminator chips,
- which contain the regulator and the resistors including Dallas
- Semiconductor, Unitrode Integrated Circuits and Motorola
-
- ....
- [... End of "comp.periphs.scsi FAQ part 2 of 2" ...]
-
- With kind regards,
- --
- | Eric Krieger : ekrieger@quasar.xs4all.nl | Fido-Net: 2:285/1.10 |
- | Q U A S A R : Last Point of Endless Time | AmigaNet: 39:102/1.21 |
-