devil%TECHUNIX.BITNET@cunyvm.cuny.edu (Gil Tene) (08/12/90)
Hello Netland, this is a SCSI termination question : I know of two very different ways of terminating SCSI cables; one is with terminator plugs, and the other is with device on-board terminators. This disk I have here, for a Sun, says that some Sun SCSI busses do not provide termination power on the SCSI bus, and termination must therefore be done by on-board terminators, with the disk supplying termination power. I much prefer using SCSI termination plugs to openning the box up every time I want to reconfig something... Now for the question(s) : - Which Suns don't provide termination power on the SCSI bus ? (Does the Sparcstation 1,1+,SLC,IPC ?) - If the Sun DOES provide termination power, can setting the terminators on the drive to use the drive's power HURT anything (two power sources) ? AdvThanks, Gil. -- -------------------------------------------------------------------- | Gil Tene "Some days it just doesn't pay | | devil@techunix.technion.ac.il to go to sleep in the morning." | --------------------------------------------------------------------
chris@com50.c2s.mn.org (Chris Johnson) (08/27/90)
In article <1990Aug13.011541.6424@rice.edu> devil%TECHUNIX.BITNET@cunyvm.cuny.edu (Gil Tene) writes: > >Hello Netland, this is a SCSI termination question : > >I know of two very different ways of terminating SCSI cables; one is with >terminator plugs, and the other is with device on-board terminators. > >- Which Suns don't provide termination power on the SCSI bus ? > (Does the Sparcstation 1,1+,SLC,IPC ?) > >- If the Sun DOES provide termination power, can setting the terminators > on the drive to use the drive's power HURT anything (two power sources) ? The Sparcstation 1 and 1+ provide termination power throught a socketed fuse. By extension, I would guess the SLC and IPC do also, but I haven't seen the guts of one yet to know for sure. [Ed's Note: Just for grins, I've been dealing with this problem a little myself lately, and was informed that the Sun-3 (at least the smaller ones 50,60,80) do not provide term power on the SCSI bus. -bdg] I would imagine the most drives which allow you to jumper termination power for drive-mounted terminators (like all Wrens) only drive term-power into those resistors, and not onto the SCSI bus. If multiple devices drive term-power on the SCSI bus, they should have back current protection diodes. I don't know if the Sun CPU boards have this, or not, but some SCSI devices do. ...Chris Johnson chris@c2s.mn.org ..uunet!bungia!com50!chris Com Squared Systems, Inc. St. Paul, MN USA +1 612 452 9522