cook@stout.atd.ucar.edu (Forrest Cook) (08/22/90)
I am looking for A SCSI terminator in the DD-50P format.
Has anybody found a company that sells these things?
Black Box only sells Macintosh SCSI terminators with the DB-25 connector.
While on the topic of SCSI, is the SCSI standard only for signal lines,
not connectors? So far, we have the following SCSI connectors:
DD-50 Sun 4/280 and some peripherals
mini DD-50 Sun Sparcstations
dual-inline Most circuit board SCSI connections
AMP "centronix" who knows?
AMP MT shielded dual-inline Ardent, Emulex
DB-50 Macintosh
I also just received an STC 9 track tape drive that has an option for
"differential" SCSI, that shoots down the idea of an electrical standard.
--
^ ^ Forrest Cook - Beware of programmers who carry screwdrivers - LB
/|\ /|\ cook@stout.atd.ucar.edu WB0RIO (This posting is an OPINION)
/|\ /|\ {husc6|rutgers|ames|gatech}!ncar!stout!cookdavid@cs.uow.edu.au (David E A Wilson) (08/22/90)
cook@stout.atd.ucar.edu (Forrest Cook) writes: >While on the topic of SCSI, is the SCSI standard only for signal lines, >not connectors? So far, we have the following SCSI connectors: >DD-50 Sun 4/280 and some peripherals >mini DD-50 Sun Sparcstations >dual-inline Most circuit board SCSI connections >AMP "centronix" who knows? >AMP MT shielded dual-inline Ardent, Emulex >DB-50 Macintosh 25 The standard specifies the dual-inline form for the circuit board. The appendix to the standard (NOT part of the standard) has the 50 way AMP connector (like the Centronics 36 way connector only wider) as alternative 2. I cannot remember what alternative 1 was. The Sun DD-50, Sun sub micro SCSI & Apple DB-25 connectors are not mentioned but then the standard does not mandate specific external connectors. >I also just received an STC 9 track tape drive that has an option for >"differential" SCSI, that shoots down the idea of an electrical standard. That is part of the standard as well. By using differential signals you can have longer cable runs etc. Pity the connectors are the same. David Wilson Dept Comp Sci, Uni of Wollongong david@cs.uow.edu.au
lc@goanna.cs.rmit.oz.au (leon) (08/22/90)
In article <1990Aug22.045225.23292@cs.uow.edu.au>, cook@stout.atd.ucar.edu (Forrest Cook) & david@cs.uow.edu.au (David E A Wilson) write: > >While on the topic of SCSI, > > >I also just received an STC 9 track tape drive that has an option for > >"differential" SCSI, that shoots down the idea of an electrical standard. > That is part of the standard as well. By using differential signals you can > have longer cable runs etc. Pity the connectors are the same. > Does anyone have a pinout they can post for the 'differential'-type connection ? This will undoubtably come in handy one day.
wilker@descartes.math.purdue.edu (Clarence Wilkerson) (08/22/90)
Note that the External connectors used on Sun 3/50-60's do not match up pin number by pin number with the dual inline numbers. Rather, it's arranged so that when a flat 50 pin cable is clamped on, and connected to a similar arrangement, things are untwisted. To clarify what I mean, pin 3 on the scsi bus is not pin 3 on the external connector, in the usual numbering scheme printed on the DB50 connectors. .
henry@zoo.toronto.edu (Henry Spencer) (08/23/90)
In article <8287@ncar.ucar.edu> cook@stout.atd.ucar.edu (Forrest Cook) writes: >While on the topic of SCSI, is the SCSI standard only for signal lines, >not connectors? ... The SCSI standard made some attempt to specify connectors, albeit a half- hearted one with a couple of options. Unfortunately, the pinheads working for certain manufacturers think it is their god-given right to use a new and different connector any time the old one proves slightly inconvenient. There is, unfortunately, a considerable tradition of this sort of nonsense in the PC business, and it's not likely to stop. -- Committees do harm merely by existing. | Henry Spencer at U of Toronto Zoology -Freeman Dyson | henry@zoo.toronto.edu utzoo!henry
John_A_Pham@cup.portal.com (08/23/90)
Here's the pin description for SCSI differential
Signal Pin Number Signal
*shield ground 1 2 ground
+db0 3 4 -db0
+db1 5 6 -db1
+db2 7 8 -db2
+db3 9 10 -db3
+db4 11 12 -db4
+db5 13 14 -db5
+db6 15 16 -db6
+db7 17 18 -db7
+dbp (parity) 19 20 -dbp
ground 21 22 ground
ground 23 24 ground
**tempwr 25 26 **tempwr
ground 27 28 ground
+atn 29 30 -atn
ground 31 32 ground
+bsy 33 34 -bsy
+ack 35 36 -ack
+rst 37 38 -rst
+msg 39 40 +msg
+sel 41 42 -sel
+c/d 43 44 -c/d
+req 45 46 -req
+io 47 48 -io
ground 49 50 ground
*Optional shield ground on some cables
**these pins are reserved for providing optional terminator power (+5V)