SUMMARY: SCSI Interface Question

From: Steve Boronski (spb@stoke.gov.uk)
Date: Wed Nov 18 1998 - 03:42:12 CST


Many Thanks to all who responded, it is not as simple as it seems and I
am still not 100% happpy, however I am sure now that it is single-ended.

However the documentation states: (Sunsolve 14075 infodoc SCSI PSD)

_______________________________________________________________________________

  Any combination of narrow/wide with single-ended/differential
  with non-fast/fast is possible.

  Fast/wide combo yields up to 20MB/sec throughput.

_______________________________________________________________________________

So I am still working on this, my StorageTEK DLT tapes are DIFFERENTIAL,
and my Sun Interface single-ended, which I would assume to be
in-compatible, but the above statement seems to disprove that. I am now
going to take a known tape drive which already conects to a Sun Ultra
system board scsi and try that as I suspect it may well be my cable.

Many thankes to thefollowing for their help:

> Hi:
> I think it is single-ended .
> You can easily find the answer from the back of the machine.
> single-end SCSI interface will show a
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Yu Haicheng

> Ah yes, the wonders of sun's web site ;))
>
> Try this URL
> http://www.sun.com/servers/enterprise/450/wp-arch/450-arch.pdf (for the
> E450, I'm sure the 250 has something similar). If you look at page 17
> it says that the SCSI is single-ended.
>
> regards
>
> Shriman Gurung

> It's single ended. It would tell you in the docs if it was
> Differential. Another way to check is to look at the maximum cable
> length specs. If they are around 2 meters, it's not differential.
>
> John
> John Stoffel

> I am almost sure it is Single Ended. There is a strong hint in the owner guide
> in the section below. see http://docs.sun.com:80
>
> About the SCSI Removable Media Bays and the External SCSI Port
>
> The removable media assembly located at the top front of the system provides
> mounting bays for two 5.25-inch, half-height (1.6-inch)
> SCSI devices. The upper SCSI bay (directly below the diskette drive bay) houses
> a CD-ROM drive. The lower bay accommodates a
> second SCSI device, such as an 8-mm tape, a 4-mm DDS-2 or DDS-3 tape, or a
> quarter-inch cassette tape drive. Both SCSI
> removable media bays are connected to the same SCSI bus as the internal disk
> drives. While this bus supports wide SCSI operation for
> the internal disk drives, the removable media portion of the bus operates in
> narrow SCSI mode only. The removable media assembly can
> accommodate wide SCSI (68-pin) devices, however these devices require a
> 50-to-68-pin adapter cable, and operate in narrow SCSI
> mode only.
>
> External SCSI devices are supported via a 68-pin SCSI connector located on the
> system's rear panel. This bus is UltraSCSI-capable
> (40 Mbytes per second) and can support additional external, single-ended, wide
> or narrow SCSI devices. The external SCSI bus is
> separate from the internal SCSI bus for removable media devices and internal
> disk drives. See Reference for the SCSI Connector for a
> diagram and pinout of the external SCSI connector.
>
> The external SCSI bus will support up to four external SCSI tape devices if the
> bus is used exclusively for tape devices. When other
> types of SCSI devices are present on the bus, a maximum of two SCSI tape devices
> are supported on the external SCSI bus. Additional
> external tape devices can be supported by installing appropriate PCI host
> adapter cards.
>
>
> I hope this helps
>
> Anthony Worrall

> Steve,
> The interface(s) are Fast Wide UltraSCSI Single Ended. Also
> note that the E450 has 2 onboard SCSI controllers ( Internal and
> External )
> where the E250 has just the one for both.
> >
> Best Regards,
>
> Steve Butterfield

>
> Ray Trzaska <rtrzaska@uk.mdis.com>

> it's ultra/wide/single-ended



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