[RndTbl] SCSI cable length
Hartmut W Sager
hwsager at marityme.net
Fri Jul 3 21:28:26 CDT 2015
Oops, I may have gotten something wrong. Web information suggests that the
AHA-2920 series cards are also bus-mastering, in which case, I can't
remember what's different between AHA-2920 and AHA-2940. But I do remember
that I used a lot of AHA-2940 series cards.
Hartmut W Sager - Tel +1-204-339-8331, +1-204-515-1701, +1-204-515-1700
On 3 July 2015 at 21:16, Hartmut W Sager <hwsager at marityme.net> wrote:
> Two of the most famous single-ended classic SCSI-2 host adapters of that
> era, using this 50-pin dense connector, were the Adaptec AHA-2920
> non-bus-mastering series and the Adaptec AHA-2940 bus-mastering series, for
> PCI slot motherboards. They also sported an internal 50-pin 2-row ribbon
> connector for internal SCSI drives (and a 34-pin 2-row ribbon connector for
> floppy drives in the case of the AHA-2922 and AHA-2942, I think).
> You could actually have both internal and external devices on the single
> SCSI chain (card in the middle), as long as you disabled the terminating
> resistor pack on the card itself. You then had to be especially careful in
> deciding which card/device would supply the terminating resistor power. I
> recall that Fujitsu hard drives were exceptionally problematic in these
> I presume you (Trevor) know all about having to set each SCSI
> drive/device, including the host adapter, to a unique SCSI ID, yes?
> Life with SATA and USB really is more pleasant.
> Hartmut W Sager - Tel +1-204-339-8331, +1-204-515-1701, +1-204-515-1700
> On 3 July 2015 at 19:48, Hartmut W Sager <hwsager at marityme.net> wrote:
>> > I'm a big SCSI guy, but ...
>> I too am an old SCSI fan, but my interest started to wane when so many
>> SCSI signalling standards and connectors began to proliferate together with
>> SCSI moving totally into the high-end server realm and away from "ordinary"
>> peripherals. Oh, and then there was that "termination power" headache
>> (usually selected/deselected by jumpers).
>> > The device has a standard dense 50-pin 2-row connector. I thought at
>> first that meant for sure LVD, but now I'm thinking it just means ultra.
>> It doesn't even mean "ultra", let alone HVD/LVD. That connector became
>> the norm during the single-ended classic SCSI 2 generation - to my great
>> chagrin, since the Centronics 50-pin connector was so much better.
>> > Is there a way to know what signalling this device uses based just on
>> the connector?
>> No, but:
>> > I checked all available interent specs, incl the original manual, for
>> the device and *nothing* specifies anything other than "SCSI".
>> Since the original manual (lucky you to have that!) doesn't specify
>> anything other than "SCSI", it is a near certainty that this isn't LVD or
>> HVD, but simply good old single-ended classic SCSI (of at least SCSI 2
>> generation). It probably isn't "ultra" either, especially if it's a
>> scanner or CD drive or similar slow device rather than a hard drive.
>> Hartmut W Sager - Tel +1-204-339-8331, +1-204-515-1701, +1-204-515-1700
>> On 3 July 2015 at 16:06, Trevor Cordes <trevor at tecnopolis.ca> wrote:
>>> I have an external SCSI device that I'd like to plug in on a 10-15'
>>> The device has a standard dense 50-pin 2-row connector. I thought at
>>> first that meant for sure LVD, but now I'm thinking it just means ultra.
>>> I need LVD to get over 1.5M cable length, according to spec. LVD lets me
>>> go to 12M it appears. If it's just ultra then I'm SOL, I guess.
>>> Is there a way to know what signalling this device uses based just on the
>>> connector? I checked all available interent specs, incl the original
>>> manual, for the device and *nothing* specifies anything other than
>>> I'm a big SCSI guy, but my memory on the subject is starting to get
>>> hazy due to disuse...
>>> Roundtable mailing list
>>> Roundtable at muug.mb.ca
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