| Author |
Message |
George Hester
Guest
|
 Posted:
Wed Jun 29, 2005 7:27 am Post subject:
Re: NOT a lot different |
|
|
I have an onboard Adaptec AHA-2940/2940UW/2940D PCI SCSI Controller. This
is what Windows XP says in Device Manager. These connectors are the boards
I use to access the SCSI drives Metropolis 3391 9.1 GB. The connector on
the MOBO says SCSI UW.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9stlp$97s$1@news.freedom2surf.net...
25&mitem=34
| Quote: |
Those are old fashioned boards for Ultra Fast, Wide SCSI. They will not
work in LVD (Ultra2, Ultra3/Ultra160 or Ultra 320 mode).
What type of Host Adapter and SCSI periphirals do you have? |
|
|
| Back to top |
|
 |
George Hester
Guest
|
| Posted:
Wed Jun 29, 2005 7:27 am Post subject:
Re: NOT a lot different |
|
|
Well thank you that was my intent all along. The ones you see at my second
post are the ones I have. So I think you can understand why when I saw what
I saw at eBay I was wondering why they didn't look like mine.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9sua3$9dt$1@news.freedom2surf.net...
| Quote: | On 21/06/05 23:24, George Hester wrote:
Yes but will the ones I see at eBay work? That's my issue. They don't
have
LEDs what else don't they have? The ability to work?
Depends on what you mean by "Work".
Just having had a second glance I noticed that some of the things you
described as connectors are not, they are Jumpers.
The adapters your URL pointed at are infact not so standard, but very
expensive.
There are two differences with the cheaper ones you pointed at in your
first posting:
1 These have built-in SCSI terminators, rather unusual and the large
number of jumpers looks to be there to enable/disable the terminators.
2 These are not LVD compatible, i.e only useful with old kit.
Did I say they are expensive? Shamefully so!
It seems your understanding of SCSI could do with reading some basic
information on how it works.
--
George Hester
_______________________________
"Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message
news:yXmte.338823$cg1.129226@bgtnsc04-news.ops.worldnet.att.net...
"George Hester" <hesterloli@hotmail.com> wrote in message
news:Msgte.26217$fp6.5436@twister.nyroc.rr.com...
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
That's the standard product. One with all those extra
headers/connectors
is
not anything usual.
|
|
|
| Back to top |
|
|
Arie Bant
Guest
|
| Posted:
Thu Jun 30, 2005 5:31 am Post subject:
Re: NOT a lot different |
|
|
On 29/06/05 04:39, George Hester wrote:
| Quote: | I have an onboard Adaptec AHA-2940/2940UW/2940D PCI SCSI Controller. This
is what Windows XP says in Device Manager. These connectors are the boards
I use to access the SCSI drives Metropolis 3391 9.1 GB. The connector on
the MOBO says SCSI UW.
|
The MS Windows XP type indication is too generic. It groups a number of
adapters together that are rather different in the way they interface
with periphirals. The AH2940 has a single-ended "narrow" or 8-bit
interface, the AHA2940D has a (High Voltage) differential interface.
Judging by the print on the MoBo I would assume your HBA is an
AHA2940UW, which has an "Ultra Fast" and "Wide" or 16-bit interface.
That means it can run the bus at Ultra Fast clock speed, i.e.20 Mhz (=40
MBytes/second on the wide bus).
At that speed you should be using active termination for reliable data
transfers.
The termination on the SCA adapter(s) you already have is passive,
judging from the picture at the URL you provided.
That means you should not be using the termination on that adapter, but
use a normal end-of-cable terminator internally.
Recapitulating:
The $39 SCA adapter has (a) LED(s) you cannot see from the outside and
terminators you should not use and is not compliant with LVD.
The $9 SCA adapter has none of that but is LVD compliant up to ULTRA320.
So why would you want to spend 39 dollar and effectively get less than
you would for $ 9 ?
| Quote: |
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9stlp$97s$1@news.freedom2surf.net...
On 19/06/05 16:47, George Hester wrote:
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
Those are old fashioned boards for Ultra Fast, Wide SCSI. They will not
work in LVD (Ultra2, Ultra3/Ultra160 or Ultra 320 mode).
What type of Host Adapter and SCSI periphirals do you have?
|
|
|
| Back to top |
|
|
Arie Bant
Guest
|
| Posted:
Thu Jun 30, 2005 5:45 am Post subject:
Re: NOT a lot different |
|
|
On 29/06/05 04:34, George Hester wrote:
| Quote: | Well thank you that was my intent all along. The ones you see at my second
post are the ones I have. So I think you can understand why when I saw what
I saw at eBay I was wondering why they didn't look like mine.
|
They look like that because passive termination has become obsolete and
no manufacturer I know of puts passive termination on anything these
days, because "narrow" 50-pin cabling is not compliant with LVD and
because the internal LED is generally rather useless compared to having
a LED on the front panel of the machine and it saves money not to put it on.
Quite honestly I can only explain your "wondering" as a result of a lack
of understanding of SCSI. With respect, there is no rational
explanation why one should expect new SCA adapters to look like those
used before "ULTRA" SCSI was introduced.
| Quote: |
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9sua3$9dt$1@news.freedom2surf.net...
On 21/06/05 23:24, George Hester wrote:
Yes but will the ones I see at eBay work? That's my issue. They don't
have
LEDs what else don't they have? The ability to work?
Depends on what you mean by "Work".
Just having had a second glance I noticed that some of the things you
described as connectors are not, they are Jumpers.
The adapters your URL pointed at are infact not so standard, but very
expensive.
There are two differences with the cheaper ones you pointed at in your
first posting:
1 These have built-in SCSI terminators, rather unusual and the large
number of jumpers looks to be there to enable/disable the terminators.
2 These are not LVD compatible, i.e only useful with old kit.
Did I say they are expensive? Shamefully so!
It seems your understanding of SCSI could do with reading some basic
information on how it works.
--
George Hester
_______________________________
"Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message
news:yXmte.338823$cg1.129226@bgtnsc04-news.ops.worldnet.att.net...
"George Hester" <hesterloli@hotmail.com> wrote in message
news:Msgte.26217$fp6.5436@twister.nyroc.rr.com...
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
That's the standard product. One with all those extra
headers/connectors
is
not anything usual.
|
|
|
| Back to top |
|
|
George Hester
Guest
|
| Posted:
Fri Jul 01, 2005 3:40 am Post subject:
Re: NOT a lot different |
|
|
"Arie Bant" <abant@mail.com> wrote in message
news:d9vfbj$3bk$1@news.freedom2surf.net...
| Quote: | On 29/06/05 04:34, George Hester wrote:
Well thank you that was my intent all along. The ones you see at my
second
post are the ones I have. So I think you can understand why when I saw
what
I saw at eBay I was wondering why they didn't look like mine.
They look like that because passive termination has become obsolete and
no manufacturer I know of puts passive termination on anything these
days, because "narrow" 50-pin cabling is not compliant with LVD and
because the internal LED is generally rather useless compared to having
a LED on the front panel of the machine and it saves money not to put it
on.
Quite honestly I can only explain your "wondering" as a result of a lack
of understanding of SCSI. With respect, there is no rational
explanation why one should expect new SCA adapters to look like those
used before "ULTRA" SCSI was introduced.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9sua3$9dt$1@news.freedom2surf.net...
On 21/06/05 23:24, George Hester wrote:
Yes but will the ones I see at eBay work? That's my issue. They don't
have
LEDs what else don't they have? The ability to work?
Depends on what you mean by "Work".
Just having had a second glance I noticed that some of the things you
described as connectors are not, they are Jumpers.
The adapters your URL pointed at are infact not so standard, but very
expensive.
There are two differences with the cheaper ones you pointed at in your
first posting:
1 These have built-in SCSI terminators, rather unusual and the large
number of jumpers looks to be there to enable/disable the terminators.
2 These are not LVD compatible, i.e only useful with old kit.
Did I say they are expensive? Shamefully so!
It seems your understanding of SCSI could do with reading some basic
information on how it works.
--
George Hester
_______________________________
"Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message
news:yXmte.338823$cg1.129226@bgtnsc04-news.ops.worldnet.att.net...
"George Hester" <hesterloli@hotmail.com> wrote in message
news:Msgte.26217$fp6.5436@twister.nyroc.rr.com...
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
That's the standard product. One with all those extra
headers/connectors
is
not anything usual.
|
With all due respect, "there is no rational explanation why one should
expect new SCA adapters to look like those used before "ULTRA" SCSI was
introduced," because that is what I have and they work. That seems rational
to me not to you?
--
George Hester
_______________________________ |
|
| Back to top |
|
|
George Hester
Guest
|
| Posted:
Fri Jul 01, 2005 3:44 am Post subject:
Re: NOT a lot different |
|
|
No reason. So Arie you are saying the connectors I posted at eBay will
work? That is basically all I want. The LED is pretty but not necessary I
am just trying to make sure that what I buy will work. And since I could
not compare what I saw at eBay satisfactorily with what I have and what I
have works I asked my original question.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9vegc$357$1@news.freedom2surf.net...
| Quote: | On 29/06/05 04:39, George Hester wrote:
I have an onboard Adaptec AHA-2940/2940UW/2940D PCI SCSI Controller.
This
is what Windows XP says in Device Manager. These connectors are the
boards
I use to access the SCSI drives Metropolis 3391 9.1 GB. The connector
on
the MOBO says SCSI UW.
The MS Windows XP type indication is too generic. It groups a number of
adapters together that are rather different in the way they interface
with periphirals. The AH2940 has a single-ended "narrow" or 8-bit
interface, the AHA2940D has a (High Voltage) differential interface.
Judging by the print on the MoBo I would assume your HBA is an
AHA2940UW, which has an "Ultra Fast" and "Wide" or 16-bit interface.
That means it can run the bus at Ultra Fast clock speed, i.e.20 Mhz (=40
MBytes/second on the wide bus).
At that speed you should be using active termination for reliable data
transfers.
The termination on the SCA adapter(s) you already have is passive,
judging from the picture at the URL you provided.
That means you should not be using the termination on that adapter, but
use a normal end-of-cable terminator internally.
Recapitulating:
The $39 SCA adapter has (a) LED(s) you cannot see from the outside and
terminators you should not use and is not compliant with LVD.
The $9 SCA adapter has none of that but is LVD compliant up to ULTRA320.
So why would you want to spend 39 dollar and effectively get less than
you would for $ 9 ?
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9stlp$97s$1@news.freedom2surf.net...
On 19/06/05 16:47, George Hester wrote:
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
Those are old fashioned boards for Ultra Fast, Wide SCSI. They will not
work in LVD (Ultra2, Ultra3/Ultra160 or Ultra 320 mode).
What type of Host Adapter and SCSI periphirals do you have?
|
|
|
| Back to top |
|
|
Arie Bant
Guest
|
| Posted:
Fri Jul 01, 2005 7:27 am Post subject:
Re: NOT a lot different |
|
|
On 30/06/05 23:44, George Hester wrote:
| Quote: | No reason. So Arie you are saying the connectors I posted at eBay will
work? That is basically all I want. The LED is pretty but not necessary I
am just trying to make sure that what I buy will work. And since I could
not compare what I saw at eBay satisfactorily with what I have and what I
have works I asked my original question.
--
George Hester
|
Dear George,
Of course I cannot categorically claim that these $9 adapters will work.
But I see absolutely no reason why they would not work.
I am using some very much like these myself without any problem at all.
I estimate the chance they will work at 99.99 % or higher.
That is allowing for 1 in 10,000 to be a faulty one that slipped through
quality control. I am sure if you happen to get that one, they will
replace it for you.
Arie Bant.
| Quote: | _______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9vegc$357$1@news.freedom2surf.net...
On 29/06/05 04:39, George Hester wrote:
I have an onboard Adaptec AHA-2940/2940UW/2940D PCI SCSI Controller.
This
is what Windows XP says in Device Manager. These connectors are the
boards
I use to access the SCSI drives Metropolis 3391 9.1 GB. The connector
on
the MOBO says SCSI UW.
The MS Windows XP type indication is too generic. It groups a number of
adapters together that are rather different in the way they interface
with periphirals. The AH2940 has a single-ended "narrow" or 8-bit
interface, the AHA2940D has a (High Voltage) differential interface.
Judging by the print on the MoBo I would assume your HBA is an
AHA2940UW, which has an "Ultra Fast" and "Wide" or 16-bit interface.
That means it can run the bus at Ultra Fast clock speed, i.e.20 Mhz (=40
MBytes/second on the wide bus).
At that speed you should be using active termination for reliable data
transfers.
The termination on the SCA adapter(s) you already have is passive,
judging from the picture at the URL you provided.
That means you should not be using the termination on that adapter, but
use a normal end-of-cable terminator internally.
Recapitulating:
The $39 SCA adapter has (a) LED(s) you cannot see from the outside and
terminators you should not use and is not compliant with LVD.
The $9 SCA adapter has none of that but is LVD compliant up to ULTRA320.
So why would you want to spend 39 dollar and effectively get less than
you would for $ 9 ?
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9stlp$97s$1@news.freedom2surf.net...
On 19/06/05 16:47, George Hester wrote:
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
Those are old fashioned boards for Ultra Fast, Wide SCSI. They will not
work in LVD (Ultra2, Ultra3/Ultra160 or Ultra 320 mode).
What type of Host Adapter and SCSI periphirals do you have?
|
|
|
| Back to top |
|
|
Arie Bant
Guest
|
| Posted:
Fri Jul 01, 2005 7:27 am Post subject:
Re: NOT a lot different |
|
|
On 30/06/05 23:40, George Hester wrote:
| Quote: | "Arie Bant" <abant@mail.com> wrote in message
news:d9vfbj$3bk$1@news.freedom2surf.net...
On 29/06/05 04:34, George Hester wrote:
Well thank you that was my intent all along. The ones you see at my
second
post are the ones I have. So I think you can understand why when I saw
what
I saw at eBay I was wondering why they didn't look like mine.
They look like that because passive termination has become obsolete and
no manufacturer I know of puts passive termination on anything these
days, because "narrow" 50-pin cabling is not compliant with LVD and
because the internal LED is generally rather useless compared to having
a LED on the front panel of the machine and it saves money not to put it
on.
Quite honestly I can only explain your "wondering" as a result of a lack
of understanding of SCSI. With respect, there is no rational
explanation why one should expect new SCA adapters to look like those
used before "ULTRA" SCSI was introduced.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9sua3$9dt$1@news.freedom2surf.net...
On 21/06/05 23:24, George Hester wrote:
Yes but will the ones I see at eBay work? That's my issue. They don't
have
LEDs what else don't they have? The ability to work?
Depends on what you mean by "Work".
Just having had a second glance I noticed that some of the things you
described as connectors are not, they are Jumpers.
The adapters your URL pointed at are infact not so standard, but very
expensive.
There are two differences with the cheaper ones you pointed at in your
first posting:
1 These have built-in SCSI terminators, rather unusual and the large
number of jumpers looks to be there to enable/disable the terminators.
2 These are not LVD compatible, i.e only useful with old kit.
Did I say they are expensive? Shamefully so!
It seems your understanding of SCSI could do with reading some basic
information on how it works.
--
George Hester
_______________________________
"Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message
news:yXmte.338823$cg1.129226@bgtnsc04-news.ops.worldnet.att.net...
"George Hester" <hesterloli@hotmail.com> wrote in message
news:Msgte.26217$fp6.5436@twister.nyroc.rr.com...
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
That's the standard product. One with all those extra
headers/connectors
is
not anything usual.
With all due respect, "there is no rational explanation why one should
expect new SCA adapters to look like those used before "ULTRA" SCSI was
introduced," because that is what I have and they work. That seems rational
to me not to you?
--
George Hester
_______________________________
|
Dear George,
I'll try again to explain in more detail.
The SCA adapter you have "looks" like it does because it has passive
terminators (the three yellow resistor SIL-packs) on board and some
jumpers to enable or disable these terminators and because it has a
"narrow" or 8-bit 50-pin connector. All that was fine in the days of 5
and 10 MHz SCSI bus speed and SCA-1. Since ULTRA SCSI and above
(Ultra2, Ultra3/160, Ultra320) the SCSI bus can operate at speeds in
excess of 20 MHz (40, 80, 160 Mhz).
At these speeds and for some other technical reasons, passive
termination does not work reliably if at all and in the case of a LVD
bus it simply does not work.
So it has become obsolete and I know of no manufacturer that still
incorporates passive termination on SCSI interfaces.
You state that you have Ultra SCSI working with these adapters. That is
very well possible. What you do not explain is what termination you
use. You could use an separate end-of-cable terminator of the active
sort or you could even use the build-in termination of some other
non-SCA SCSI device, active or not.
Perhaps you do not use active termination at all but passive
termination. Perhaps even the terminators on the SCA adapter. All that
is possible and may work, albeit that in the case of passive termination
the bus probably runs at a lower speed, i.e. 10 Mhz (=20 MB/sec), not at
20 MHz (=40 MB/sec).
Unless you do some measuring you would not neccesarily know the true bus
speed.
But in the right circumstances, only one device on the bus, a short
internal cable, you could be lucky and get away with it.
A matter of chance.
That is not what SCSI cabling now is designed for. In particular the $9
SCA adapters are explicitly advertised to be ULTRA320 compliant. That
means that passive termination is definitely useless because ULTRA320
uses Low Voltage Differential signals on the bus and that just does not
work with passive termination.
For the same reason there is no 50-pin connector on that adapter,
ULTRA320 is almost exclusively used on hard disk drives with a "Wide"
(=16 bit) interface and that excludes the 50-pin connectors.
You may also note that this adapter is lower than your older ones. That
is because it is made to fit behind a low profile 3.5" device,
aproximately 25 mm high.
The older ones were made to fit behind a "half height" drive,
approximately 40 mm high, so they had some more space for extra components.
I hope it is now clear to you why you cannot expect this SCA adapter to
look like your other ones.
Regards,
Arie Bant. |
|
| Back to top |
|
|
Folkert Rienstra
Guest
|
| Posted:
Fri Jul 01, 2005 5:35 pm Post subject:
Re: NOT a lot different |
|
|
"Arie Bant" <abant@mail.com> wrote in message news:d9vegc$357$1@news.freedom2surf.net
| Quote: | On 29/06/05 04:39, George Hester wrote:
I have an onboard Adaptec AHA-2940/2940UW/2940D PCI SCSI Controller.
This is what Windows XP says in Device Manager. These connectors are the
boards I use to access the SCSI drives Metropolis 3391 9.1 GB. The connector
on the MOBO says SCSI UW.
The MS Windows XP type indication is too generic.
It groups a number of adapters together that are rather different
in the way they interface with periphirals.
|
Nope. It's the driver for the 7870, 7880 and 7895 series chips.
| Quote: | The AH2940 has a single-ended "narrow" or 8-bit interface,
the AHA2940D has a (High Voltage) differential interface.
|
Nope. That is the AHA2944. The 2940D is the 2940Dual.
| Quote: | Judging by the print on the MoBo I would assume your HBA is an
AHA2940UW, which has an "Ultra Fast" and "Wide" or 16-bit interface.
That means it can run the bus at Ultra Fast clock speed, i.e.20 Mhz (=40
MBytes/second on the wide bus).
At that speed you should be using active termination for reliable data
transfers.
The termination on the SCA adapter(s) you already have is passive,
judging from the picture at the URL you provided.
|
Which apparently he *doesn't* have.
| Quote: |
That means you should not be using the termination on that adapter, but
use a normal end-of-cable terminator internally.
Recapitulating:
The $39 SCA adapter has (a) LED(s) you cannot see from the outside and
terminators you should not use and is not compliant with LVD.
The $9 SCA adapter has none of that but is LVD compliant up to ULTRA320.
So why would you want to spend 39 dollar and effectively get less than
you would for $ 9 ?
--
George Hester
"Arie Bant" abant@mail.com> wrote in message news:d9stlp$97s$1@news.freedom2surf.net...
On 19/06/05 16:47, George Hester wrote:
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=25&mitem=34
Those are old fashioned boards for Ultra Fast, Wide SCSI. They will not
work in LVD (Ultra2, Ultra3/Ultra160 or Ultra 320 mode).
What type of Host Adapter and SCSI periphirals do you have? |
|
|
| Back to top |
|
|
George Hester
Guest
|
| Posted:
Sun Jul 03, 2005 6:52 am Post subject:
Re: NOT a lot different |
|
|
Whatever all that means I can see you put some thought into it. I will keep
that for reference thanks.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:da2ahd$vug$1@news.freedom2surf.net...
| Quote: | On 30/06/05 23:40, George Hester wrote:
"Arie Bant" <abant@mail.com> wrote in message
news:d9vfbj$3bk$1@news.freedom2surf.net...
On 29/06/05 04:34, George Hester wrote:
Well thank you that was my intent all along. The ones you see at my
second
post are the ones I have. So I think you can understand why when I saw
what
I saw at eBay I was wondering why they didn't look like mine.
They look like that because passive termination has become obsolete and
no manufacturer I know of puts passive termination on anything these
days, because "narrow" 50-pin cabling is not compliant with LVD and
because the internal LED is generally rather useless compared to having
a LED on the front panel of the machine and it saves money not to put it
on.
Quite honestly I can only explain your "wondering" as a result of a lack
of understanding of SCSI. With respect, there is no rational
explanation why one should expect new SCA adapters to look like those
used before "ULTRA" SCSI was introduced.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9sua3$9dt$1@news.freedom2surf.net...
On 21/06/05 23:24, George Hester wrote:
Yes but will the ones I see at eBay work? That's my issue. They
don't
have
LEDs what else don't they have? The ability to work?
Depends on what you mean by "Work".
Just having had a second glance I noticed that some of the things you
described as connectors are not, they are Jumpers.
The adapters your URL pointed at are infact not so standard, but very
expensive.
There are two differences with the cheaper ones you pointed at in your
first posting:
1 These have built-in SCSI terminators, rather unusual and the large
number of jumpers looks to be there to enable/disable the terminators.
2 These are not LVD compatible, i.e only useful with old kit.
Did I say they are expensive? Shamefully so!
It seems your understanding of SCSI could do with reading some basic
information on how it works.
--
George Hester
_______________________________
"Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message
news:yXmte.338823$cg1.129226@bgtnsc04-news.ops.worldnet.att.net...
"George Hester" <hesterloli@hotmail.com> wrote in message
news:Msgte.26217$fp6.5436@twister.nyroc.rr.com...
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
That's the standard product. One with all those extra
headers/connectors
is
not anything usual.
With all due respect, "there is no rational explanation why one should
expect new SCA adapters to look like those used before "ULTRA" SCSI was
introduced," because that is what I have and they work. That seems
rational
to me not to you?
--
George Hester
_______________________________
Dear George,
I'll try again to explain in more detail.
The SCA adapter you have "looks" like it does because it has passive
terminators (the three yellow resistor SIL-packs) on board and some
jumpers to enable or disable these terminators and because it has a
"narrow" or 8-bit 50-pin connector. All that was fine in the days of 5
and 10 MHz SCSI bus speed and SCA-1. Since ULTRA SCSI and above
(Ultra2, Ultra3/160, Ultra320) the SCSI bus can operate at speeds in
excess of 20 MHz (40, 80, 160 Mhz).
At these speeds and for some other technical reasons, passive
termination does not work reliably if at all and in the case of a LVD
bus it simply does not work.
So it has become obsolete and I know of no manufacturer that still
incorporates passive termination on SCSI interfaces.
You state that you have Ultra SCSI working with these adapters. That is
very well possible. What you do not explain is what termination you
use. You could use an separate end-of-cable terminator of the active
sort or you could even use the build-in termination of some other
non-SCA SCSI device, active or not.
Perhaps you do not use active termination at all but passive
termination. Perhaps even the terminators on the SCA adapter. All that
is possible and may work, albeit that in the case of passive termination
the bus probably runs at a lower speed, i.e. 10 Mhz (=20 MB/sec), not at
20 MHz (=40 MB/sec).
Unless you do some measuring you would not neccesarily know the true bus
speed.
But in the right circumstances, only one device on the bus, a short
internal cable, you could be lucky and get away with it.
A matter of chance.
That is not what SCSI cabling now is designed for. In particular the $9
SCA adapters are explicitly advertised to be ULTRA320 compliant. That
means that passive termination is definitely useless because ULTRA320
uses Low Voltage Differential signals on the bus and that just does not
work with passive termination.
For the same reason there is no 50-pin connector on that adapter,
ULTRA320 is almost exclusively used on hard disk drives with a "Wide"
(=16 bit) interface and that excludes the 50-pin connectors.
You may also note that this adapter is lower than your older ones. That
is because it is made to fit behind a low profile 3.5" device,
aproximately 25 mm high.
The older ones were made to fit behind a "half height" drive,
approximately 40 mm high, so they had some more space for extra
components.
I hope it is now clear to you why you cannot expect this SCA adapter to
look like your other ones.
Regards,
Arie Bant. |
|
|
| Back to top |
|
|
Arie Bant
Guest
|
| Posted:
Mon Jul 04, 2005 6:20 am Post subject:
Re: NOT a lot different |
|
|
On 03/07/05 02:52, George Hester wrote:
| Quote: | Whatever all that means I can see you put some thought into it. I will keep
that for reference thanks.
|
My pleasure George.
My advice to you is, if you want to work with SCSI, you should try and
learn so much about it that at least you know what it is about at a
conceptual level and where you can find specific info if you need it.
Search Google for "SCSI Glossary".
For now, what did you not understand that makes you say "Whatever all
that means"?
Arie Bant.
| Quote: |
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:da2ahd$vug$1@news.freedom2surf.net...
On 30/06/05 23:40, George Hester wrote:
"Arie Bant" <abant@mail.com> wrote in message
news:d9vfbj$3bk$1@news.freedom2surf.net...
On 29/06/05 04:34, George Hester wrote:
Well thank you that was my intent all along. The ones you see at my
second
post are the ones I have. So I think you can understand why when I saw
what
I saw at eBay I was wondering why they didn't look like mine.
They look like that because passive termination has become obsolete and
no manufacturer I know of puts passive termination on anything these
days, because "narrow" 50-pin cabling is not compliant with LVD and
because the internal LED is generally rather useless compared to having
a LED on the front panel of the machine and it saves money not to put it
on.
Quite honestly I can only explain your "wondering" as a result of a lack
of understanding of SCSI. With respect, there is no rational
explanation why one should expect new SCA adapters to look like those
used before "ULTRA" SCSI was introduced.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9sua3$9dt$1@news.freedom2surf.net...
On 21/06/05 23:24, George Hester wrote:
Yes but will the ones I see at eBay work? That's my issue. They
don't
have
LEDs what else don't they have? The ability to work?
Depends on what you mean by "Work".
Just having had a second glance I noticed that some of the things you
described as connectors are not, they are Jumpers.
The adapters your URL pointed at are infact not so standard, but very
expensive.
There are two differences with the cheaper ones you pointed at in your
first posting:
1 These have built-in SCSI terminators, rather unusual and the large
number of jumpers looks to be there to enable/disable the terminators.
2 These are not LVD compatible, i.e only useful with old kit.
Did I say they are expensive? Shamefully so!
It seems your understanding of SCSI could do with reading some basic
information on how it works.
--
George Hester
_______________________________
"Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message
news:yXmte.338823$cg1.129226@bgtnsc04-news.ops.worldnet.att.net...
"George Hester" <hesterloli@hotmail.com> wrote in message
news:Msgte.26217$fp6.5436@twister.nyroc.rr.com...
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
That's the standard product. One with all those extra
headers/connectors
is
not anything usual.
With all due respect, "there is no rational explanation why one should
expect new SCA adapters to look like those used before "ULTRA" SCSI was
introduced," because that is what I have and they work. That seems
rational
to me not to you?
--
George Hester
_______________________________
Dear George,
I'll try again to explain in more detail.
The SCA adapter you have "looks" like it does because it has passive
terminators (the three yellow resistor SIL-packs) on board and some
jumpers to enable or disable these terminators and because it has a
"narrow" or 8-bit 50-pin connector. All that was fine in the days of 5
and 10 MHz SCSI bus speed and SCA-1. Since ULTRA SCSI and above
(Ultra2, Ultra3/160, Ultra320) the SCSI bus can operate at speeds in
excess of 20 MHz (40, 80, 160 Mhz).
At these speeds and for some other technical reasons, passive
termination does not work reliably if at all and in the case of a LVD
bus it simply does not work.
So it has become obsolete and I know of no manufacturer that still
incorporates passive termination on SCSI interfaces.
You state that you have Ultra SCSI working with these adapters. That is
very well possible. What you do not explain is what termination you
use. You could use an separate end-of-cable terminator of the active
sort or you could even use the build-in termination of some other
non-SCA SCSI device, active or not.
Perhaps you do not use active termination at all but passive
termination. Perhaps even the terminators on the SCA adapter. All that
is possible and may work, albeit that in the case of passive termination
the bus probably runs at a lower speed, i.e. 10 Mhz (=20 MB/sec), not at
20 MHz (=40 MB/sec).
Unless you do some measuring you would not neccesarily know the true bus
speed.
But in the right circumstances, only one device on the bus, a short
internal cable, you could be lucky and get away with it.
A matter of chance.
That is not what SCSI cabling now is designed for. In particular the $9
SCA adapters are explicitly advertised to be ULTRA320 compliant. That
means that passive termination is definitely useless because ULTRA320
uses Low Voltage Differential signals on the bus and that just does not
work with passive termination.
For the same reason there is no 50-pin connector on that adapter,
ULTRA320 is almost exclusively used on hard disk drives with a "Wide"
(=16 bit) interface and that excludes the 50-pin connectors.
You may also note that this adapter is lower than your older ones. That
is because it is made to fit behind a low profile 3.5" device,
aproximately 25 mm high.
The older ones were made to fit behind a "half height" drive,
approximately 40 mm high, so they had some more space for extra
components.
I hope it is now clear to you why you cannot expect this SCA adapter to
look like your other ones.
Regards,
Arie Bant.
|
|
|
| Back to top |
|
|
Arie Bant
Guest
|
| Posted:
Mon Jul 04, 2005 6:52 am Post subject:
Re: NOT a lot different |
|
|
On 04/07/05 02:20, Arie Bant wrote:
| Quote: | On 03/07/05 02:52, George Hester wrote:
Whatever all that means I can see you put some thought into it. I
will keep
that for reference thanks.
My pleasure George.
My advice to you is, if you want to work with SCSI, you should try and
learn so much about it that at least you know what it is about at a
conceptual level and where you can find specific info if you need it.
Search Google for "SCSI Glossary".
|
On second thought, this is your best bet:
http://www.paralan.com/gloswdlist.html
The others seem rather outdated and even plain wrong here and there.
There is a lot of mis-information about SCSI.
But it is the best, perhaps even only, universal standard bus for
computer peripherals we have at this moment.
If IBM had chosen the SCSI-bus for the PC, back in 82(PC-XT) or
84(PC-AT), as many commentators at the time thought they should have, we
would all be using it now, MoBos would all have a SCSI HBA, SCSI drives
would be as cheap as ATA drives now, ATA would not exist and the
ridiculous religious arguments about ATA-vs-SCSI would not take place.
| Quote: |
For now, what did you not understand that makes you say "Whatever all
that means"?
Arie Bant.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:da2ahd$vug$1@news.freedom2surf.net...
On 30/06/05 23:40, George Hester wrote:
"Arie Bant" <abant@mail.com> wrote in message
news:d9vfbj$3bk$1@news.freedom2surf.net...
On 29/06/05 04:34, George Hester wrote:
Well thank you that was my intent all along. The ones you see at my
second
post are the ones I have. So I think you can understand why when
I saw
what
I saw at eBay I was wondering why they didn't look like mine.
They look like that because passive termination has become obsolete
and
no manufacturer I know of puts passive termination on anything these
days, because "narrow" 50-pin cabling is not compliant with LVD and
because the internal LED is generally rather useless compared to
having
a LED on the front panel of the machine and it saves money not to
put it
on.
Quite honestly I can only explain your "wondering" as a result of a
lack
of understanding of SCSI. With respect, there is no rational
explanation why one should expect new SCA adapters to look like those
used before "ULTRA" SCSI was introduced.
--
George Hester
_______________________________
"Arie Bant" <abant@mail.com> wrote in message
news:d9sua3$9dt$1@news.freedom2surf.net...
On 21/06/05 23:24, George Hester wrote:
Yes but will the ones I see at eBay work? That's my issue. They
don't
have
LEDs what else don't they have? The ability to work?
Depends on what you mean by "Work".
Just having had a second glance I noticed that some of the things
you
described as connectors are not, they are Jumpers.
The adapters your URL pointed at are infact not so standard, but
very
expensive.
There are two differences with the cheaper ones you pointed at in
your
first posting:
1 These have built-in SCSI terminators, rather unusual and the
large
number of jumpers looks to be there to enable/disable the
terminators.
2 These are not LVD compatible, i.e only useful with old kit.
Did I say they are expensive? Shamefully so!
It seems your understanding of SCSI could do with reading some basic
information on how it works.
--
George Hester
_______________________________
"Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message
news:yXmte.338823$cg1.129226@bgtnsc04-news.ops.worldnet.att.net...
"George Hester" <hesterloli@hotmail.com> wrote in message
news:Msgte.26217$fp6.5436@twister.nyroc.rr.com...
Here this is very similar:
http://www.corpsys.com/store/prodinfo.asp?number=SCA2SCSIT&variation=&aitem=
25&mitem=34
That's the standard product. One with all those extra
headers/connectors
is
not anything usual.
With all due respect, "there is no rational explanation why one should
expect new SCA adapters to look like those used before "ULTRA" SCSI was
introduced," because that is what I have and they work. That seems
rational
to me not to you?
--
George Hester
_______________________________
Dear George,
I'll try again to explain in more detail.
The SCA adapter you have "looks" like it does because it has passive
terminators (the three yellow resistor SIL-packs) on board and some
jumpers to enable or disable these terminators and because it has a
"narrow" or 8-bit 50-pin connector. All that was fine in the days of 5
and 10 MHz SCSI bus speed and SCA-1. Since ULTRA SCSI and above
(Ultra2, Ultra3/160, Ultra320) the SCSI bus can operate at speeds in
excess of 20 MHz (40, 80, 160 Mhz).
At these speeds and for some other technical reasons, passive
termination does not work reliably if at all and in the case of a LVD
bus it simply does not work.
So it has become obsolete and I know of no manufacturer that still
incorporates passive termination on SCSI interfaces.
You state that you have Ultra SCSI working with these adapters. That is
very well possible. What you do not explain is what termination you
use. You could use an separate end-of-cable terminator of the active
sort or you could even use the build-in termination of some other
non-SCA SCSI device, active or not.
Perhaps you do not use active termination at all but passive
termination. Perhaps even the terminators on the SCA adapter. All that
is possible and may work, albeit that in the case of passive termination
the bus probably runs at a lower speed, i.e. 10 Mhz (=20 MB/sec), not at
20 MHz (=40 MB/sec).
Unless you do some measuring you would not neccesarily know the true bus
speed.
But in the right circumstances, only one device on the bus, a short
internal cable, you could be lucky and get away with it.
A matter of chance.
That is not what SCSI cabling now is designed for. In particular the $9
SCA adapters are explicitly advertised to be ULTRA320 compliant. That
means that passive termination is definitely useless because ULTRA320
uses Low Voltage Differential signals on the bus and that just does not
work with passive termination.
For the same reason there is no 50-pin connector on that adapter,
ULTRA320 is almost exclusively used on hard disk drives with a "Wide"
(=16 bit) interface and that excludes the 50-pin connectors.
You may also note that this adapter is lower than your older ones. That
is because it is made to fit behind a low profile 3.5" device,
aproximately 25 mm high.
The older ones were made to fit behind a "half height" drive,
approximately 40 mm high, so they had some more space for extra
components.
I hope it is now clear to you why you cannot expect this SCA adapter to
look like your other ones.
Regards,
Arie Bant.
|
|
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|
|
|
|
|
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