svlug_some_scsi_minutia

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Date: Thu, 4 Jan 2001 18:05:28 -0800
To: svlug@svlug.org
Subject: Re: [svlug] SCSI cable needed
From: Rick Moen <rick@linuxmafia.com>

begin Mike O'Neill quotation:

> I have a 50-pin internal scsi connection that I need to take externally.

Not necessarily a good idea.  Fast20 single-ended SCSI becomes out of
spec if you exceed 1.5 meters total SCSI-chain length.  You may already
be pushing it.

> The external connector can be just about anything since I could use
> converters to get the final connector needed.  The problem is that I cannot
> find this anywhere.

You can look up the official names of the connectors commonly used for
SCSI external connectors -- but the problem is that the vendors will
just stare blankly at you, when you _use_ those names.  I therefore tend
to pull the catalogue off the counter and point, instead.

There are SCA connectors for hot-swap (_not_ what you want).  There are
DD-50P, Mini Micro (aka "High Density"), and DD-50SA connectors.  There
are so-called "Centronics" connectors (probably the most-common for the
SCSI-2 generation of parts).  There are so-called "wide-SCSI-3 P"
connectors (not what you want).  There are IBM "Burndy"
no-I'm-not-really-SCSI connectors.  There are thankfully long-gone 
Apple / Future Domain / Trantor DB-25S connectors <shudder>.  

Aren't you glad you asked?

You probably want "Centronics" SCSI hardware.

> Do you have any suggestions for where I should look?

In the comp.periphs.scsi FAQ:
http://www.landfield.com/faqs/scsi-faq/part1/

If local to Sunnyvale, you can probably find what you want at Action
Computers or Halted Specialties.
 
> For clarification, U160 (LVD 68 pin) connectors are _not_ backward
> compatable with say scsi 2 or 3, right?  Thanks.  -m

No and yes:  There are converters.

And the term "SCSI 3" probably doesn't mean what you think it does.  
See the FAQ, for the gruesome details.

===
Date: Thu, 4 Jan 2001 22:36:13 -0800
To: svlug@svlug.org
Subject: Re: [svlug] SCSI cable needed
From: Rick Moen <rick@linuxmafia.com>

begin  Mike O'Neill quotation:
 
> I know what your thinking.  Why in hell would he want to do that?  The thing
> is that I have an unused channel that could be put to use with a legacy
> device.  -m

Put said device inside the main system box case.  Add it to the internal
SCSI ribbon connector.  And you're done.

Unless you're talking about a flatbed scanner or such.

===
Date: Thu, 4 Jan 2001 18:05:28 -0800
To: svlug@svlug.org
Subject: Re: [svlug] SCSI cable needed
From: Rick Moen <rick@linuxmafia.com>

begin Mike O'Neill quotation:

> I have a 50-pin internal scsi connection that I need to take externally.

Not necessarily a good idea.  Fast20 single-ended SCSI becomes out of
spec if you exceed 1.5 meters total SCSI-chain length.  You may already
be pushing it.

> The external connector can be just about anything since I could use
> converters to get the final connector needed.  The problem is that I cannot
> find this anywhere.

You can look up the official names of the connectors commonly used for
SCSI external connectors -- but the problem is that the vendors will
just stare blankly at you, when you _use_ those names.  I therefore tend
to pull the catalogue off the counter and point, instead.

There are SCA connectors for hot-swap (_not_ what you want).  There are
DD-50P, Mini Micro (aka "High Density"), and DD-50SA connectors.  There
are so-called "Centronics" connectors (probably the most-common for the
SCSI-2 generation of parts).  There are so-called "wide-SCSI-3 P"
connectors (not what you want).  There are IBM "Burndy"
no-I'm-not-really-SCSI connectors.  There are thankfully long-gone 
Apple / Future Domain / Trantor DB-25S connectors <shudder>.  

Aren't you glad you asked?

You probably want "Centronics" SCSI hardware.

> Do you have any suggestions for where I should look?

In the comp.periphs.scsi FAQ:
http://www.landfield.com/faqs/scsi-faq/part1/

If local to Sunnyvale, you can probably find what you want at Action
Computers or Halted Specialties.
 
> For clarification, U160 (LVD 68 pin) connectors are _not_ backward
> compatable with say scsi 2 or 3, right?  Thanks.  -m

No and yes:  There are converters.

And the term "SCSI 3" probably doesn't mean what you think it does.  
See the FAQ, for the gruesome details.

===
Date: Thu, 4 Jan 2001 22:36:13 -0800
To: svlug@svlug.org
Subject: Re: [svlug] SCSI cable needed
From: Rick Moen <rick@linuxmafia.com>

begin  Mike O'Neill quotation:
 
> I know what your thinking.  Why in hell would he want to do that?  The thing
> is that I have an unused channel that could be put to use with a legacy
> device.  -m

Put said device inside the main system box case.  Add it to the internal
SCSI ribbon connector.  And you're done.

Unless you're talking about a flatbed scanner or such.

===

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