X3T9.2/90-039



March 1, 1990

Mr. Ronald Graczyk
CompuAdd Corporation
12303 Technology Blvd.
Austin, TX 78127

Subject: Response to BSR X3.131-198x (SCSI-2) Public Review Comment #6

Dear Mr. Graczyk,

Thank you for your interest in the SCSI-2 draft proposed standard.  The X3T9.2 
committee has reviewed your public review comment (X3T9.2/90-008) suggesting 
that a high-density ribbon contact connector be included in the standard.  The 
committee has devoted considerable attention to the connector issue.

You mention usage problems with some pin-and-receptacle connectors as the 
reason the "large" ribbon connectors were developed.  As you probably know, 
SCSI-1 included a miniature ribbon connector (0.085-inch contact centers) 
after problems with its original pin-and-socket connector became apparent.

The X3T9.2 committee certainly shared your concern when selecting the high-
density SCSI-2 connector.  The fact that they selected a tab-and-receptacle 
contact design in spite of the previous experience serves to demonstrate the 
robust design of these high-density connectors.  They have been in production 
for several years and are available from at least three vendors.  No usage 
problems have been reported to the committee.

Connector selection for I/O interface standards is always a difficult and 
time-consuming process.  X3T9.2 had many excellent connector proposals from 
which to select, including several that employed ribbon contacts.  After a 
successive elimination voting procedure, the current high-density connector 
was selected.  The final design was endorsed by a roll-call vote which 
passed 48 Yes, 7 No, 0 Abstain, and 13 Absent.

The committee has also consistently rejected the idea of including more than 
one high-density connector design in the SCSI-2 draft standard.  This would 
weaken the standard and create market confusion.  Accordingly, X3T9.2 has 
voted against adding a ribbon-contact connector to the SCSI-2 standard.

Please send a written statement to the X3 Secretariat (Attn: Lynn Barra) 
within fifteen working days saying whether you accept or reject this response.  
If you do not respond within fifteen working days, the Secretariat will assume 
that you have withdrawn the comment.

Sincerely Yours,


Del Shoemaker, X3T9 Chairman

cc: L. Barra, X3 Secretariat
    J. Lohmeyer, X3T9.2 Chairman
    J. Ryland, SPARC Liaison