A problem in SPI

Steve Finch TFINCHS%A1.VAX2T.mrouter at vax2t.tus.ssi1.com
Fri Feb 25 07:44:23 PST 1994

I have noticed a minor problem.  Was it the intent to change the timing of 
a Selection or Reselection after negotiating for Fast Synchronous 

The Selection and Reselection services specify System Deskew Delay as part 
of their descritpions.  This value, according to Table 10, changes between 
Fast and Slow/Asynch timing.  Since we power up async we would utilize one 
timing, and once we negotiated for Fast transfers, we could use another 

I don't think the system skew changes just because to devices have agreed 
to run fast.

I also noted that there are references to "deskew delays" which are not 
defined.  I assumed that these were "system deskew delays" (as an example, 
see 10.3.4, in paragraph beginning "When the initiator...").

This led me to review all of the differences between Fast and Slow timings 
in Table 10.  Can anyone explain why the Transmit Hold Time changes between 
Fast and Slow, but the Receive Hold Time doesn't?  Or why the Transmit Hold 
Time varies between the two modes, but the Transmit Setup Time doesn't?

Steve Finch
Silicon Systems
Ph:  714 573-6808
Fx:  714 573-6916
email:  5723283 at mcimail.com

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