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VRf-Sequencing_Pins

Question asked by VRFuser on Aug 6, 1997
send q VRf-Sequencing_Pins ww JOEL_DUNSMORE@HP-Sonoma-om1.om.hp.com vrf

from: Greg Goebel / HP-MXD
      gvg@lvld.hp.com / 970-679-3030 / FAX 970-679-5971
      website:  ftp://fcext3.external.hp.com/dist/mxd/index.html
to:   VRf-Joel Dunsmore
date: Wednesday, 06 August 1997 1524 MDT

Joel:

As a rule I would use sequence-out pins, but I've never analyzed the issue
in such detail as to give a definitive answer.

We did have a very odd problem with the Japanese reporting that a program
worked faster on VEE 3.0 than it did on VEE 4.0.  Turned out their Timer
was triggered off the data output, not the sequence-out pin, and since there
were a number of different objects snaked off the data output pin the
execution order varied, changing the time.

We wired it to the sequencing pins and it worked fine.

I noticed the paths to my address from you are quite convoluted -- see below.
I think this may have something to do with the FUBAR on Susan Manson's eval
feedback.  Could you send a TEST-PLEASE DISREGARD message to the VRf so I
can inspect your paths for a possible clue?

[%%] regards -- gvg


--------------------------------- cut here ----------------------------------
>From: JOEL_DUNSMORE@HP-Sonoma-om1.om.hp.com
Date: Wed, 6 Aug 97 14:13:23 -0700
Subject: Re: VRf-Junctions in Vee4, FIFO?

Item Subject: VRf-Junctions in Vee4, FIFO?
     Greg,
        Thanks for the reply.
    
     I was able to get everything working by using the Sequence out of the
     upper device to sequence the next lower device, just as in your
     picture.
    
     What I had tried originally is using the DATA output of the upper
     device to trigger the sequence of the next lower device:
    
    
     ----                    -----
       1 |___________________| Juntion
     ----   |
            |
       -----|
       |
     -----
       2  |------------------
     -----
    
     I thought it was a "good thing" to use data propogation to control the
     sequence flow, and I did watch the "bouncing ball" to see that the
     data inputs to the junctions did occur in the proper order.  I guess I
     was lucky in the Vee 3 in that the order I hooked up the wires was the
     order I wanted the data, but I am surprised that the data flow doing
     the sequencing doesn't work. 
    
     Is there a better, intuitive way to know if or when to use data to
     sequence items, or do you always want to use sequence out pins.
    
     Thanks, Joel


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