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RAIL Revision Or Appendage Document  (ROAD)


ROAD ID#: 2.2
ISSUE TITLE:   Add an instance designator after an exclamation mark to the 
               syntax under [Topology].
REQUESTER:     Aaron Tang/John Keifer, Intel Corp.

DATE SUBMITTED: 3/11/96
DATE ACCEPTED BY RAIL WORKGROUP: 4/4/96 5/2/96

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STATEMENT OF THE ISSUE:

We have found it necessary to add a small feature to the node syntax under 
[Topology].  When a generic_name is used in the node column, if the netlist 
contains more than one connection to a certain component (ref_des) then the 
generic_name will be appended by an "instance designator".  This designator is 
appended immediately following the generic_name with an exclamation mark.  For 
example, generic_name!instance will be used.  In the attached file, "DRAM1!34" 
means pin thirty four of the component with generic_name "DRAM1".  Instance
designators can only be pin numbers (numeric or alphanumeric).

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STATEMENT OF THE RESOLVED SPECIFICATIONS:

Text to be added to the RAIL SPEC Usages Rule under [Topology]:

If a generic_name(node) contains more than one connection, then the 
generic_name will be appended by an "instance designator".  This designator
is appended immediately following the generic_name with an exclamation mark.
The instance designator can only be a pin number.  (e.g., "DRAM1!34" means
pin thirty four of the component with the generic_name of "DRAM1").  The pin
number can be either numeric or alphanumeric and must not exceed five 
charaters.  This allows the generic name with an instance designator to be up 
to 16 characters in length.

[Topology]                        RAS#(3:2)
Tpr                               PMC         R1           NA       NA      1 
R10                               R1          R2           10
Tmain                             R2          Tee1         NA       NA      7 
Tt1s2_a                           Tee1        DRAM2!34     2        NA      NA 
Tt1s2_b                           Tee1        DRAM2!44     2        NA      NA 
Tt1t2                             Tee1        Tee2         NA       NA      1 
Tt2s4_a                           Tee2        DRAM4!34     2        NA      NA 
Tt2s4_b                           Tee2        DRAM4!44     2        NA      NA


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ANALYSIS PATH/DATA THAT LED TO SPECIFICATION:

Without this new feature, it will be very ambiguous for the router 
to figure out the actual layout. For example, if the following topology
is intended:

          DRAM2 DRAM2  DRAM4  DRAM4
            X    X      X    X
             |   /       |   /
             |  /        |  /
             | /         | /
             |/          |/
  X----------X-----------X
  PMC       Tee1         Tee2

Without the instance designator feature, the syntax will be as follows:

Tpr                               PMC         Tee1         NA       NA      1 
Tt1s2                             Tee1        DRAM2        2        NA      NA 
Ts1s2                             Tee1        DRAM2        2        NA      NA 
Tt1t2                             Tee1        Tee2         NA       NA      1 
Tt2s4                             Tee2        DRAM4        2        NA      NA 
Ts2s4                             Tee2        DRAM4        2        NA      NA

However, the router may interpret DRAM2 in Ttls2 and Tsls2 as the 
same node and DRAM4 as well. This would cause the topology to be the following:

          DRAM2 DRAM2  DRAM4  DRAM4
            X----X      X----X
             |   /       |   /
             |  /        |  /
             | /         | /
             |/          |/
  X----------X-----------X
  PMC       Tee1         Tee2

With the instance designator feature, the following syntax will generate 
what is the intended topology:

Tpr                               PMC         Tee1         NA       NA      1 
Tt1s2_a                           Tee1        DRAM2!34     2        NA      NA 
Tt1s2_b                           Tee1        DRAM2!44     2        NA      NA 
Tt1t2                             Tee1        Tee2         NA       NA      1 
Tt2s4_a                           Tee2        DRAM4!34     2        NA      NA 
Tt2s4_b                           Tee2        DRAM4!44     2        NA      NA

      DRAM2!34 DRAM2!44 DRAM4!34  DRAM4!44
            X    X          X    X
             |   /           |   /
             |  /            |  /
             | /             | /
             |/              |/
  X----------X---------------X
  PMC       Tee1           Tee2


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