[Docs] [txt|pdf]



This is a modified version of the Internet RFC suitable for machine-translating. Original version is available here: RFC12




Network Working Group                                       M. Wingfield
Request for Comments: 12  REVISED                         26 August 1969


                    
IMP-HOST INTERFACE FLOW DIAGRAMS

The following flow diagrams were extracted from the logic diagrams provided in Appendix B of BBN Report No. 1822. These diagrams indicate the logical sequence of hardware operations which occur within the IMP-HOST interface. The logic names appearing in the blocks correspond to the logic elements found in Appendix B.
Wingfield                                                       [Page 1]


RFC 12              IMP-HOST INTERFACE FLOW DIAGRAMS      26 August 1969
IMP to HOST Message
                       +----------+
                       |  Start   |
                       |  Input   |
                       +----------+
                             |
                             V
                 +------------------------+
                 | LAST <--0; IMPERR <--0 |
                 | PAD <--0; IN REQST <--0|
                 |  COUNTER <--0          |
                 +------------------------+      +---+
                             |<----------------- | B |
                             V                   +---+
                      +--------------+
                      | RFNIB <-- 1  |
                      +--------------+
                             |<--------------+
                             V               |
/ \ |
/ \ |
                        / THERE'S \ N        |
                        \YOUR BIT /----------+
                          \=1 ? /
                            \ /
                             |
        +------------------->V
        |                   / \
   +----+------+    N     /     \
   | IMP ERROR |<------ /   IMP   \
   | <--- 1    |        \  READY  /
   +-----------+          \ ?   /
                            \ /
| Y V
/ \
                          /     \
   +-----------+   Y    /  LAST   \
   | PAD <-- 1 |<-------\ IMP BIT /
   +-----------+          \ =1? /
        |                   \ /                 +---+
        +------------------->|<-----------------| C |
                             V                  +---+
                +-----------------------+
                |    PULSE SHIFT REG.   |       +---+
                |   INCREMENT COUNTER   |------>| A |
                |      RFNTR <-- 0      |       +---+
                +-----------------------+
Wingfield                                                       [Page 2]


RFC 12              IMP-HOST INTERFACE FLOW DIAGRAMS      26 August 1969
      +---+                +---+
      | C |                | A |
      +-+-+                +-+-+
        ^                    |
| Y V
       / \                  / \
     /     \          N   /WORD \
   /  PAD=1  \ <--------/ LENGTH  \
   \    ?    /          \   =1    /
     \     /              \  ?  /
       \ /                  \ /
        | N                  |
        V                    V
      +---+       +----------------------+
      | B |       |     INREQST <--1     |
      +---+       +----------------------+
                             |<-----------+
                             V            |
/ \ |
                          /DATA \         |
                        /HAS BEEN \_N_____|
                        \ TAKEN   /
\ ? /
\ /
                             V Y
                  +----------------------+
                  |    INREQST <--0      |
                  +----------------------+
                             V
                            / \
                          /     \              +------------+
                        / LAST = 1\----------->|   END  OF  |
                        \    ?    /            |   MESSAGE  |
                          \     /              +------------+
                            \ /                       ^
                             | N                      |
                             V                        |
/ \ |
                          /     \                     |
                        / PAD = 1 \-------------------+
                        \     ?   /
\ /
\ /
| N
                             V
   +---+          +---------------------+
   | B |<---------|    CLEAR COUNTER    |
   +---+          +---------------------+
Wingfield                                                       [Page 3]


RFC 12              IMP-HOST INTERFACE FLOW DIAGRAMS      26 August 1969
HOST TO IMP MESSAGE
            +--------------+
            | START OUTPUT |
            +------+-------+
                   V
       +------------------------+
       | COUNTER <-- 1          |
       | LSTWD <--0; BTAVL <--0 |
       +-----------+------------+        +---+
                   |<--------------------| C |
                   V                     +---+
       +-----------+------------+
       |    OUT REQST <-- 1     |
       |     CLEAR SHIFT REG.   |
       +-----------+------------+
     +------------>|
     |             V
| / \
     |      N   /     \
     |_______ / STROBE  \
              \DATA WORD/
\ =1 ?/
\ /
                   V  Y
      +------------+------------+
      |  LOAD SHIFT  REGISTER   |
      |  OUTREQST <-- 0         |
      |  COUNTER  <-- 1         |
      +-------------------------+
      +---------->|
      |           V
      |          / \
      |        /     \
      |N     / RFNBIT  \
      +----- \   = 1   /
               \   ? /            +----------+
                 \ /              |          | N
                  V   Y           |         / \
         +--------+--------+      V       /     \
         |  THERE'S YOUR   |----------->/ RFNBIT  \
         | HOST BET <-- 1  |            \  = 0    /
         +-----------------+              \  ?  /
                                            \ /
                                             | Y
                                           +-+-+
                                           | A |
                                           +---+
Wingfield                                                       [Page 4]


RFC 12              IMP-HOST INTERFACE FLOW DIAGRAMS      26 August 1969
                               +---+
                               | A |
                               +---+
                                 V
                  +--------------+-------------+
                  | THERE'S YOUR HOST BIT <--0 |
                  |      BTAVL <-- 0           |
                  +----------------------------+
                                 V
/ \ / \
                              / WORD\   Y           /     \   Y
                            /LENGTH -1\---------->/  LSTWD  \---+
                            \   = 1   /           \   = 1   /   |
\ ? / \ ? / |
                                \ /                   \ /       |
                                 | N                   | N      |
                                 V                     |        |
                                / \                    |        |
                              / WORD\                  |        V
           ________________ / LENGTH  \                |  +------------+
           |                \  = 1    /                |  | LIBIT <- 1 |
           |                  \  ?  /                  |  +------------+
           |                    \ /                    V        |
           |                     |<-----------------------<------+
           |                     V
           |            +-----------------+
           |            | PUSH SHIFT REG. |
    +-------------+     |INCREMENT COUNTER|
    | LIBIT <-- 0 |     +-----------------+
    +-------------+              V
           |                   +---+
           |                   | B |
           V                   +---+
          / \
        /     \
      /  LSTWD  \ Y                          +-------------+
      \   = 1   /--------------------------->|   END OF    |
        \  ?  /                              |   MESSAGE   |
          \ /                                +-------------+
           | N
           V
         +---+
         | C |
         +---+


[ This RFC was put into machine readable form for entry ]
[ into the online RFC archives by Lorrie Shiota]
Wingfield                                                       [Page 5]


RFC 12              IMP-HOST INTERFACE FLOW DIAGRAMS      26 August 1969
Wingfield [Page 6]


    Html markup produced by rfcmarkup 1.124, available from
https://tools.ietf.org/tools/rfcmarkup/



Translate documents to 日本語, svenska, Nederlands, Deutsch, français, русский, italiano, español, Tiếng Việt, polski, português, 中文, українська, català, norsk, فارسی, suomi, Bahasa Indonesia, العربية, čeština, 한국어, Bahasa Melayu, magyar, română, српски and other languages.
inserted by FC2 system