File: rfc12.txt

package info (click to toggle)
doc-rfc 20181229-2
  • links: PTS, VCS
  • area: non-free
  • in suites: buster
  • size: 570,944 kB
  • sloc: xml: 285,646; sh: 107; python: 90; perl: 42; makefile: 14
file content (339 lines) | stat: -rw-r--r-- 9,221 bytes parent folder | download | duplicates (5)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339






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]