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ref:ymodem [2011/07/13 21:31] – digitalmanref:ymodem [2011/07/13 21:46] – digitalman
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 Jeff Garbers (Crosstalk package development director) said it all: "With Jeff Garbers (Crosstalk package development director) said it all: "With
 protocols in the public domain, anyone who wants to dink around with them protocols in the public domain, anyone who wants to dink around with them
-can go ahead." [1]+can go ahead." ((Page C/12, PC-WEEK July 12, 1987))
  
 Documents containing altered examples derived from YMODEM.DOC have added Documents containing altered examples derived from YMODEM.DOC have added
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 receiver commands CRC-16. receiver commands CRC-16.
  
-              Figure 1.  XMODEM-1k Blocks+=== Figure 1: XMODEM-1k Blocks ===
  
               SENDER                                  RECEIVER               SENDER                                  RECEIVER
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                                                       ACK                                                       ACK
  
-              Figure 2.  Mixed 1024 and 128 byte Blocks+=== Figure 3: Mixed 1024 and 128 byte Blocks ===
  
               SENDER                                  RECEIVER               SENDER                                  RECEIVER
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 RZSZ.ZOO should answer other questions about YMODEM batch protocol. RZSZ.ZOO should answer other questions about YMODEM batch protocol.
  
-              Figure 3.  YMODEM Batch Transmission Session+=== Figure 3: YMODEM Batch Transmission Session ===
  
               SENDER                                  RECEIVER               SENDER                                  RECEIVER
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                                                       ACK                                                       ACK
  
-            Figure 4.  YMODEM Batch Transmission Session-1k Blocks+=== Figure 4: YMODEM Batch Transmission Session-1k Blocks ===
  
             SENDER                                  RECEIVER             SENDER                                  RECEIVER
Line 585: Line 585:
  
  
-           Figure 5.  YMODEM Filename block transmitted by sz +=== Figure 5: YMODEM Filename block transmitted by sz === 
 +<code>
            -rw-r--r--  6347 Jun 17 1984 20:34 bbcsched.txt            -rw-r--r--  6347 Jun 17 1984 20:34 bbcsched.txt
  
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            70 00000000 00000000 00000000 00000000            70 00000000 00000000 00000000 00000000
            80 000000CA 56            80 000000CA 56
- +</code> 
-                Figure 6.  YMODEM Header Information and Features+=== Figure 6: YMODEM Header Information and Features ====
  
     _____________________________________________________________     _____________________________________________________________
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 recovery. recovery.
  
-            Figure 7.  YMODEM-g Transmission Session+=== Figure 7: YMODEM-g Transmission Session ====
  
             SENDER                                  RECEIVER             SENDER                                  RECEIVER
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   <nak> 15H   <nak> 15H
   <can> 18H   <can> 18H
-   +  <C>   43H
----- +
-<C>   43H+
  
  
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   * The last block sent is no different from others, i.e.  there is no "short block".   * The last block sent is no different from others, i.e.  there is no "short block".
    
-                  Figure 8.  XMODEM Message Block Level Protocol+=== Figure 8: XMODEM Message Block Level Protocol ===
  
     Each block of the transfer looks like:     Each block of the transfer looks like:
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 getting garbaged.  <xx> represents the checksum byte. getting garbaged.  <xx> represents the checksum byte.
  
-                  Figure 9.  Data flow including Error Recovery+=== Figure 9: Data flow including Error Recovery ===
  
     SENDER                                  RECEIVER     SENDER                                  RECEIVER
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 protocol. A description of this handshake is presented in section 10. protocol. A description of this handshake is presented in section 10.
  
-                Figure 10.  Message Block Level Protocol, CRC mode+=== Figure 10: Message Block Level Protocol, CRC mode ===
  
     Each block of the transfer in CRC mode looks like:     Each block of the transfer in CRC mode looks like:
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 block is the coefficient of X^0 in the message polynomial. block is the coefficient of X^0 in the message polynomial.
  
-               Figure 11.  Example of CRC Calculation written in C+===Figure 11: Example of CRC Calculation written in C ===
  
     The following XMODEM crc routine is taken from "rbsb.c".  Please refer to     The following XMODEM crc routine is taken from "rbsb.c".  Please refer to
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 represents the checksum byte. represents the checksum byte.
  
-          Figure 12.  Data Flow: Receiver has CRC Option, Sender Doesn't+=== Figure 12: Data Flow: Receiver has CRC Option, Sender Doesn't ===
  
     SENDER                                        RECEIVER     SENDER                                        RECEIVER
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 2 CRC bytes. 2 CRC bytes.
  
-               Figure 13.  Receiver and Sender Both have CRC Option+=== Figure 13: Receiver and Sender Both have CRC Option ===
  
     SENDER                                       RECEIVER     SENDER                                       RECEIVER
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 implement XMODEM, YMODEM, and ZMODEM with state of the art features and implement XMODEM, YMODEM, and ZMODEM with state of the art features and
 reliability. reliability.
- 
- 
-                                 LIST OF FIGURES 
- 
- 
-     Figure 1.  XMODEM-1k Blocks..........................................  11 
- 
-     Figure 2.  Mixed 1024 and 128 byte Blocks............................  11 
- 
-     Figure 3.  YMODEM Batch Transmission Session.........................  15 
- 
-     Figure 4.  YMODEM Batch Transmission Session-1k Blocks...............  15 
- 
-     Figure 5.  YMODEM Filename block transmitted by sz...................  16 
- 
-     Figure 6.  YMODEM Header Information and Features....................  16 
- 
-     Figure 7.  YMODEM-g Transmission Session.............................  17 
- 
-     Figure 8.  XMODEM Message Block Level Protocol.......................  19 
- 
-     Figure 9.  Data flow including Error Recovery........................  20 
- 
-    Figure 10.  Message Block Level Protocol, CRC mode....................  22 
- 
-    Figure 11.  Example of CRC Calculation written in C...................  23 
- 
-    Figure 12.  Data Flow: Receiver has CRC Option, Sender Doesn't........  25 
- 
-    Figure 13.  Receiver and Sender Both have CRC Option..................  26 
- 
  
 ===== See Also ===== ===== See Also =====

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