Synchronet v3.21e-Win32 (install) has been released (Mar-2026).

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ref:zmodem [2020/12/01 02:12] – [Data Subpacket] Added Data Subpacket Types "notes" column with important info digital manref:zmodem [2025/09/26 14:13] (current) – [ZMODEM Frame] Mention the Tera Term 0x8D 0x8A oddity digital man
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 ==== ZMODEM Frame ==== ==== ZMODEM Frame ====
-There 2 classes of ZMODEM Frames: +There are 2 classes of ZMODEM Frames: 
-  * Hexadecimal (HEX) frames, contain only US-ASCII characters +  - Hexadecimal (HEX) frames, containing only US-ASCII characters 
-  * Binary (BIN16 or BIN32) frames, contain //almost// all possible 8-bit octet values+  - Binary (BIN16 or BIN32) frames, containing //almost// all possible octet values
  
 === HEX Frame === === HEX Frame ===
   <frame header> [CR] LF [XON]   <frame header> [CR] LF [XON]
  
-HEX frames are terminated with an ASCII linefeed character. Some ZMODEM implementations send the HEX frame terminating linefeed character with the high bit set (0x8A). Also, for some HEX frame types, the frame terminator may be followed by an XON (0x11) character ("transmit on" in so-called "software flow control").+HEX frames are terminated with an ASCII linefeed character. A carriage-return (CR) character may precede the linefeed (LF) character. 
 + 
 +Some ZMODEM implementations send this terminating LF with the high bit set (0x8A, that's ASCII-LF with an even-parity bit set). Some ZMODEM implementations (e.g. Tera Term) inexplicably send **both** CR and LF characters with the parity bit set (i.e. 0x8D 0x8A). 
 + 
 +Also, for some HEX frame types, the frame terminator may be followed by an XON (0x11) character ("transmit on" in so-called "software flow control").
  
 === Binary Frame === === Binary Frame ===
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 ==== Frame Header ==== ==== Frame Header ====
-  <frame encoding> <frame type> <frame info> <crc>+  <frame encoding> <frame type> <frame info> <checksum> 
 + 
 +**Frame Encoding** (single byte): 
 + 
 +The //Frame Encoding// is also sometimes called the "Frame Style". 
 + 
 +^ Style  ^  AKA   ^ Value          ^ Frame Contents                       ^ Checksum   ^ 
 +| HEX    | ZHEX   | ASCII '''B'''  | Hexadecimal/US-ASCII characters only | 16-bit CRC | 
 +| BIN16  | ZBIN   | ASCII '''A'''  | Binary                               | 16-bit CRC | 
 +| BIN32  | ZBIN32 | ASCII '''C'''  | Binary                               | 32-bit CRC | 
 + 
 +Notes: 
 +  * All frames sent by the "receiver" must use HEX encoding. 
  
-**Frame Encoding** (single byte): HEX ('''B'''), BIN16 ('''A'''), or BIN32 ('''C''').\\ +**Frame Type** (single byte):
-All frames sent by the "receiver" must use HEX encoding.+
  
-**Frame Type** (single byte): ZDATA, ZRPOS, ZACK, ZEOF, etc.+^ Type     ^ Value ^ TX((from sender))^ RX((from receiver)) ^ Info    ^ Data Subpkt    ^ Notes ^ 
 +| ZRQINIT  | 0x00  |  Y               |  -                  | caps    | -              | Request ZRINIT from the receiver | 
 +| ZRINIT   | 0x01  |  -               |  Y                  | caps    | -              | Receiver Initialized | 
 +| ZSINIT   | 0x02  |  Y               |  -                  | flags   | Attn sequence  | Sender Initialized | 
 +| ZACK     | 0x03  |  Y               |  Y                  | offset  | -              | Positive Acknowledgment | 
 +| ZFILE    | 0x04  |  Y               |  -                  | options | File metadata  | File information (name/len/date) | 
 +| ZSKIP    | 0x05  |  -               |  Y                  |         | -              | Skip (don't send) this file | 
 +| ZNAK     | 0x06  |  Y               |  Y                  |         | -              | Negative Acknowledgment | 
 +| ZABORT   | 0x07  |  -               |  Y                  |         | -              | Terminate batch file transfer | 
 +| ZFIN     | 0x08  |  Y               |  -                  |         | -              | Terminate transfer session | 
 +| ZRPOS    | 0x09  |  -               |  Y                  | offset  | -              | Reposition the send offset | 
 +| ZDATA    | 0x0A  |  Y               |  -                  | offset  | File contents  | One or more data subpackets follow | 
 +| ZEOF     | 0x0B  |  Y               |  -                  | offset  | -              | End of file reached | 
 +| ZFERROR  | 0x0C  |  -               |  Y                  |         | -              | File I/O error | 
 +| ZCRC     | 0x0D  |  Y               |  Y                  | CRC-32  | -              | File CRC request/response | 
 +| ZFREECNT | 0x11  |  Y               |  -                  | f-space | -              | Request free disk space |
  
-**Frame Info**: Up to 15 bytes (but typically 4) of frame type-specific information. Note that later claims of //16// bytes of possible frame header data include the //Frame Type// byte.+**Frame Info**: Up to 15 bytes (but typically 4) of frame type-specific information.\\ 
 +Note that later claims of //16// bytes of possible frame header data include the //Frame Type// byte.
  
 **Frame Header Integrity**: The //Frame Type// and //Frame Info// are integrity-protected with either a 16-bit or 32-bit CRC (determined by the frame encoding). **Frame Header Integrity**: The //Frame Type// and //Frame Info// are integrity-protected with either a 16-bit or 32-bit CRC (determined by the frame encoding).
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 The pathname (conventionally, the file name) is sent as a The pathname (conventionally, the file name) is sent as a
 null terminated ASCII string.  null terminated ASCII string. 
-No spaces are included in the pathname. +No spaces are included in the pathname. ((some ZMODEM implementations support path/file names that include spaces))
  
 Filename Considerations Filename Considerations

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