DOCUMENT:Q123324 17-DEC-2000 [win95x] TITLE :File Transfer Protocols Supported by HyperTerminal PRODUCT :Microsoft Windows 95.x Retail Product PROD/VER: OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows 95 ------------------------------------------------------------------------------- SUMMARY ======= This article contains a brief description of the file transfer protocols supported by HyperTerminal. MORE INFORMATION ================ Kermit ------ Kermit is a public domain protocol developed at Columbia University. It is a sliding-window protocol that supports batch file transfers and has a maximum block size of 94 bytes. It uses either half or full duplex. Kermit is unique because it supports either 7-bit or 8-bit data transmission, enabling PC to mainframe transfers. Kermit uses either CRC or Checksum error correction. Kermit transfers the filename, date, and size. X-Modem ------- X-Modem is a public domain 8-bit, error-checking communications protocol. It is a single file protocol, has a block size of 128 bytes, and transmits using half-duplex. The filename, date, and size are not transmitted by X-Modem. You must provide the name of the file being downloaded. X-Modem uses either CRC or Checksum error checking, with CRC being the default. X-Modem-1K ---------- X-Modem-1K is identical to X-Modem except that the block size is 1024 bytes. Y-Modem ------- The Y-Modem protocol is virtually the same as X-Modem, with one exception. Y-Modem uses 1024-byte blocks compared to the X-Modem 128-byte block. Because of its larger block size, Y-Modem is generally faster than X-Modem on a noise-free line. On noisy lines, X-Modem may be faster because when an error occurs, the block must be re-sent. Y-Modem must retransmit a 1024- byte block; with X-Modem's smaller blocks, less data has to be re-sent. Y-Modem-G --------- Y-Modem-G is a variant of the Y-Modem protocol. Y-Modem-G is a streaming protocol that sends 1024-byte blocks until instructed to stop. Y-Modem-G supports batch transfers. This protocol does not provide error correction or recovery. If an error is detected, the transfer is aborted. On a noise- free phone line using error-correcting modems, Y-Modem-G may be the fastest protocol. NOTE: Y-Modem-G does not provide error correction or recovery. It is designed specifically for high-speed error-correcting modems using V.42 or other hardware error correction. Z-Modem ------- The Z-Modem file transfer protocol provides reliable file transfers with complete end-to-end data integrity. Z-Modem uses 32-bit CRC error correction and a sliding-window block up to 1024 bytes in length. Z-Modem uses intelligent error recovery, which automatically decreases block size if the phone line deteriorates and attempts to increase block size as the phone line improves. Z-Modem also provides automatic downloads. When the host computer begins transferring using Z-Modem, the remote computer recognizes this and begins receiving the download automatically. Additional query words: upload zmodem ymodem ymodemg ymodem-g xmodem hyperterm ====================================================================== Keywords : Technology : kbWin95search kbZNotKeyword3 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2000.