W8SDZ@SIMTEL20.ARPA (Keith Petersen) (05/09/85)
A new doc file detailing the YAM modem program protocols is now available from SIMTEL20: Filename Type Bytes CRC Directory MICRO:<CPM.YAM> YMODEM.DQC.1 BINARY 24704 4837H YAM uses the MODEM2/MODEM7 protocol for CRC and CHECKSUM and has it's own BATCH protocol. It also allows optionally setting the packet length to 1k instead of the usual 128-bytes, which should improve the throughput when using the new 2400-baud modems. Even if you have no interest in YAM, the portion detailing the MODEM procotol is useful. --Keith <W8SDZ@SIMTEL20.ARPA> UUCP: ...!decvax!brl-bmd!w8sdz or ...!unc!brl-bmd!w8sdz or ...!ihnp4!seismo!brl-tgr!w8sdz
CSTROM@SIMTEL20.ARPA (05/10/85)
I thought you might like to know the reason for the appearance of YMODEM.DOC at this point. Due to the new proliferation of 2400 baud modems, a lot of people are acutely aware of the shortcomings of Christensen protocol's use of 128 byte blocks. There has been a protracted discussion of this on Compuserve's CP/M interest group, and at present we expect that Ward Christensen will be authoring an article destined for Byte which will summarize his protocol as well as suggest an expansion. There is a good possibility that the extensions will be the YMODEM protocol as implemented in YAM, with or without some as yet unspecified additions. In fact, the father of YAM, Chuck Forsberg, may be a co-author. In the meantime, Irv Hoff is planning on making some modifications to MDM740 to support 1K blocks. Several of us have lobbied hard for him to follow the YAM format and I think that he has agreed at least in princpal. One of the strengths of Christensen protocol is its simplicity, and YAM expands upon it, adding functionality while not making the implementation unreasonably complex. In any case, my feeling is that Ward's article will define the protocol extensions and if Irv or anone else were to go off on another path, it would only muddy the waters and damage the universal strength of Christensen protocol. -Charlie