DB>It appears that FTP protocol overheads are:
DB>YMODEM-g = 0.5% (due to 1K packet size (5/1024));
DB>MobyTurbo90 = 1.1% (due to 1K subpacket size, 2 extra bytes for CRC-32
DB>(2/1024) and escaping Ctrl-X (1/256));
DB>Zmodem = 3.6% (as MobyTurbo90 + escaping 6 other network flow-control
DB>chars (6/256)).
DB>Are these overhead figures correct? I think I'm leaving somthing out
DB>with Zmodem since I think Zmodem32's overhead should be 4%.
Not being a programmer I understand what you are asking for but am not
at a level where I can answer adequately however; my trying to translate
the contents of dsz.doc since the late eighties has provided some
knowledge on the subject.
X Y & Zmodem are in the public domain but above most appear that you are
talking about the protocols when driven by DSZ (copyright Omen
Technology Inc.).
DSZ (.com and .exe) enhance throughput and allow (registered) users to
change any of those protocol parameters which are adjustable or only a
few parms for unregistered copies.
DB>I've read Fosberg's ZMODEM.DOC but I'm still a bit unclear. The frame
DB>size can be the same as a file's (assuming only one file transferred and
DB>no FTP-level errors). The subpacket's size is typically 1K, although
DB>going to 8K can produce a small (0.4)% improvement.
Unclear ? You and about 99.5% of the rest of the planet, I guess that's
just the way Chuck is.
I believe he (now) recommends that the pB parameter for dsz.com not
exceed 4096 bytes (formerly 8192) and not be changed from the default
unless absolutely necessary whereas the limit for dsz.exe remains at
16384 bytes.
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