I am currently researching an article on high-speed comms and now I'm am
concentrating on FTP overheads.
It appears that FTP protocol overheads are:
YMODEM-g = 0.5% (due to 1K packet size (5/1024));
MobyTurbo90 = 1.1% (due to 1K subpacket size, 2 extra bytes for CRC-32
(2/1024) and escaping Ctrl-X (1/256));
Zmodem = 3.6% (as MobyTurbo90 + escaping 6 other network flow-control
chars (6/256)).
Are these overhead figures correct? I think I'm leaving somthing out
with Zmodem since I think Zmodem32's overhead should be 4%.
I've read Fosberg's ZMODEM.DOC but I'm still a bit unclear. The frame
size can be the same as a file's (assuming only one file transferred and
no FTP-level errors). The subpacket's size is typically 1K, although
going to 8K can produce a small (0.4)% improvement. What is the total
overhead for a 1K *data* subpacket  with 32-bit CRC i.e. how many
extra bytes are wrapped around a data subpacket?
Cheers, Dan Bridges, Brisbug PCUG.
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 X SLMR 2.1a X 
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