Xref: utzoo comp.binaries.ibm.pc.d:1661 comp.sys.ibm.pc:22696
Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!unmvax!pprg.unm.edu!hc!ames!pasteur!helios.ee.lbl.gov!nosc!humu!uhccux!julian
From: julian@uhccux.uhcc.hawaii.edu (Julian Cowley)
Newsgroups: comp.binaries.ibm.pc.d,comp.sys.ibm.pc
Subject: Re: DSZ rz & sz
Message-ID: <2919@uhccux.uhcc.hawaii.edu>
Date: 3 Jan 89 06:55:43 GMT
References: <54@VAX1.CC.UAKRON.EDU>
Distribution: na
Organization: University of Hawaii at Manoa
Lines: 30

In article <54@VAX1.CC.UAKRON.EDU> Gregg Thompson writes:
>	Now how does one get rz and sz on Unixand dsz sz & rz to work at
>1024 blocks??  On bulliten boards I can upload and download at 1024 blocks
>just using standard commands with dsz (dsz rz and dsz sz), but when it comes
>to the Unix system it doesn't send or receive at 1024 characters a block!?!?!
>Ideas???

Actually, the block size you are referring to is known as the
subpacket size, because the subpacket may or may not elicit a
response from the receiver, unlike an X/Ymodem block which always
elicits a response.  The subpacket size itself is determined
solely by the sender, however, and is usually based on the line
speed.  According to the Zmodem documentation, which the sz and
rz programs follow, the recommended sizes for optimum throughput
are 256 bytes for below 2400 baud, 512 for 2400 baud, and
1024 for 4800 baud and above.  In my experience, like yours,
most bulletin boards send 1024 bytes at 1200 baud, and there is
no way to set it otherwise in case you have a bad connection.
The reason for this is that the particular implementors of the
remote Zmodem made the interface overly simple (perhaps
necessarily), so that people wouldn't be overwhelmed by the many
features that Zmodem actually supports.

Sorry for the technical response, but it is interesting to note
that Zmodem can be more flexible than it seems at first glance.

julian@uhccux.uhcc.hawaii.edu
uunet!ucsd!nosc!uhccux!julian
julian@uhccux.bitnet
"People who aren't amused don't talk."