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From: davewh@microsoft.UUCP
Newsgroups: comp.sys.apple2
Subject: Re: Request for comment on Kermit
Message-ID: <9104291533.AA20302@beaver.cs.washington.edu>
Date: 28 Apr 91 11:55:30 GMT
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Organization: The Internet
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Unknown speculates:

>	There's gotta be some other reason for the speedup.

It's called overhead. For each packet of n bytes, there are 5 bytes
of overhead and then the waiting for the acknowledge. 1k of xmodem
packets works out to 8 ACK waits and 40 bytes of overhead. 1k of
ymodem packets works out to 1 ACK wait and 5 bytes of overhead. The
number of bytes of overhead don't start to become evident until
you've sent quite a number of packets (after 60k or something). The
real dead time is in the ACK waits. That's the theory as to why
Zmodem is faster than the various xmodem variants. the Zmodem sender
doesn't wait for ACKs, it just looks for NAKs. No NAK? Keep sending.

Now, 2 fast computers talking to each other don't suffer much on the
ACK waits. I noticed that putting an accelerator in your GS will
improve efficiency just a bit.

Dave Whitney	Microsoft Corp, Work Group Apps  dcw@goldilocks.lcs.mit.edu or
I wrote Z-Link and BinSCII - send me bug reports. {...}!uunet!microsoft!davewh
I only work here. All opinions herein aren't Bill's, they're mine.
"We're samplin' - Yeah we're doin' it. We take good music an' we ruin it."
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