Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!rutgers!sunybcs!boulder!hao!oddjob!gargoyle!ihnp4!homxb!mtuxo!mtune!codas!killer!usl!usl-pc!jpdres10
From: jpdres10@usl-pc.UUCP (Green Eric Lee)
Newsgroups: comp.dcom.modems
Subject: Re: 8-bit byte can be sent w/o xform ?
Message-ID: <91@usl-pc.UUCP>
Date: Wed, 14-Oct-87 13:46:03 EDT
Article-I.D.: usl-pc.91
Posted: Wed Oct 14 13:46:03 1987
Date-Received: Sat, 17-Oct-87 10:09:56 EDT
References: <167100015@uiucdcsb>
Organization: Univ. of Southwestern La., Lafayette
Lines: 29

Distribution:

Keywords:

Summary:

Expires:

Sender:

Reply-To:

Followup-To:


In message <167100015@uiucdcsb>, kkim@uiucdcsb.cs.uiuc.edu says:
>   it seems that one 7-bit ascii character is sent as one unit.
>however, binary files which uses all 8 bits are usually transformed
>before being sent - that is, 3 8-bit bytes are transformed to 4 6-bit 
>units, slightly modified (adding some number to make it non-control
>character), and then sent as 4 units, not 3.

1200 baud modems have no inherent problem with sending 8-bit data.
Modems do not understand parity. They just send what they get, and
leave the interpretation up to the reciever. I do 8-bit transfers all
the time, with both Unix and various microcomputers.  If what you
describe is actually happening, it is probably a "feature" of your
computer and/or software. For example, many terminal servers are
incapable of handling 8-bit characters, and at many installations, the
dial-up modems are connected to the same terminal servers as those in
the terminal rooms. Flow control is an especial culprit in the
inability to handle binary data. In an attempt to get around these
problems, the Kermit file transfer protocol was created. It does
quoting of control codes, and, optionally, quoting of 8th-bit-set
characters. This quoting mechanism in no way resembles the one you
mention (i.e. breaking 3 8-bit bytes into 4 6-bit bytes), and I am at
a loss to figure out exactly what the heck is actually going on in
your case. Maybe more details about your installation, software, etc.
would be advisable.

--
Eric Green  elg@usl.CSNET       from BEYOND nowhere:
{ihnp4,cbosgd}!killer!elg,      P.O. Box 92191, Lafayette, LA 70509
{ut-sally,killer}!usl!elg     "there's someone in my head, but it's not me..."