Data range used by UUCICO?

[Jim Deitch]

In article <1991Mar29.072005.7867 at hawkmoon.MN.ORG> det at hawkmoon.MN.ORG (Derek E. Terveer) writes:
>fenner at jazz.psu.edu (Bill Fenner) writes:
>
>>The UUCP g protocol requires an 8-bit datapath.  There exist other UUCP
>>protocols which do not require an 8-bit data path (i.e. the f protocol).
>
>Huh?  I thought that the f protocol merely assumed an error-free connection
>and said nothing about reducing the number of bit per byte, i.e., it is
>still 8-bit.
>
>derek

Here is the lines from fio.c :


/* $Header: fio.c,v 1.20 85/04/30 12:57:32 rick Exp $ */
/*	%M%	%I%	%E%	(Mathematisch Centrum)	*/

/*
 * flow control protocol.
 *
 * This protocol relies on flow control of the data stream.
 * It is meant for working over links that can (almost) be
 * guaranteed to be errorfree, specifically X.25/PAD links.
 * A sumcheck is carried out over a whole file only. If a
 * transport fails the receiver can request retransmission(s).
 * This protocol uses a 7-bit datapath only, so it can be
 * used on links that are not 8-bit transparent.
 *
 * When using this protocol with an X.25 PAD:
 * Although this protocol uses no control chars except CR,
 * control chars NULL and ^P are used before this protocol
 * is started; since ^P is the default char for accessing
 * PAD X.28 command mode, be sure to disable that access
 * (PAD par 1). Also make sure both flow control pars
 * (5 and 12) are set. The CR used in this proto is meant
 * to trigger packet transmission, hence par 3 should be 
 * set to 2; a good value for the Idle Timer (par 4) is 10.
 * All other pars should be set to 0.
 * Normally a calling site will take care of setting the
 * local PAD pars via an X.28 command and those of the remote
 * PAD via an X.29 command, unless the remote site has a
 * special channel assigned for this protocol with the proper
 * par settings.
 *
 * Author: Piet Beertema, CWI, Amsterdam, Sep 1984
 */

....A bunch of lines deleted....

/* Byte conversion:
 *
 *   from        pre       to
 * 000-037       172     100-137
 * 040-171               040-171
 * 172-177       173     072-077
 * 200-237       174     100-137
 * 240-371       175     040-171
 * 372-377       176     072-077
 */

...A bunch more deleted.....


So as you can see everything BEFORE 040 and after 171 is "quoted" by a
special character.  The reason the characters below 32 are changed is
because some X.25 pads will think they are control codes for it and
act on them, instead of just realizing they are a part of the data
stream.  The reason >171 is modified is because generaly X.25 is a 7
bit even parity environment.

Jim

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