Re: USB-serial adapter suggestions needed

From: Mark Millard <marklmi_at_yahoo.com>
Date: Wed, 27 Dec 2023 16:57:42 UTC
On Dec 27, 2023, at 05:48, John F Carr <jfc@mit.edu> wrote:
> 
>> On Dec 27, 2023, at 03:30, Mark Millard <marklmi@yahoo.com> wrote:
>> 
>> 0000: 6C 6F 67 69 6E 3A 20 C3 AF C2 BF C2 BD C3 AF C2  login: .........
>> 0010: BF C2 BD C3 AF C2 BF C2 BD C3 AF C2 BF C2 BD C3  ................
>> 0020: AF C2 BF C2 BD C3 AF C2 BF C2 BD C3 AF C2 BF C2  ................
>> 0030: BD C3 AF C2 BF C2 BD 0A 50 61 73 73 77 6F 72 64  ........Password
>> 0040: 3A                                               :
>> 
>> The byte pairs that start with C3 's and C2's look far from
>> random to me --also they do not look like glitches.
> 
> Those byte pairs are valid UTF-8.

But not unique to a UTF-8 encoding: not self identifying.
Extended ASCII is another possibility, for example.

> C3 AF = 000 1110 1111 = EF
> C2 BF = 000 1011 1111 = BF
> C2 BD = 000 1011 1101 = BD
> 
> What EF BF BD means, I can't say.  As Unicode it is "�".
> Maybe UTF-8 encoded 8 bit line noise.

The subsequence (line split differently):

C3 AF C2 BF C2 BD
C3 AF C2 BF C2 BD
C3 AF C2 BF C2 BD
C3 AF C2 BF C2 BD
C3 AF C2 BF C2 BD
C3 AF C2 BF C2 BD
C3 AF C2 BF C2 BD
C3 AF C2 BF C2 BD

(8 repititions) is rather systematic for a glitch
or random line noise.

As UTF-8 (also showing UTF-16's alternate, matching John's)
( https://www.charset.org/utf-8 ):

C3 AF: 239 U+00EF C3 AF ï Latin Small Letter I With Diaeresis
C2 BF: 191 U+00BF C2 BF ¿ Inverted Question Mark
C2 BD: 189 U+00BD C2 BD ½ Vulgar Fraction One Half

As extended ASCII ( https://www.ascii-code.com/ ):

C3: 195 303 C3 11000011 Ã &#195; &Atilde; Latin capital letter A with tilde
C2: 194 302 C2 11000010 Â &#194; &Acirc; Latin capital letter A with circumflex
BF: 191 277 BF 10111111 ¿ &#191; &iquest; Inverted question mark
BD: 189 275 BD 10111101 ½ &#189; &frac12; Fraction one half
AF: 175 257 AF 10101111 ¯ &#175; &macr; Spacing macron - overline
Binary is      ^^^^^^^^

So C3 AF C2 BF C2 BD on separate lines with binary showing are:

C3: 11000011
AF: 10101111
C2: 11000010
BF: 10111111
C2: 11000010
BD: 10111101
C3: 11000011

So: multi-bit changes from one to the next across the
repeating sequence.

Again: It does not appear to me to be gitches or random
line noise. Systematic line noise also seems rather
unlikely.

===
Mark Millard
marklmi at yahoo.com