Re: Rationale for aligning data on even bytes in a Unix shell file?

On 01.05.2025 01:49, Lew Pitcher wrote:

On Thu, 01 May 2025 00:15:12 +0200, Janis Papanagnou wrote:
 

On 30.04.2025 15:41, Scott Lurndal wrote:

Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:

On 30.04.2025 03:53, Lawrence D'Oliveiro wrote:

On Tue, 29 Apr 2025 11:17:50 +0300, Michael S wrote:
>

z/Os is alive and in good shape, but everybody knows that despite
the trademark it is not similar to Unix.

>
Just goes to show the worthlessness of the “Unix” name nowadays.

>
"UNIX" has a meaning that varied historically. But "Unix" is
commonly used as a name for the family of "UNIX-like" systems;
that's very useful since it allows to formulate commonalities
of this OS family.[*]
>
[*] As we've seen in the discussion of Unix file systems with
its basic structure of being built by sequences of octets[**]
and having two distinguished characters '\0' and '/'.
>
[**] BTW; does anyone know how e.g. the [historic] Borroughs

>
  s/Borroughs/Burroughs/
then
  s/Burroughs/Sperry/

>
Oh, sorry, I actually made even a more serious mistake beyond a typo;
>
   s/Borroughs/Honeywell 6000/
>
But the question was not so much about the concrete system label but
the principle question what happens if a system's character width is
defined as 9 bit, the underlying hardware (like hard disks) probably
8 bit,

 
A quick read through the Wikipedia article on the Honeywell 6000 and
another read through the documentation on the (related) DDS190 disk
storage unit (see https://www.manualslib.com/manual/1939073/Honeywell-6000-Series.html?page=8#manual)
indicates that the hard disks used 6-bit characters.

Thanks.

I haven't worked on a Honeywell 6000 myself (just found it listed
in an old book about Unix). I know that 6 bit characters where quite
common back these days (supported by 60 bit CDC 175 and 48 bit TR440,
for example).

I'm so used to common "contemporary" (late 1970's and later) discs
that it didn't occur to me that _hard disc_ hardware could be 6 bit
based.

That would mean
that, on disk, you could store a Honeywell 6000 36-bit word as 6 6bit
characters (or 2 9bit program characters in 3 6bit storage characters).

The book I was referring to mentions a 9 bit "C" 'char' type...

and a Unix OS file-system in between.

So the question remains how that's mapped onto the Unix file system
running on the Honeywell 6000 systems. If the OS is written in "C"
then I'd assume all characters would be 9 bit. The documentation for
the file system is non-specifically speaking about "bytes" - I assume
"9 bit bytes" - but I don't see other information about characters
in the directory. I'd assume it was all 9 bit oriented with the basic
convention of the characters '\0' and '/' as the only "limitation"
of the file system intact?

Janis