are there some special about '\x1a' symbol

Grant Edwards grante at
Wed Jan 14 14:37:37 CET 2009

On 2009-01-14, Steve Holden <steve at> wrote:
> Unknown wrote:
>> On 2009-01-12, John Machin <sjmachin at> wrote:
>>> I didn't think your question was stupid. Stupid was (a) CP/M recording
>>> file size as number of 128-byte sectors, forcing the use of an in-band
>>> EOF marker for text files (b) MS continuing to regard Ctrl-Z as an EOF
>>> decades after people stopped writing Ctrl-Z at the end of text files.
>> I believe that "feature" was inherited by CP/M from DEC OSes
>> (RSX-11 or RSTS-11). AFAICT, all of CP/M's file I/O API
>> (including the FCB) was lifted almost directly from DEC's
>> PDP-11 stuff, which probably copied it from PDP-8 stuff.
>> Perhaps in the early 60's somebody at DEC had a reason.  The
>> really interesting thing is that we're still suffering because
>> of it 40+ years later.
> I suspect this is probably a leftover from some paper tape data formats,
> when it was easier to detect the end of a file with a sentinel byte than
> it was to detect run-off as end of file. It could easily date back to
> the PDP-8.

You're probably right.  That's why the "delete" character is
all 1's (all holes).  It's easy to punch more holes --
un-punching them is pretty arduous.


More information about the Python-list mailing list