From: H. Peter Anvin on
Wolfgang Kern wrote:
>
> Yes, both defininitions for ascii-control and unicode are conform
> and specifiy char(03h) as EOT 'end of text',
> while ctrl-A (01h) is SOH 'start of header'.
> I've seen many variants of text end-marks starting with a single
> 00h until a bit7-set literally "EOT/EOF" (c5,d0,d4/c6).
> M$-formats may have changed too often, so my latest text-editor
> seem to use just the file size to tell the end.
>

The current "best practice" seems to be:

- Treat 0x1A as EOF in text file;
- Don't generate 0x1A.

I have, however, seen a lot of programs, even back 15 years ago, that
would simply display 0x1A as a character, which indicates to me that the
use of 0x1A was waning already then.

-hpa
From: Phil Carmody on
Terence <tbwright(a)cantv.net> writes:
> On Nov 20, 12:45 pm, Phil Carmody <thefatphil_demun...(a)yahoo.co.uk>
> wrote:
>
> > Ctrl-Z in the ASCII standard in use when CP/M and DOS
> > were being designed is the SUB (substitute) character,
> > used to indicate that the character was read/received
> > with some kind of error (e.g. parity error), and this
> > is a placeholder. There were plenty of "end of <blah>"
> > characters in ASCII, but 26 wasn't one of them.
>
> Ctrl-Z is in fact the correct code to indicate end-of-text from the
> keyboard.

If the keyboard controller on the PC receives an 0x1A, then
it will presume that the keyboard is sending it something to
do with the '[' key, if I remember my scan codes.

> It still works in current MS operating systems and is hunted for in
> the processing of input from the keyboard when using service calls for
> keyboard input.
>
> NAK is also #1a in asynchronous RS232C protocol, and #11 is ACK.

Got a source for that? A quick web search indicates that the
ASCII #15 is the NAK in RS232 contexts.

Are you abandoning the "ASCII" argument now, and trying to
justify the meaning of ^Z to CP/M and DOS in terms of NAKs,
which are sent by clients to data sources in order to request
resends of failed data, and RS232 instead now?

Phil
--
Dear aunt, let's set so double the killer delete select all.
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