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From: H. Peter Anvin on 20 Nov 2007 19:56 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 21 Nov 2007 07:38 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. -- Microsoft voice recognition live demonstration
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